RESUMO
BACKGROUND: Doxorubicin is an important anticancer drug, however, elicits dose-dependently cardiomyopathy. Given its mode of action, i.e. topoisomerase inhibition and DNA damage, we investigated genetic events associated with cardiomyopathy and searched for mechanism-based possibilities to alleviate cardiotoxicity. We treated rats at clinically relevant doses of doxorubicin. Histopathology and transmission electron microscopy (TEM) defined cardiac lesions, and transcriptomics unveiled cardiomyopathy-associated gene regulations. Genomic-footprints revealed critical components of Abl1-p53-signaling, and EMSA-assays evidenced Abl1 DNA-binding activity. Gene reporter assays confirmed Abl1 activity on p53-targets while immunohistochemistry/immunofluorescence microscopy demonstrated Abl1, p53&p73 signaling. RESULTS: Doxorubicin treatment caused dose-dependently toxic cardiomyopathy, and TEM evidenced damaged mitochondria and myofibrillar disarray. Surviving cardiomyocytes repressed Parkin-1 and Bnip3-mediated mitophagy, stimulated dynamin-1-like dependent mitochondrial fission and induced anti-apoptotic Bag1 signaling. Thus, we observed induced mitochondrial biogenesis. Transcriptomics discovered heterogeneity in cellular responses with minimal overlap between treatments, and the data are highly suggestive for distinct cardiomyocyte (sub)populations which differed in their resilience and reparative capacity. Genome-wide footprints revealed Abl1 and p53 enriched binding sites in doxorubicin-regulated genes, and we confirmed Abl1 DNA-binding activity in EMSA-assays. Extraordinarily, Abl1 signaling differed in the heart with highly significant regulations of Abl1, p53 and p73 in atrial cardiomyocytes. Conversely, in ventricular cardiomyocytes, Abl1 solely-modulated p53-signaling that was BAX transcription-independent. Gene reporter assays established Abl1 cofactor activity for the p53-reporter PG13-luc, and ectopic Abl1 expression stimulated p53-mediated apoptosis. CONCLUSIONS: The tyrosine kinase Abl1 is of critical importance in doxorubicin induced cardiomyopathy, and we propose its inhibition as means to diminish risk of cardiotoxicity.
Assuntos
Cardiomiopatias , Doxorrubicina , Miócitos Cardíacos , Proteínas Proto-Oncogênicas c-abl , Transdução de Sinais , Proteína Supressora de Tumor p53 , Animais , Doxorrubicina/efeitos adversos , Doxorrubicina/farmacologia , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Proteína Supressora de Tumor p53/metabolismo , Transdução de Sinais/efeitos dos fármacos , Cardiomiopatias/induzido quimicamente , Cardiomiopatias/patologia , Cardiomiopatias/metabolismo , Proteínas Proto-Oncogênicas c-abl/metabolismo , Proteínas Proto-Oncogênicas c-abl/genética , Ventrículos do Coração/patologia , Ventrículos do Coração/efeitos dos fármacos , Átrios do Coração/patologia , Átrios do Coração/efeitos dos fármacos , Átrios do Coração/metabolismo , Morte Celular/efeitos dos fármacos , Masculino , Ratos , Ratos WistarRESUMO
Omecamtiv mecarbil (OM) is a small molecule that has been shown to improve the function of the slow human ventricular myosin (MyHC) motor through a complex perturbation of the thin/thick filament regulatory state of the sarcomere mediated by binding to myosin allosteric sites coupled to inorganic phosphate (Pi) release. Here, myofibrils from samples of human left ventricle (ß-slow MyHC-7) and left atrium (α-fast MyHC-6) from healthy donors were used to study the differential effects of µmolar [OM] on isometric force in relaxing conditions (pCa 9.0) and at maximal (pCa 4.5) or half-maximal (pCa 5.75) calcium activation, both under control conditions (15 °C; equimolar DMSO; contaminant inorganic phosphate [Pi] ~170 µM) and in the presence of 5 mM [Pi]. The activation state and OM concentration within the contractile lattice were rapidly altered by fast solution switching, demonstrating that the effect of OM was rapid and fully reversible with dose-dependent and myosin isoform-dependent features. In MyHC-7 ventricular myofibrils, OM increased submaximal and maximal Ca2+-activated isometric force with a complex dose-dependent effect peaking (40% increase) at 0.5 µM, whereas in MyHC-6 atrial myofibrils, it had no effect or-at concentrations above 5 µM-decreased the maximum Ca2+-activated force. In both ventricular and atrial myofibrils, OM strongly depressed the kinetics of force development and relaxation up to 90% at 10 µM [OM] and reduced the inhibition of force by inorganic phosphate. Interestingly, in the ventricle, but not in the atrium, OM induced a large dose-dependent Ca2+-independent force development and an increase in basal ATPase that were abolished by the presence of millimolar inorganic phosphate, consistent with the hypothesis that the widely reported Ca2+-sensitising effect of OM may be coupled to a change in the state of the thick filaments that resembles the on-off regulation of thin filaments by Ca2+. The complexity of this scenario may help to understand the disappointing results of clinical trials testing OM as inotropic support in systolic heart failure compared with currently available inotropic drugs that alter the calcium signalling cascade.
Assuntos
Contração Miocárdica , Miofibrilas , Ureia , Humanos , Ureia/análogos & derivados , Ureia/farmacologia , Miofibrilas/metabolismo , Miofibrilas/efeitos dos fármacos , Contração Miocárdica/efeitos dos fármacos , Cálcio/metabolismo , Miocárdio/metabolismo , Isoformas de Proteínas/metabolismo , Miosinas/metabolismo , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/metabolismo , Masculino , Miosinas Cardíacas/metabolismo , Feminino , AdultoRESUMO
INTRODUCTION: We have previously reported that genetically positive patients have a more profound early decrease in provocable left ventricular outflow tract gradient compared to genetically negative patients utilizing mavacamten in the first 12 weeks of therapy. METHODS AND RESULTS: In this current analysis, we found that genetically positive patients have less favorable remodeling as measured by left ventricular wall thickness regression when evaluated long-term as compared to genetically negative patients, despite an overall better early response to mavacamten. The majority of genetically positive patients were maintained on only 2.5 mg of mavacamten due to early robust response. CONCLUSION: We hypothesize that this lower dosing attenuated the long-term benefit of mavacamten in genetically positive patients. We believe that the long-term benefit of mavacamten on positive cardiac remodeling is dose-dependent and not solely related to the magnitude of left ventricular outflow gradient decrease.
Assuntos
Remodelação Ventricular , Humanos , Remodelação Ventricular/efeitos dos fármacos , Remodelação Ventricular/genética , Masculino , Feminino , Seguimentos , Pessoa de Meia-Idade , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/efeitos dos fármacos , Relação Dose-Resposta a Droga , Resultado do Tratamento , Fatores de Tempo , Benzilaminas , Uracila/análogos & derivadosRESUMO
In rats decreased bioavailability of nitric oxide induces oxidative stress and right heart failure. Oxidative stress can activate matrix metalloproteinase-2 (MMP2). We addressed the question whether increasing oxidative defense by administration of the SOD mimetic Tempol or direct inhibition of MMP2 activity by SB-3CT mitigates right heart failure. Rats received l-NAME for four weeks and during week three and four treatment groups received either Tempol or SB-3CT in addition. After four weeks heart function was analyzed by echocardiography, organ weights and expression of NPPB and COL1A1 were analyzed, oxidative stress was monitored by DHE-staining and MMP2 activity was quantified by proteolytic auto-activation, zymography, and troponin I degradation. l-NAME induced oxidative stress and MMP2 activity stronger in the right ventricle than in the left ventricle. Troponin I, a MMP2 substrate, was degraded in right ventricles. Tempol reduced oxidative stress and preferentially affected the expression of fibrotic genes (i.e. COL1A1) and fibrosis. Tempol and SB-3CT mitigated right but not left ventricular hypertrophy. Neither SB-3CT nor Tempol alone strongly improved right ventricular function. In conclusion, both MMP2 activity and oxidative stress contribute to right ventricular failure but neither is MMP2 activation linked to oxidative stress nor does oxidative stress and MMP2 activity have common targets.
Assuntos
Óxidos N-Cíclicos , Insuficiência Cardíaca , Metaloproteinase 2 da Matriz , NG-Nitroarginina Metil Éster , Estresse Oxidativo , Marcadores de Spin , Animais , Metaloproteinase 2 da Matriz/metabolismo , Metaloproteinase 2 da Matriz/genética , Ratos , Insuficiência Cardíaca/tratamento farmacológico , Insuficiência Cardíaca/metabolismo , Insuficiência Cardíaca/induzido quimicamente , Insuficiência Cardíaca/patologia , Estresse Oxidativo/efeitos dos fármacos , Óxidos N-Cíclicos/farmacologia , NG-Nitroarginina Metil Éster/farmacologia , Masculino , Colágeno Tipo I/metabolismo , Fibrose , Cadeia alfa 1 do Colágeno Tipo I , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/metabolismo , Troponina I/metabolismo , Inibidores de Metaloproteinases de Matriz/farmacologia , Modelos Animais de Doenças , Compostos Heterocíclicos com 1 Anel , SulfonasRESUMO
There is insufficient data on systemic embolic events (SSEs) in patients with ischemic left ventricular aneurysm (LVA) concerning the impact of anticoagulation therapy. In this retrospective cohort study with 1043 patients with ischemic LVA, SSEs occurred in 7.2% over 2.4 years. After adjusting for relevant factors, the use of anticoagulants was independently associated with a lower incidence of SSE (3.1% vs. 9.0%, P < 0.001; subdistribution hazard ratios (SHR) 0.21, 95% confidence intervals (CI) 0.10-0.44, P < 0.001), with no significant difference in net adverse clinical events (NACEs) (10.6% vs. 13.3%, P = 0.225). Specifically, anticoagulation in patients with apical segment akinesis significantly reduced SSEs (3.9% vs. 13.6%, P = 0.002) and NACE rates (7.8% vs. 19.4%, P = 0.002). Major bleeding rates did not significantly differ between groups (5.6% vs. 3.5%, P = 0.111). These findings highlight the SSE risk in ischemic LVA and suggest potential benefits of anticoagulation, particularly in those with apical segment akinesis. These findings need to be validated in independent datasets.
Assuntos
Anticoagulantes , Aneurisma Cardíaco , Humanos , Estudos Retrospectivos , Anticoagulantes/uso terapêutico , Masculino , Feminino , Idoso , Pessoa de Meia-Idade , Prognóstico , Aneurisma Cardíaco/tratamento farmacológico , Aneurisma Cardíaco/epidemiologia , Ventrículos do Coração/patologia , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/fisiopatologia , Isquemia Miocárdica/tratamento farmacológico , Isquemia Miocárdica/epidemiologia , Fatores de Risco , Hemorragia/induzido quimicamente , Hemorragia/epidemiologia , Embolia/epidemiologia , Embolia/tratamento farmacológicoRESUMO
BACKGROUND: Persistent mineralocorticoid receptor activation is a pathologic response in type 2 diabetes and chronic kidney disease. Whereas mineralocorticoid receptor antagonists are beneficial in reducing cardiovascular complications, direct mechanistic pathways for these effects in humans are lacking. METHODS: The MAGMA trial (Mineralocorticoid Receptor Antagonism Clinical Evaluation in Atherosclerosis) was a randomized, double-blind, placebo-controlled trial in patients with high-risk type 2 diabetes with chronic kidney disease (not receiving dialysis) on maximum tolerated renin-angiotensin system blockade. The primary end point was change in thoracic aortic wall volume, expressed as absolute or percent value (ΔTWV or ΔPWV), using 3T magnetic resonance imaging at 12 months. Secondary end points were changes in left ventricle (LV) mass; LV fibrosis, measured as a change in myocardial native T1; and 24-hour ambulatory and central aortic blood pressures. Tertiary end points included plasma proteomic changes in 7596 plasma proteins using an aptamer-based assay. RESULTS: A total of 79 patients were randomized to placebo (n=42) or 25 mg of spironolactone daily (n=37). After a modified intent-to-treat, including available baseline data of study end points, patients who completed the trial protocol were included in the final analyses. At the 12-month follow-up, the average change in PWV was 7.1±10.7% in the placebo group and 0.87±10.0% in the spironolactone group (P=0.028), and ΔTWV was 1.2±1.7 cm3 in the placebo group and 0.037±1.9 cm3 in the spironolactone group (P=0.022). Change in LV mass was 3.1±8.4 g in the placebo group and -5.8±8.4 g in the spironolactone group (P=0.001). Changes in LV T1 values were significantly different between the placebo and spironolactone groups (26.0±41.9 ms in the placebo group versus a decrease of -10.1±36.3 ms in the spironolactone group; P=6.33×10-4). Mediation analysis revealed that the spironolactone effect on thoracic aortic wall volume and myocardial mass remained significant after adjustment for ambulatory and central blood pressures. Proteomic analysis revealed a dominant effect of spironolactone on pathways involving oxidative stress, inflammation, and leukocyte activation. CONCLUSIONS: Among patients with diabetes with moderate to severe chronic kidney disease at elevated cardiovascular risk, treatment with spironolactone prevented progression of aortic wall volume and resulted in regression of LV mass and favorable alterations in native T1, suggesting amelioration of left-ventricular fibrosis. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02169089.
Assuntos
Diabetes Mellitus Tipo 2 , Fibrose , Antagonistas de Receptores de Mineralocorticoides , Insuficiência Renal Crônica , Espironolactona , Humanos , Antagonistas de Receptores de Mineralocorticoides/uso terapêutico , Masculino , Feminino , Pessoa de Meia-Idade , Método Duplo-Cego , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/complicações , Idoso , Insuficiência Renal Crônica/tratamento farmacológico , Insuficiência Renal Crônica/metabolismo , Insuficiência Renal Crônica/complicações , Espironolactona/uso terapêutico , Progressão da Doença , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/patologia , Ventrículos do Coração/efeitos dos fármacos , Resultado do TratamentoRESUMO
BACKGROUNDS: A soluble guanylyl cyclase stimulator vericiguat has been shown to reduce cardiovascular mortality or hospitalization for heart failure in patients with worsening heart failure in the VICTORIA study. However, little is known about the effects of vericiguat on biventricular structure and function. METHODS AND RESULTS: A retrospective analysis of 63 consecutive patients with heart failure with reduced ejection fraction (HFrEF) who were treated with vericiguat was performed. Clinical data and echocardiographic parameters were compared between baseline and follow-up after the initiation of vericiguat. The median follow-up duration was 266 days. Treatment with vericiguat significantly reduced the plasma BNP levels (log-transformed) compared to baseline (2.46 ± 0.51 vs. 2.14 ± 0.58, p < 0.0001). Left ventricular end-diastolic volume index and left ventricular end-systolic volume index were significantly reduced (LVEDVI, 113.5 ± 46.3 vs. 103.6 ± 51.0, p = 0.0056; LVESVI, 82.0 ± 41.9 vs. 72.8 ± 44.7, p = 0.0077; respectively). The tricuspid annular plane systolic excursion to pulmonary artery systolic pressure (TAPSE/PASP) ratio, an indicator of right ventricle-pulmonary artery (RV-PA) coupling, increased significantly after the treatment (0.56 ± 0.29 vs. 0.92 ± 1.09, p < 0.0001). Univariate and multivariate analyses showed that the treatment effects of vericiguat on BNP levels, LV reverse remodeling, and RV-PA coupling were not correlated with the achievement of the quadruple therapy with beta-blockers, renin-angiotensin system inhibitors, mineralocorticoid inhibitors, and sodium-glucose cotransporter-2 inhibitors, nor with worsening heart failure (WHF). CONCLUSION: Treatment with vericiguat improved adverse LV remodeling and RV-PA uncoupling in HFrEF patients. These effects were independent of WHF and achieving the quadruple therapy. Patients with HFrEF may benefit from early initiation of vericiguat to prevent biventricular adverse remodeling.
Assuntos
Insuficiência Cardíaca , Artéria Pulmonar , Pirimidinas , Volume Sistólico , Humanos , Masculino , Insuficiência Cardíaca/tratamento farmacológico , Insuficiência Cardíaca/fisiopatologia , Feminino , Estudos Retrospectivos , Volume Sistólico/efeitos dos fármacos , Volume Sistólico/fisiologia , Idoso , Pessoa de Meia-Idade , Artéria Pulmonar/efeitos dos fármacos , Artéria Pulmonar/fisiopatologia , Artéria Pulmonar/diagnóstico por imagem , Resultado do Tratamento , Pirimidinas/uso terapêutico , Seguimentos , Ventrículos do Coração/fisiopatologia , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/efeitos dos fármacos , Compostos Heterocíclicos com 2 AnéisRESUMO
BACKGROUND: Cardiovascular disease remains one of the leading causes of death globally. Myocardial ischemia and infarction, in particular, frequently cause disturbances in cardiac electrical activity that can trigger ventricular arrhythmias. We aimed to investigate whether catestatin, an endogenous catecholamine-inhibiting peptide, ameliorates myocardial ischemia-induced ventricular arrhythmias in rats and the underlying ionic mechanisms. METHODS AND RESULTS: Adult male Sprague-Dawley rats were randomly divided into control and catestatin groups. Ventricular arrhythmias were induced by ligation of the left anterior descending coronary artery and electrical stimulation. Action potential, transient outward potassium current, delayed rectifier potassium current, inward rectifying potassium current, and L-type calcium current (ICa-L) of rat ventricular myocytes were recorded using a patch-clamp technique. Catestatin notably reduced ventricular arrhythmia caused by myocardial ischemia/reperfusion and electrical stimulation of rats. In ventricular myocytes, catestatin markedly shortened the action potential duration of ventricular myocytes, which was counteracted by potassium channel antagonists TEACl and 4-AP, and ICa-L current channel agonist Bay K8644. In addition, catestatin significantly increased transient outward potassium current, delayed rectifier potassium current, and inward rectifying potassium current density in a concentration-dependent manner. Catestatin accelerated the activation and decelerated the inactivation of the transient outward potassium current channel. Furthermore, catestatin decreased ICa-L current density in a concentration-dependent manner. Catestatin also accelerated the inactivation of the ICa-L channel and slowed down the recovery of ICa-L from inactivation. CONCLUSIONS: Catestatin enhances the activity of transient outward potassium current, delayed rectifier potassium current, and inward rectifying potassium current, while suppressing the ICa-L in ventricular myocytes, leading to shortened action potential duration and ultimately reducing the ventricular arrhythmia in rats.
Assuntos
Potenciais de Ação , Cromogranina A , Miócitos Cardíacos , Fragmentos de Peptídeos , Ratos Sprague-Dawley , Animais , Masculino , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Cromogranina A/farmacologia , Cromogranina A/metabolismo , Potenciais de Ação/efeitos dos fármacos , Fragmentos de Peptídeos/farmacologia , Canais de Cálcio Tipo L/metabolismo , Canais de Cálcio Tipo L/efeitos dos fármacos , Arritmias Cardíacas/fisiopatologia , Arritmias Cardíacas/prevenção & controle , Arritmias Cardíacas/metabolismo , Antiarrítmicos/farmacologia , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/metabolismo , Ventrículos do Coração/fisiopatologia , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Canais de Potássio Corretores do Fluxo de Internalização/efeitos dos fármacos , Modelos Animais de Doenças , Bloqueadores dos Canais de Potássio/farmacologia , Ratos , Técnicas de Patch-Clamp , Canais de Potássio de Retificação Tardia/metabolismo , Canais de Potássio de Retificação Tardia/efeitos dos fármacos , Canais de Potássio/metabolismo , Canais de Potássio/efeitos dos fármacosRESUMO
Importance: Increases in pulmonary capillary wedge pressure (PCWP) during exercise reduce pulmonary artery (PA) compliance, increase pulsatile right ventricular (RV) afterload, and impair RV-PA coupling in patients with heart failure with preserved ejection fraction (HFpEF). The effects of the sodium-glucose cotransporter 2 (SGLT2) inhibitor dapagliflozin on pulmonary vascular properties and RV-PA coupling are unknown. Objective: To test the effect of dapagliflozin on right ventricular performance and pulmonary vascular load during exertion in HFpEF. Design, Setting, and Participants: Evaluation of the Cardiac and Metabolic Effects of Dapagliflozin in Heart Failure With Preserved Ejection Fraction (CAMEO-DAPA) randomized clinical trial demonstrated improvement in PCWP at rest and exercise over 24 weeks with dapagliflozin compared with placebo with participants recruited between February 2021 and May 2022. This secondary analysis evaluates the effects of dapagliflozin on pulsatile pulmonary vascular load and RV-PA coupling using simultaneous echocardiography and high-fidelity invasive hemodynamic testing with exercise. This was a single-center study including patients with hemodynamically confirmed HFpEF with exercise PCWP of 25 mm Hg or greater. Interventions: Dapagliflozin or placebo for 24 weeks. Main Outcomes and Measures: Pulsatile pulmonary vascular load (PA compliance and elastance) and right ventricular performance (PA pulsatility index, RV systolic velocity [s']/PA mean) during rest and exercise. Results: Among 37 randomized participants (mean [SD] age, 67.4 [8.5] years; 25 female [65%]; mean [SD] body mass index, 34.9 [6.7]; calculated as weight in kilograms divided by height in meters squared), there was no effect of dapagliflozin on PA loading or RV-PA interaction at rest. However, with exercise, dapagliflozin improved PA compliance (placebo-corrected mean difference, 0.57 mL/mm Hg; 95% CI, 0.11-1.03 mL/mm Hg; P = .02) and decreased PA elastance (stiffness; -0.17 mm Hg/mL; 95% CI, -0.28 to -0.07 mm Hg/mL; P = .001). RV function during exercise improved, with increase in PA pulsatility index (0.33; 95% CI, 0.08-0.59; P = .01) and increase in exercise RV s' indexed to PA pressure (0.09 cm·s-1/mm Hg; 95% CI, 0.02-0.16 cm·s-1/mm Hg; P = .01). Improvements in pulsatile RV load and RV-PA coupling were correlated with reduction in right atrial (RA) pressure (PA elastance Pearson r = 0.55; P =.008; RV s'/PA elastance Pearson r = -0.60; P =.002) and PCWP (PA elastance Pearson r = 0.58; P <.001; RV s'/PA elastance Pearson r = -0.47; P = .02). Dapagliflozin increased resistance-compliance time (dapagliflozin, median [IQR] change, 0.06 [0.03-0.15] seconds; placebo, median [IQR] change, 0.01 [-0.02 to 0.05] seconds; P =.046), resulting in higher PA compliance for any exercise pulmonary vascular resistance. Conclusions and Relevance: Results of this randomized clinical trial reveal that treatment with dapagliflozin for 24 weeks reduced pulsatile pulmonary vascular load and enhanced dynamic RV-PA interaction during exercise in patients with HFpEF, findings that are related to the magnitude of PCWP reduction. Benefits on dynamic right ventricular-pulmonary vascular coupling may partially explain the benefits of SGLT2 inhibitors in HFpEF. Trial Registration: ClinicalTrials.gov Identifier: NCT04730947.
Assuntos
Compostos Benzidrílicos , Glucosídeos , Insuficiência Cardíaca , Inibidores do Transportador 2 de Sódio-Glicose , Volume Sistólico , Humanos , Compostos Benzidrílicos/uso terapêutico , Compostos Benzidrílicos/farmacologia , Insuficiência Cardíaca/fisiopatologia , Insuficiência Cardíaca/tratamento farmacológico , Glucosídeos/uso terapêutico , Feminino , Masculino , Volume Sistólico/efeitos dos fármacos , Volume Sistólico/fisiologia , Idoso , Inibidores do Transportador 2 de Sódio-Glicose/uso terapêutico , Inibidores do Transportador 2 de Sódio-Glicose/farmacologia , Pessoa de Meia-Idade , Função Ventricular Direita/efeitos dos fármacos , Função Ventricular Direita/fisiologia , Pressão Propulsora Pulmonar/efeitos dos fármacos , Artéria Pulmonar/fisiopatologia , Artéria Pulmonar/efeitos dos fármacos , Ecocardiografia , Ventrículos do Coração/fisiopatologia , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/diagnóstico por imagemRESUMO
Unlike humans and other mammals, zebrafish demonstrate a remarkable capacity to regenerate their injured hearts throughout life. Mitochondrial fatty acid ß-oxidation (FAO) contributes to major energy demands of the adult hearts under physiological conditions; however, its functions in regulating cardiac regeneration and the underlying mechanisms are not completely understood. Different strategies targeting FAO have yield mixed outcomes. Here, we demonstrated that pharmacological inhibition of mitochondrial FAO with mildronate (MD) caused lipid accumulation in zebrafish larvae and suppressed ventricle regeneration. MD treatment impeded cardiogenic factor reactivation and cardiomyocyte (CM) proliferation, and impaired ventricle regeneration could be rescued by exogenous l-carnitine supplementation. Moreover, compared with the ablated hearts of wild-type fish, ventricle regeneration, cardiogenic factor reactivation and CM proliferation were significantly blocked in the ablated hearts of carnitine palmitoyltransferase-1b (cpt1b) knockout zebrafish. Further experiments suggested that NF-κB signaling and increased inflammation may be involved in the impediment of ventricle regeneration caused by systemic mitochondrial FAO inhibition. Overall, our study demonstrates the essential roles of mitochondrial FAO in zebrafish ventricle regeneration and reaffirms the sophisticated and multifaceted roles of FAO in heart regeneration with regard to different injury models and means of FAO inhibition.
Assuntos
Ácidos Graxos , Ventrículos do Coração , Oxirredução , Regeneração , Peixe-Zebra , Animais , Carnitina O-Palmitoiltransferase/genética , Carnitina O-Palmitoiltransferase/metabolismo , Proliferação de Células/efeitos dos fármacos , Ácidos Graxos/metabolismo , Ventrículos do Coração/metabolismo , Ventrículos do Coração/efeitos dos fármacos , Metilidrazinas/farmacologia , Mitocôndrias/metabolismo , Mitocôndrias/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/efeitos dos fármacos , NF-kappa B/metabolismo , Oxirredução/efeitos dos fármacos , Regeneração/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismoRESUMO
BACKGROUND: The risk of arrhythmia is usually assessed by the length of the corrected QT interval (QTc) when patients use antipsychotics. Prolonged QTc intervals are thought to increase the probability of malignant ventricular arrhythmias, and if we focus only on the QTc interval, we may be influenced by a single factor and make decisions that are not conducive to effective treatment. The index of cardiac electrophysiological balance (iCEB) is considered more valuable than the QTc for predicting drug-induced arrhythmias. It has been used in clinical practice, but no studies have observed changes in this index after the use of antipsychotics. OBJECTIVE: To investigate the changes in ventricular repolarization indices and the occurrence of arrhythmias in patients who have been using antipsychotic drugs for a long time, to compare the changes in iCEBc and QTc and to predict abnormal iCEBc values. METHODS: Patients with schizophrenia who had been hospitalized for more than 4 years and who were receiving atypical antipsychotics underwent a 12-lead synchronized electrocardiogram (ECG) every 2-4 weeks. The baseline data were measured at admission, defined as the baseline (time0), and the most obvious abnormal changes in ventricular depolarization and repolarization measured every 12 months were one-year follow-up (time1), two-year follow-up (time2), three-year follow-up (time3), and four-year follow-up (time4). Repeated measures analysis of variance was used for comparisons. The types and doses of drugs taken at 5 time points were recorded and converted into chlorpromazine equivalents for comparison. The incidence of arrhythmia during the observation cycle was recorded. RESULTS: The patients had been treated with antipsychotic medication for 4 years, and the duration of the QRS wave was longer in males than in females. TpTe, TpTe/QRS, TpTe/QT, TpTe/QTc, iCEB, and iCEBc increased significantly with hospital stay, while TpTe, TpTe/QRS, TpTe/QT, and TpTe/QTc exhibited more obvious changes in these indicators in female patients (P < 0.01). The changes in iCEB and iCEBc were more significant in males (P < 0.01). The incidences of arrhythmia (arrhythmic events included premature ventricular beats and premature atrial beats) within 5 time points were 2.5%, 6.25%, 6.25%, 6.25% and 5%, respectively. More than 90% of patients treated with antipsychotics did not have any arrhythmias. No TdP syncope or other cardiovascular symptoms were found in any of the patients. CONCLUSION: After long-term use of antipsychotics, the ventricular repolarization index gradually increased with time. The new ventricular repolarization indices iCEB and iCEBc were more sensitive than the QTc at predicting arrhythmia. According to the abnormal QTc values in men and women, we predict that the abnormal value of the iCEBc in males is 4.528 and that in females is 5.315.
Assuntos
Antipsicóticos , Arritmias Cardíacas , Eletrocardiografia , Esquizofrenia , Humanos , Antipsicóticos/efeitos adversos , Feminino , Masculino , Eletrocardiografia/efeitos dos fármacos , Adulto , Pessoa de Meia-Idade , Esquizofrenia/tratamento farmacológico , Esquizofrenia/fisiopatologia , Arritmias Cardíacas/induzido quimicamente , Arritmias Cardíacas/fisiopatologia , Ventrículos do Coração/fisiopatologia , Ventrículos do Coração/efeitos dos fármacos , SeguimentosRESUMO
BACKGROUND: Vitamin K antagonists (VKAs) are the recommended first-line treatment for left ventricular thrombus (LVT); however, direct oral anticoagulants (DOACs) have been considered an alternative therapy. OBJECTIVES: To evaluate the efficacy and safety of DOACs compared with VKAs therapy in patients with LVT. METHODS: PubMed, Embase, and Cochrane were systematically searched for randomized clinical trials or cohort studies that compared DOACs versus VKAs for LVT. Risk ratios (RRs) were computed for binary endpoints, with 95% confidence intervals (95% CIs). Statistical significance was defined as p value < 0.05. RESULTS: A total of 4 randomized clinical trials and 29 cohort studies were included, with 4,450 patients assigned to either DOACs or VKAs. There was no significant difference between groups for stroke or systemic embolic (SSE) events (RR 0.84; 95% CI 0.65 to 1.07; p = 0.157), stroke (RR 0.73; 95% CI 0.48 to 1.11; p = 0.140), systemic embolic (SE) events (RR 0.69; 95% CI 0.40 to 1.17; p = 0.166), thrombus resolution (RR 1.05; 95% CI 0.99 to 1.11; p = 0.077), any bleeding (RR 0.78; 95% CI 0.60 to 1.00; p = 0.054), clinically relevant bleeding (RR 0.69; 95% CI 0.46 to 1.03; p = 0.066), minor bleeding (RR 0.73; 95% CI 0.43 to 1.23; p = 0.234), major bleeding (RR 0.87; 95% CI 0.42 to 1.80; p = 0.705), and all-cause mortality (RR 1.05; 95% CI 0.79 to 1.39; p = 0.752). Compared with VKAs, rivaroxaban significantly reduced SSE events (RR 0.35; 95% CI 0.16 to 0.91; p = 0.029) and SE events (RR 0.39; 95% CI 0.16 to 0.95; p = 0.037). CONCLUSIONS: DOACs had a similar rate of thromboembolic and hemorrhagic events, as well as thrombus resolution, compared to VKAs in the treatment of LVTs. Rivaroxaban therapy had a significant reduction in thromboembolic events, compared to VKAs.
Assuntos
Anticoagulantes , Ventrículos do Coração , Trombose , Vitamina K , Humanos , Vitamina K/antagonistas & inibidores , Anticoagulantes/uso terapêutico , Trombose/tratamento farmacológico , Ventrículos do Coração/efeitos dos fármacos , Administração Oral , Hemorragia/induzido quimicamente , Cardiopatias/tratamento farmacológico , Resultado do Tratamento , Acidente Vascular Cerebral/tratamento farmacológico , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
Pulmonary arterial hypertension (PAH) is characterised by an increase in mean pulmonary arterial pressure and a compromised the right ventricle (RV), together with progression to heart failure and premature death. Studies have evaluated the role of melatonin as a promising therapeutic strategy for PAH. The objective of this study was to evaluate melatonin's effects on oxidative stress and on the TLR4/NF-kß inflammatory pathway in the RV of rats with PAH. Male Wistar rats were divided into the following groups: control, monocrotaline (MCT), and monocrotaline plus melatonin groups. These two last groups received one intraperitoneal injection of MCT (60 mg/kg) on the first day of experimental protocol. The monocrotaline plus melatonin group received 10 mg/kg/day of melatonin by gavage for 21 days. Echocardiographic analysis was performed, and the RV was collected for morphometric analysis oxidative stress and molecular evaluations. The main findings of the present study were that melatonin administration attenuated the reduction in RV function that was induced by monocrotaline, as assessed by TAPSE. In addition, melatonin prevented RV diastolic area reduction caused by PAH. Furthermore, animals treated with melatonin did not show an increase in ROS levels or in NF-kß expression. In addition, the monocrotaline plus melatonin group showed a reduction in TLR4 expression when compared with control and monocrotaline groups. To our knowledge, this is the first study demonstrating a positive effect of melatonin on the TLR4/NF-kß pathway in the RV of rats with PAH. In this sense, this study makes it possible to think of melatonin as a possible ally in mitigating RV alterations caused by PAH.
Assuntos
Ventrículos do Coração , Melatonina , Monocrotalina , Estresse Oxidativo , Ratos Wistar , Transdução de Sinais , Receptor 4 Toll-Like , Animais , Melatonina/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Receptor 4 Toll-Like/metabolismo , Receptor 4 Toll-Like/genética , Masculino , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/patologia , Ventrículos do Coração/metabolismo , Monocrotalina/toxicidade , Transdução de Sinais/efeitos dos fármacos , Hipertensão Arterial Pulmonar/tratamento farmacológico , Hipertensão Arterial Pulmonar/metabolismo , Hipertensão Arterial Pulmonar/patologia , NF-kappa B/metabolismo , Inflamação/patologia , Inflamação/tratamento farmacológico , Ratos , Hipertensão Pulmonar/tratamento farmacológico , Hipertensão Pulmonar/metabolismo , Hipertensão Pulmonar/patologia , Espécies Reativas de Oxigênio/metabolismoRESUMO
Human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs) have found utility for conducting in vitro drug screening and disease modelling to gain crucial insights into pharmacology or disease phenotype. However, diseases such as atrial fibrillation, affecting >33 M people worldwide, demonstrate the need for cardiac subtype-specific cells. Here, we sought to investigate the base characteristics and pharmacological differences between commercially available chamber-specific atrial or ventricular hiPSC-CMs seeded onto ultra-thin, flexible PDMS membranes to simultaneously measure contractility in a 96 multi-well format. We investigated the effects of GPCR agonists (acetylcholine and carbachol), a Ca2+ channel agonist (S-Bay K8644), an HCN channel antagonist (ivabradine) and K+ channel antagonists (4-AP and vernakalant). We observed differential effects between atrial and ventricular hiPSC-CMs on contractile properties including beat rate, beat duration, contractile force and evidence of arrhythmias at a range of concentrations. As an excerpt of the compound analysis, S-Bay K8644 treatment showed an induced concentration-dependent transient increase in beat duration of atrial hiPSC-CMs, whereas ventricular cells showed a physiological increase in beat rate over time. Carbachol treatment produced marked effects on atrial cells, such as increased beat duration alongside a decrease in beat rate over time, but only minimal effects on ventricular cardiomyocytes. In the context of this chamber-specific pharmacology, we not only add to contractile characterization of hiPSC-CMs but propose a multi-well platform for medium-throughput early compound screening. Overall, these insights illustrate the key pharmacological differences between chamber-specific cardiomyocytes and their application on a multi-well contractility platform to gain insights for in vitro cardiac liability studies and disease modelling.
Assuntos
Átrios do Coração , Ventrículos do Coração , Células-Tronco Pluripotentes Induzidas , Contração Miocárdica , Miócitos Cardíacos , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/fisiologia , Humanos , Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Átrios do Coração/efeitos dos fármacos , Átrios do Coração/citologia , Contração Miocárdica/efeitos dos fármacos , Contração Miocárdica/fisiologia , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/citologia , Receptores Acoplados a Proteínas G/metabolismo , Receptores Acoplados a Proteínas G/agonistas , Desenvolvimento de Medicamentos/métodos , Canais Iônicos/efeitos dos fármacos , Células Cultivadas , Avaliação Pré-Clínica de Medicamentos/métodos , Carbacol/farmacologia , Sistemas MicrofisiológicosRESUMO
AIMS: Direct oral anticoagulants (DOACs) are increasingly used off-label to treat patients with left ventricular thrombus (LVT). We analysed available meta-data comparing DOACs and vitamin K antagonists (VKAs) for efficacy and safety. METHODS: We conducted a systematic search and meta-analysis of observational and randomized data comparing DOACs vs. VKAs in patients with LVT. Endpoints of interest were stroke or systemic embolism, thrombus resolution, all-cause death, and a composite bleeding endpoint. Estimates were pooled using a random-effects model meta-analysis, and their robustness was investigated using sensitivity and influential analyses. RESULTS: We identified 22 articles (18 observational studies, 4 small randomized clinical trials) reporting on a total of 3587 patients (2489 VKA vs. 1098 DOAC therapy). The pooled estimates for stroke or systemic embolism [odds ratio (OR): 0.81; 95% confidence interval (CI): 0.57, 1.15] and thrombus resolution (OR: 1.12; 95% CI: 0.86, 1.46) were comparable, and there was low heterogeneity overall across the included studies. The use of DOACs was associated with lower odds of all-cause death (OR: 0.65; 95% CI: 0.46, 0.92) and a composite bleeding endpoint (OR: 0.67; 95% CI: 0.47, 0.97). A risk of bias was evident particularly for observational reports, with some publication bias suggested in funnel plots. CONCLUSION: In this comprehensive analysis of mainly observational data, the use of DOACs was not associated with a significant difference in stroke or systemic embolism, or thrombus resolution, compared with VKA therapy. The use of DOACs was associated with a lower rate of all-cause death and fewer bleeding events. Adequately sized randomized clinical trials are needed to confirm these findings, which could allow a wider adoption of DOACs in patients with LVT.
Assuntos
Cardiopatias , Hemorragia , Trombose , Humanos , Administração Oral , Trombose/mortalidade , Trombose/tratamento farmacológico , Trombose/prevenção & controle , Trombose/diagnóstico , Hemorragia/induzido quimicamente , Resultado do Tratamento , Fatores de Risco , Cardiopatias/mortalidade , Cardiopatias/diagnóstico , Cardiopatias/tratamento farmacológico , Cardiopatias/complicações , Anticoagulantes/efeitos adversos , Anticoagulantes/administração & dosagem , Ventrículos do Coração/efeitos dos fármacos , Feminino , Medição de Risco , Masculino , Acidente Vascular Cerebral/mortalidade , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/prevenção & controle , Idoso , Inibidores do Fator Xa/efeitos adversos , Inibidores do Fator Xa/administração & dosagem , Vitamina K/antagonistas & inibidores , Pessoa de Meia-IdadeRESUMO
AIMS: Anthracycline chemotherapy (AC) for breast cancer can cause cancer therapy-related cardiac dysfunction (CTRCD) with resultant heart failure, traditionally defined as a reduction in left ventricular (LV) ejection fraction on echocardiography. In recent years, global longitudinal systolic strain (GLS) has been used to identify subclinical cardiac dysfunction prior to development of overt CTRCD. Recent harmonized guidelines have incorporated GLS into definitions for CTRCD to identify cardiac dysfunction and inform decisions regarding cardioprotective strategies. METHODS AND RESULTS: We evaluated subclinical dysfunction in breast cancer patients treated with AC and determined the echocardiographic and patient factors associated with significant GLS changes. One hundred fourteen HER2 negative patients treated with AC were prospectively recruited and underwent serial echocardiograms (LVEF and LVGLS) at three time points (prior to AC, 3 months, and 1 year). CTRCD was defined as an asymptomatic reduction in LVEF of 10% or symptomatic drop of 5% to LVEF <53%. Subclinical LV dysfunction was defined as a reduction of ≥10% in GLS compared with baseline, recognizing that this cut off identified an 'at risk cohort' rather than patients with established CTRCD. No participant demonstrated CTRCD by reduction in LVEF. Forty-three patients (38%) demonstrated a ≥10% relative reduction in GLS at 12 months; 20/43 (47%) had a reduced absolute GLS to <16%, and were older, had hypertension, increased LV mass, lower baseline e' velocity and GLS. GLS ≥20.5% at baseline yielded a sensitivity of 79% and specificity of 87% for a normal GLS (i.e., ≥16%) at 1 year despite a ≥10% reduction from baseline. CONCLUSIONS: We present a stepwise evaluation for subclinical LV dysfunction using both a relative reduction in GLS combined with an absolute reduction in GLS. We believe our findings may re-stratify patients with a high baseline GLS into a lower risk group despite transient relative GLS decrements ≥10%.
Assuntos
Antraciclinas , Neoplasias da Mama , Cardiotoxicidade , Ecocardiografia , Volume Sistólico , Função Ventricular Esquerda , Humanos , Feminino , Antraciclinas/efeitos adversos , Cardiotoxicidade/etiologia , Cardiotoxicidade/diagnóstico , Pessoa de Meia-Idade , Estudos Prospectivos , Ecocardiografia/métodos , Neoplasias da Mama/tratamento farmacológico , Volume Sistólico/fisiologia , Função Ventricular Esquerda/fisiologia , Função Ventricular Esquerda/efeitos dos fármacos , Disfunção Ventricular Esquerda/fisiopatologia , Disfunção Ventricular Esquerda/induzido quimicamente , Disfunção Ventricular Esquerda/diagnóstico , Seguimentos , Ventrículos do Coração/fisiopatologia , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/efeitos dos fármacosRESUMO
Cardiac arrhythmias remain a significant concern with Ibrutinib (IBR), a first-generation Bruton's tyrosine kinase inhibitor (BTKi). Acalabrutinib (ABR), a next-generation BTKi, is associated with reduced atrial arrhythmia events. However, the role of ABR in ventricular arrhythmia (VA) has not been adequately evaluated. Our study aimed to investigate VA vulnerability and ventricular electrophysiology following chronic ABR therapy in male Sprague-Dawley rats utilizing epicardial optical mapping for ventricular voltage and Ca2+ dynamics and VA induction by electrical stimulation in ex-vivo perfused hearts. Ventricular tissues were snap-frozen for protein analysis for sarcoplasmic Ca2+ and metabolic regulatory proteins. The results show that both ABR and IBR treatments increased VA vulnerability, with ABR showing higher VA regularity index (RI). IBR, but not ABR, is associated with the abbreviation of action potential duration (APD) and APD alternans. Both IBR and ABR increased diastolic Ca2+ leak and Ca2+ alternans, reduced conduction velocity (CV), and increased CV dispersion. Decreased SERCA2a expression and AMPK phosphorylation were observed with both treatments. Our results suggest that ABR treatment also increases the risk of VA by inducing proarrhythmic changes in Ca2+ signaling and membrane electrophysiology, as seen with IBR. However, the different impacts of these two BTKi on ventricular electrophysiology may contribute to differences in VA vulnerability and distinct VA characteristics.
Assuntos
Tirosina Quinase da Agamaglobulinemia , Arritmias Cardíacas , Benzamidas , Piperidinas , Ratos Sprague-Dawley , Animais , Benzamidas/farmacologia , Benzamidas/uso terapêutico , Masculino , Ratos , Tirosina Quinase da Agamaglobulinemia/metabolismo , Tirosina Quinase da Agamaglobulinemia/antagonistas & inibidores , Arritmias Cardíacas/metabolismo , Arritmias Cardíacas/induzido quimicamente , Piperidinas/farmacologia , Piperidinas/uso terapêutico , Potenciais de Ação/efeitos dos fármacos , Remodelação Ventricular/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Pirazinas/farmacologia , Cálcio/metabolismo , Adenina/análogos & derivados , Adenina/farmacologia , Adenina/efeitos adversos , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/metabolismo , Ventrículos do Coração/fisiopatologia , Pirimidinas/farmacologia , Sinalização do Cálcio/efeitos dos fármacos , Pirazóis/farmacologiaRESUMO
BACKGROUND: Ibrutinib, a Bruton's tyrosine kinase inhibitor used in cancer therapy, exerts ventricular proarrhythmic effects; however, the underlying mechanisms remain unclear. Excitation-contraction coupling (E-C) disorders are pivotal for the genesis of ventricular arrhythmias (VAs), which arise mainly from the right ventricular outflow tract (RVOT). In this study, we aimed to comprehensively investigate whether ibrutinib regulates the electromechanical activities of the RVOT, leading to enhanced arrhythmogenesis, and explore the underlying mechanisms. METHODS: We utilized conventional microelectrodes to synchronously record electrical and mechanical responses in rabbit RVOT tissue preparations before and after treatment with ibrutinib (10, 50, and 100 nM) and investigated their electromechanical interactions and arrhythmogenesis during programmed electrical stimulation. The fluorometric ratio technique was used to measure intracellular calcium concentration in isolated RVOT myocytes. RESULTS: Ibrutinib (10-100 nM) shortened the action potential duration. Ibrutinib at 100 nM significantly increased pacing-induced ventricular tachycardia (VT) (from 0% to 62.5%, n = 8, p = 0.025). Comparisons between pacing-induced VT and non-VT episodes demonstrated that VT episodes had a greater increase in contractility than that of non-VT episodes (402.1 ± 41.4% vs. 232.4 ± 29.2%, p = 0.003). The pretreatment of ranolazine (10 µM, a late sodium current blocker) prevented the occurrence of ibrutinib-induced VAs. Ibrutinib (100 nM) increased late sodium current, reduced intracellular calcium transients, and enhanced calcium leakage in RVOT myocytes. CONCLUSION: Ibrutinib increased the risk of VAs in the RVOT due to dysregulated electromechanical responses, which can be attenuated by ranolazine or apamin.
Assuntos
Potenciais de Ação , Adenina , Tirosina Quinase da Agamaglobulinemia , Piperidinas , Inibidores de Proteínas Quinases , Animais , Piperidinas/farmacologia , Coelhos , Adenina/análogos & derivados , Adenina/farmacologia , Tirosina Quinase da Agamaglobulinemia/antagonistas & inibidores , Tirosina Quinase da Agamaglobulinemia/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/efeitos adversos , Potenciais de Ação/efeitos dos fármacos , Pirimidinas/farmacologia , Arritmias Cardíacas/induzido quimicamente , Arritmias Cardíacas/fisiopatologia , Masculino , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/fisiopatologia , Cálcio/metabolismo , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Taquicardia Ventricular/fisiopatologia , Pirazóis/farmacologia , Acoplamento Excitação-Contração/efeitos dos fármacosRESUMO
BACKGROUND AND PURPOSE: The canonical Kir6.2/SUR2A ventricular KATP channel is highly ATP-sensitive and remains closed under normal physiological conditions. These channels activate only when prolonged metabolic compromise causes significant ATP depletion and then shortens the action potential to reduce contractile activity. Pharmacological activation of KATP channels is cardioprotective, but physiologically, it is difficult to understand how these channels protect the heart if they only open under extreme metabolic stress. The presence of a second KATP channel population could help explain this. Here, we characterise the biophysical and pharmacological behaviours of a constitutively active Kir6.1-containing KATP channel in ventricular cardiomyocytes. EXPERIMENTAL APPROACH: Patch-clamp recordings from rat ventricular myocytes in combination with well-defined pharmacological modulators was used to characterise these newly identified K+ channels. Action potential recording, calcium (Fluo-4) fluorescence measurements and video edge detection of contractile function were used to assess functional consequences of channel modulation. KEY RESULTS: Our data show a ventricular K+ conductance whose biophysical characteristics and response to pharmacological modulation were consistent with Kir6.1-containing channels. These Kir6.1-containing channels lack the ATP-sensitivity of the canonical channels and are constitutively active. CONCLUSION AND IMPLICATIONS: We conclude there are two functionally distinct populations of ventricular KATP channels: constitutively active Kir6.1-containing channels that play an important role in fine-tuning the action potential and Kir6.2/SUR2A channels that activate with prolonged ischaemia to impart late-stage protection against catastrophic ATP depletion. Further research is required to determine whether Kir6.1 is an overlooked target in Comprehensive in vitro Proarrhythmia Assay (CiPA) cardiac safety screens.
Assuntos
Ventrículos do Coração , Canais KATP , Miócitos Cardíacos , Sarcolema , Animais , Canais KATP/metabolismo , Ventrículos do Coração/metabolismo , Ventrículos do Coração/citologia , Ventrículos do Coração/efeitos dos fármacos , Sarcolema/metabolismo , Sarcolema/efeitos dos fármacos , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Masculino , Ratos , Potenciais de Ação/efeitos dos fármacos , Ratos Sprague-Dawley , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Canais de Potássio Corretores do Fluxo de Internalização/antagonistas & inibidores , Técnicas de Patch-ClampRESUMO
Doxorubicin (DOX), widely used as a chemotherapeutic agent for various cancers, is limited in its clinical utility by its cardiotoxic effects. Despite its widespread use, the precise mechanisms underlying DOX-induced cardiotoxicity at the cellular and molecular levels remain unclear, hindering the development of preventive and early detection strategies. To characterize the cytotoxic effects of DOX on isolated ventricular cardiomyocytes, focusing on the expression of specific microRNAs (miRNAs) and their molecular targets associated with endogenous cardioprotective mechanisms such as the ATP-sensitive potassium channel (KATP), Sirtuin 1 (SIRT1), FOXO1, and GSK3ß. We isolated Guinea pig ventricular cardiomyocytes by retrograde perfusion and enzymatic dissociation. We assessed cell morphology, Reactive Oxygen Species (ROS) levels, intracellular calcium, and mitochondrial membrane potential using light microscopy and specific probes. We determined the miRNA expression profile using small RNAseq and validated it using stem-loop qRT-PCR. We quantified mRNA levels of some predicted and validated molecular targets using qRT-PCR and analyzed protein expression using Western blot. Exposure to 10 µM DOX resulted in cardiomyocyte shortening, increased ROS and intracellular calcium levels, mitochondrial membrane potential depolarization, and changes in specific miRNA expression. Additionally, we observed the differential expression of KATP subunits (ABCC9, KCNJ8, and KCNJ11), FOXO1, SIRT1, and GSK3ß molecules associated with endogenous cardioprotective mechanisms. Supported by miRNA gene regulatory networks and functional enrichment analysis, these findings suggest that DOX-induced cardiotoxicity disrupts biological processes associated with cardioprotective mechanisms. Further research must clarify their specific molecular changes in DOX-induced cardiac dysfunction and investigate their diagnostic biomarkers and therapeutic potential.