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Introduction: Mercury (Hg) is a heavy metal that causes a variety of toxic effects in eukaryotic cells. Previous studies have reported detrimental effects of mercury toxicity in the cardiovascular system. Given the importance of understanding the relationship between Hg and cardiovascular disease, we sought to investigate if the Hg could worsen the myocardial repercussions following ischemic injury. We demonstrated that once mercury toxicity is established, it can influence the outcome of myocardial infarction (MI). Methods: Male Wistar rats received intramuscular injections of either saline (NaCl 0.9%) or mercuric chloride (HgCl2, first dose of 4.6 µg/kg, and subsequent doses of 0.07 µg/kg/day) for 4 weeks. Three weeks post-exposure, we induced transmural infarction in the left ventricle free wall through coronary artery occlusion surgery. Results: ECG recordings obtained from MI groups demonstrated alterations in the rhythm of the heartbeat/heart electrical activity, as expected, including ventricular extrasystoles and ventricular tachycardia. However, the MI group exposed to Hg (MI-Hg) exhibited augmented ventricular extrasystoles and ventricular tachycardia compared to the MI group. Also, Basckó coefficient revealed that the arrhythmic events-after MI-were aggravated by Hg exposure. Discussion: Our results indicate that the significantly increased mortality in MI-Hg groups when compared to MI (21%, MI vs 32%, MI-Hg) is correlated with greater occurrence of arrhythmias. In conclusion, this study further supports the idea that exposure to mercury (Hg) should be recognized as a significant risk factor that exacerbates the impact of cardiac ischemic injury, potentially leading to an increased mortality rate among patients experiencing acute MI.
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Introduction: Clinical studies have shown that low levels of endogenous testosterone are associated with cardiovascular diseases. Considering the intimate connection between oxidative metabolism and myocardial contractility, we determined the effects of testosterone deficiency on the two spatially distinct subpopulations of cardiac mitochondria, subsarcolemmal (SSM) and interfibrillar (IFM). Methods: We assessed cardiac function and cardiac mitochondria structure of SSM and IFM after 12 weeks of testosterone deficiency in male Wistar rats. Results and Discussion: Results show that low testosterone reduced myocardial contractility. Orchidectomy increased total left ventricular mitochondrial protein in the SSM, but not in IFM. The membrane potential, size and internal complexity in the IFM after orchidectomy were higher compared to the SHAM group. However, the rate of oxidative phosphorylation with all substrates in the IFM after orchidectomy was lower compared to the SHAM group. Testosterone replacement restored these changes. In the testosterone-deficient SSM group, oxidative phosphorylation was decreased with palmitoyl-L-carnitine as substrate; however, the mitochondrial calcium retention capacity in IFM was increased. There was no difference in swelling of the mitochondria in either group. These changes in IFM were followed by a reduction in phosphorylated form of AMP-activated protein kinase (p-AMPK-α), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) translocation to mitochondria and decreased mitochondrial transcription factor A (TFAM). Testosterone deficiency increased NADPH oxidase (NOX), angiotensin converting enzyme (ACE) protein expression and reduced mitochondrial antioxidant proteins such as manganese superoxide dismutase (Mn-SOD) and catalase in the IFM. Treatment with apocynin (1.5 mM in drinking water) normalized myocardial contractility and interfibrillar mitochondrial function in the testosterone depleted animals. In conclusion, our findings demonstrate that testosterone deficiency leads to reduced myocardial contractility and impaired cardiac interfibrillar mitochondrial function. Our data suggest the involvement of reactive oxygen species, with a possibility of NOX as an enzymatic source.
Asunto(s)
Mitocondrias Cardíacas , Miocardio , Ratas , Animales , Masculino , Ratas Wistar , Miocardio/metabolismo , Estrés Oxidativo , Testosterona/farmacología , Testosterona/metabolismoRESUMEN
It is well known that cholinergic hypofunction contributes to cardiac pathology, yet, the mechanisms involved remain unclear. Our previous study has shown that genetically engineered model of cholinergic deficit, the vesicular acetylcholine transporter knockdown homozygous (VAChT KDHOM) mice, exhibit pathological cardiac remodeling and a gradual increase in cardiac mass with aging. Given that an increase in cardiac mass is often caused by adrenergic hyperactivity, we hypothesized that VAChT KDHOM mice might have an increase in cardiac norepinephrine (NE) levels. We thus investigated the temporal changes in NE content in the heart from 3-, 6-, and 12-mo-old VAChT mutants. Interestingly, mice with cholinergic hypofunction showed a gradual elevation in cardiac NE content, which was already increased at 6 mo of age. Consistent with this finding, 6-mo-old VAChT KDHOM mice showed enhanced sympathetic activity and a greater abundance of tyrosine hydroxylase positive sympathetic nerves in the heart. VAChT mutants exhibited an increase in peak calcium transient, and mitochondrial oxidative stress in cardiomyocytes along with enhanced G protein-coupled receptor kinase 5 (GRK5) and nuclear factor of activated T-cells (NFAT) staining in the heart. These are known targets of adrenergic signaling in the cell. Moreover, vagotomized-mice displayed an increase in cardiac NE content confirming the data obtained in VAChT KDHOM mice. Establishing a causal relationship between acetylcholine and NE, VAChT KDHOM mice treated with pyridostigmine, a cholinesterase inhibitor, showed reduced cardiac NE content, rescuing the phenotype. Our findings unveil a yet unrecognized role of cholinergic signaling as a modulator of cardiac NE, providing novel insights into the mechanisms that drive autonomic imbalance.
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Colinérgicos , Norepinefrina , Adrenérgicos , Animales , Ratones , Miocitos Cardíacos , Proteínas de Transporte Vesicular de Acetilcolina/genéticaRESUMEN
Abstract Background: Mercury's deleterious effects are associated with increased cardiovascular risk. Objective: To determine whether chronic exposure to inorganic mercury increases the activity of angiotensin-converting enzyme and its relationship with oxidative stress in several organs and tissues. Methods: We studied male Wistar and spontaneously hypertensive rats (SHR) (3-month-old) exposed or not to HgCl2 for 30 days. At the end of treatment, we investigated the following: changes in body weight, hemodynamic parameters, angiotensin-converting enzyme (ACE) activity and oxidative stress in the heart, aorta, lung, brain and kidney in hypertensive compared to normotensive animals. A value of p < 0.05 was considered significant. Results: Chronic exposure to HgCl2 did not affect weight gain in either group. Systolic blood pressure, measured weekly, did not increase in Wistar rats but showed a small increase in SHR rats. We also observed increases in left ventricular end-diastolic pressure and ACE activity in the plasma and hearts of normotensive rats. In the SHR+Hg group, ACE activity increased in plasma but decreased in kidney, lung, heart, brain and aorta. Oxidative stress was assessed indirectly by malondialdehyde (MDA) production, which increased in Hg-treated rats in both plasma and heart. In the SHR+Hg group, MDA increased in heart and aorta and decreased in lungs and brain. Conclusion: These results suggest that chronic exposure to inorganic mercury aggravates hypertension and produces more expressive changes in ACE activity and oxidative stress in SHRs. Such exposure affects the cardiovascular system, representing a risk factor for the development of cardiovascular disorders in normotensive rats and worsening of pre-existing risks for hypertension.
Resumo Fundamento: Os efeitos deletérios do mercúrio estão associados ao risco cardiovascular aumentado. Objetivo: Determinar se a exposição crônica ao mercúrio inorgânico aumenta a atividade da enzima conversora de angiotensina e sua relação com o estresse oxidativo em vários órgãos e tecidos. Métodos: Estudamos ratos Wistar e ratos espontaneamente hipertensos (SHR) (3 meses de idade) expostos ou não a HgCl2 por 30 dias. Ao final do tratamento, investigamos: alterações de peso, parâmetros hemodinâmicos, atividade da enzima conversora de angiotensina (ECA) e estresse oxidativo no coração, aorta, pulmão, cérebro e rim de animais hipertensos comparados a animais normotensos. Um valor de p < 0,05 foi considerado significativo. Resultados: A exposição crônica ao HgCl2 não afetou o ganho de peso em nenhum dos grupos. A pressão arterial sistólica, medida semanalmente, não aumentou em ratos Wistar, mas mostrou um pequeno aumento nos ratos SHR. Também observamos aumentos na pressão diastólica final do ventrículo esquerdo e na atividade da ECA no plasma e no coração de ratos normotensos. No grupo SHR + Hg, a atividade da ECA aumentou no plasma, mas diminuiu no rim, pulmão, coração, cérebro e aorta. O estresse oxidativo foi avaliado indiretamente pela produção de MDA, que aumentou nos ratos tratados com Hg tanto no plasma quanto no coração. No grupo SHR + Hg, o MDA aumentou no coração e na aorta e diminuiu nos pulmões e no cérebro. Conclusão: Estes resultados sugerem que a exposição crônica ao mercúrio inorgânico agrava a hipertensão e produz mudanças mais expressivas na atividade da ECA e no estresse oxidativo em SHRs. Essa exposição afeta o sistema cardiovascular, representando um fator de risco para o desenvolvimento de distúrbios cardiovasculares em ratos normotensos e para piorar riscos pré-existentes para hipertensão.
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Animales , Masculino , Peptidil-Dipeptidasa A/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Hipertensión/metabolismo , Mercurio/toxicidad , Intoxicación por Mercurio/complicaciones , Aorta/enzimología , Ratas Endogámicas SHR , Valores de Referencia , Factores de Tiempo , Presión Sanguínea/efectos de los fármacos , Encéfalo/enzimología , Factores de Riesgo , Ratas Wistar , Peptidil-Dipeptidasa A/análisis , Corazón , Hipertensión/fisiopatología , Riñón/enzimología , Pulmón/enzimología , Malondialdehído/sangreRESUMEN
Testosterone is associated with an increased risk of coronary heart disease. This study evaluated cardiac remodeling 60 days after myocardial infarction (MI) in rats with testosterone deficiency. One week after castration, the animals underwent myocardial infarction. Rats were divided into four groups: orchidectomized (OCT); orchidectomized and infarcted (OCT+MI), MI and control (Sham). The myocyte cross-sectional area and the papillary muscle contractility were evaluated 8 weeks after MI. The coronary bed was perfused with Biodur E20 resin to evaluate the neovascularization after MI. Data were expressed as mean ± SEM followed by ANOVA. Castration reduced myocyte hypertrophy when compared to Sham and myocardial infarction alone as well as preserved the contraction force and activation time after myocardial infarction. After beta-adrenergic stimulation, activation and relaxation kinetics were less impaired in the OCT+MI group than in the MI group. Contraction force was preserved in the OCT+MI group after beta-adrenergic stimulation. Multiple scanning electronic microscope images were obtained to characterize changes in the coronary arteries. Capillary density index was increased in the MI and OCT+MI groups compared with control. The MI and OCT+MI groups were characterized by irregular vessel arrangements with distorted shape, abrupt changes in vessel direction, as well as abrupt changes in diameter after bifurcations when compared to Sham and OCT. The results indicated that testosterone deficiency attenuates adverse cardiac remodeling after MI. Novel findings in this study were that testosterone deficiency in rats, induced by castration, changes the later remodeling after MI, when compared with non castrated rats. The absence of this androgenous hormone seems to be benefic against pathological hypertrophy.
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Infarto del Miocardio/metabolismo , Infarto del Miocardio/patología , Testosterona/deficiencia , Remodelación Ventricular/fisiología , Animales , Vasos Coronarios/patología , Molde por Corrosión , Modelos Animales de Enfermedad , Masculino , Microscopía Electrónica de Rastreo , Contracción Miocárdica/fisiología , Miocitos Cardíacos/patología , Orquiectomía , Músculos Papilares/patología , Músculos Papilares/fisiopatología , Ratas , Ratas Wistar , Testosterona/fisiologíaRESUMEN
BACKGROUND: Mercury's deleterious effects are associated with increased cardiovascular risk. OBJECTIVE: To determine whether chronic exposure to inorganic mercury increases the activity of angiotensin-converting enzyme and its relationship with oxidative stress in several organs and tissues. METHODS: We studied male Wistar and spontaneously hypertensive rats (SHR) (3-month-old) exposed or not to HgCl2 for 30 days. At the end of treatment, we investigated the following: changes in body weight, hemodynamic parameters, angiotensin-converting enzyme (ACE) activity and oxidative stress in the heart, aorta, lung, brain and kidney in hypertensive compared to normotensive animals. A value of p < 0.05 was considered significant. RESULTS: Chronic exposure to HgCl2 did not affect weight gain in either group. Systolic blood pressure, measured weekly, did not increase in Wistar rats but showed a small increase in SHR rats. We also observed increases in left ventricular end-diastolic pressure and ACE activity in the plasma and hearts of normotensive rats. In the SHR+Hg group, ACE activity increased in plasma but decreased in kidney, lung, heart, brain and aorta. Oxidative stress was assessed indirectly by malondialdehyde (MDA) production, which increased in Hg-treated rats in both plasma and heart. In the SHR+Hg group, MDA increased in heart and aorta and decreased in lungs and brain. CONCLUSION: These results suggest that chronic exposure to inorganic mercury aggravates hypertension and produces more expressive changes in ACE activity and oxidative stress in SHRs. Such exposure affects the cardiovascular system, representing a risk factor for the development of cardiovascular disorders in normotensive rats and worsening of pre-existing risks for hypertension.
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Hipertensión/metabolismo , Intoxicación por Mercurio/complicaciones , Mercurio/toxicidad , Estrés Oxidativo/efectos de los fármacos , Peptidil-Dipeptidasa A/efectos de los fármacos , Animales , Aorta/enzimología , Presión Sanguínea/efectos de los fármacos , Encéfalo/enzimología , Corazón , Hipertensión/fisiopatología , Riñón/enzimología , Pulmón/enzimología , Masculino , Malondialdehído/sangre , Peptidil-Dipeptidasa A/análisis , Ratas Endogámicas SHR , Ratas Wistar , Valores de Referencia , Factores de Riesgo , Factores de TiempoRESUMEN
We previously demonstrated that the loss of female hormones induces cardiac and mitochondrial dysfunction in the female heart. Here, we show the impact of endurance training for twelve weeks, a nonpharmacological therapy against cardiovascular disease caused by ovariectomy and its contribution to cardiac contractility, mitochondrial quality control, bioenergetics and oxidative damage. We found that ovariectomy induced cardiac hypertrophy and dysfunction by decreasing SERCA2 and increasing phospholamban protein expression. Endurance training restored myocardial contractility, SERCA2 levels, increased calcium transient in ovariectomized rats but did not change phospholamban protein expression or cardiac hypertrophy. Additionally, ovariectomy decreased the amount of intermyofibrillar mitochondria and induced mitochondrial fragmentation that were accompanied by decreased levels of mitofusin 1, PGC-1α, NRF-1, total AMPK-α and mitochondrial Tfam. Endurance training prevented all these features except for mitofusin 1. Ovariectomy reduced O2 consumption, elevated O2.- release and increased Ca2+-induced mitochondrial permeability transition pore opening in both mitochondrial subpopulations. Ovariectomy also increased NOX-4 protein expression in the heart, reduced mitochondrial Mn-SOD, catalase protein expression and increased protein carbonylation in both mitochondrial subpopulations, which were prevented by endurance training. Taken together, our findings show that endurance training prevented cardiac contractile dysfunction and mitochondrial quality control in ovariectomized rats.
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Cardiomegalia/prevención & control , Entrenamiento Aeróbico , Mitocondrias Cardíacas/metabolismo , Miocardio/metabolismo , Condicionamiento Físico Animal , Animales , Cardiomegalia/etiología , Células Cultivadas , Metabolismo Energético , Femenino , Hormonas Esteroides Gonadales/metabolismo , Proteínas de Transporte de Membrana Mitocondrial/metabolismo , Poro de Transición de la Permeabilidad Mitocondrial , Contracción Miocárdica , Ovariectomía/efectos adversos , Estrés Oxidativo , Ratas , Ratas Wistar , Recuperación de la Función , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismoRESUMEN
The organotin compounds (OT) are used as fungicides, stabilizers in plastics, miticides, manufacturing and agricultural biocides, wood preservatives and antifouling agents. Tributyltin (TBT) is an OT that was first used for antifouling because it was the most effective agent to prevent undesirable accumulation of marine organisms on solid surfaces, such as ships' hulls or mechanical components, immersed in saltwater. TBT can be easily absorbed by mammals through ingestion, and its cytotoxic effects have become a major concern since their discovery in the 1970s. Recently, it has been demonstrated that TBT exposure is detrimental to the cardiovascular system. TBT is a membrane active substance and its action seems to depend on the OT lipophilicity. As a result, TBT crosses the cell membrane and damages the endothelium and the smooth muscle cells. TBT exposure induces vascular dysfunction, most likely due to endothelial dysfunction and morphological changes in the vascular wall. In an experimental rodent model, small doses of TBT (100 and 500 ng/kg/bw/day for 15 days) modified the vascular reactivity in aorta, mesenteric and coronary arteries followed by smooth muscle cell atrophy, increased collagen deposition and fibrin accumulation. TBT exposure increases oxidative stress by inducing vascular superoxide anion production derived from NADPH oxidase and decreases nitric oxide (NO) production as well as eNOS protein expression. The goal of this review is to summarize the current state of the art regarding the mechanisms involved in the vascular and endothelial dysfunction induced by TBT.
RESUMEN
Heavy metal exposure is associated with cardiovascular diseases such as myocardial infarction (MI). Vascular dysfunction is related to both the causes and the consequences of MI. We investigated whether chronic exposure to low doses of mercury chloride (HgCl2) worsens MI-induced endothelial dysfunction 7 days after MI. Male Wistar rats were divided into four groups: Control (vehicle), HgCl2 (4 weeks of exposure), surgically induced MI and combined HgCl2-MI. Morphological and hemodynamic measurements were used to characterize the MI model 7 days after the insult. Vascular reactivity was evaluated in aortic rings. Chronic HgCl2 exposure did not cause more heart injury than MI alone in terms of the morphological or hemodynamic parameters. Vascular reactivity increased in all groups, but the combination of HgCl2-MI increased the vasorelaxation induced by ACh compared with the HgCl2 and MI groups. Results showed reduced endothelial nitric oxide synthase (eNOS) protein expression in the MI group; increased iNOS activity in the HgCl2-MI group, although without enough magnitude to reverse the reduction in NO bioavailability; and increased phenylephrine response in the HgCl2-MI group due to an increase in ROS production, notably via xanthine oxidase (XO). Results suggest that the combination of 1 month pre-exposure of HgCl2 before MI changed the endothelial generation of oxidative stress induced by mercury exposure from NADPH oxidase pathway to XO (xanthine oxidase)-dependent ROS production.
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Aorta/efectos de los fármacos , Endotelio Vascular/efectos de los fármacos , Activadores de Enzimas/toxicidad , Cloruro de Mercurio/toxicidad , Infarto del Miocardio/enzimología , Vasoconstricción/efectos de los fármacos , Vasodilatación/efectos de los fármacos , Xantina Oxidasa/metabolismo , Animales , Aorta/enzimología , Aorta/fisiopatología , Modelos Animales de Enfermedad , Endotelio Vascular/enzimología , Endotelio Vascular/fisiopatología , Activación Enzimática , Masculino , Infarto del Miocardio/fisiopatología , Óxido Nítrico/metabolismo , Óxido Nítrico Sintasa de Tipo II/metabolismo , Óxido Nítrico Sintasa de Tipo III/metabolismo , Estrés Oxidativo/efectos de los fármacos , Ratas Wistar , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal/efectos de los fármacosRESUMEN
Organotin compounds, such as tributyltin (TBT), are environment contaminants that induce bioaccumulation and have potential toxic effects on marine species and mammals. TBT have been banned by the International Maritime Organization in 2003. However, the assessment of butyltin and metal contents in marine sediments has demonstrated high residual levels of TBT in some cases exceeding 7000 ng Sn g-1. The acceptable daily intake (ADI) level for TBT established by the World Health Organization is 0.5 µg/kg bw/day is based on genotoxicity, reproduction, teratogenicity, immunotoxicity, and mainly neurotoxicity. However, their effect on the cardiovascular system is not well understood. In this study, female rats were exposed to 0.5 µg/kg/day of TBT for 15 days with the goal of understanding the effect of TBT on vascular function. Female Wistar rats were treated daily by gavage and divided into control (n = 10) and TBT (n = 10) groups. The aortic rings were incubated with phenylephrine in both the presence and absence of endothelium. The phenylephrine concentration-response curves were generated by exposing endothelium-intact samples to NG-nitro-L-arginine methyl ester (L-NAME), apocynin, superoxide dismutase (SOD), catalase, tiron, and allopurinol. Acetylcholine (ACh) and sodium nitroprusside (SNP) were used to evaluate the relaxation response. Exposure to TBT reduced serum 17ß-estradiol E2 levels and increased vascular reactivity. After incubation with L-NAME, the vascular reactivity to phenylephrine was significantly higher. Apocynin, SOD, catalase, and tiron decreased the vascular reactivity to phenylephrine to a significantly greater extent in TBT-treated rats than in the control rat. The relaxation induced by ACh and SNP was significantly reduced in TBT rats. Exposure to TBT induced aortic wall atrophy and increased superoxide anion production and collagen deposition. These results provide evidence that exposing rats to the current ADI for TBT (0.5 µg/kg) for 15 days induced vascular dysfunction due to oxidative stress and morphological damage and should be considered an important cardiovascular risk factor.
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Aorta/efectos de los fármacos , Endotelio Vascular/efectos de los fármacos , Contaminantes Ambientales/efectos adversos , Estrés Oxidativo/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Compuestos de Trialquiltina/efectos adversos , Animales , Femenino , Distribución Aleatoria , Ratas , Ratas WistarRESUMEN
BACKGROUND: Physical exercise is an important tool for the improvement of endothelial function. OBJECTIVE: To assess the effects of acute dynamic resistance exercise on the endothelial function of spontaneously hypertensive rats (SHR). METHODS: Ten minutes after exercise, the aorta was removed to evaluate the expression of endothelial nitric oxide synthase (eNOS), phosphorylated endothelial nitric oxide synthase (p-eNOS1177) and inducible nitric oxide synthase (iNOS) and to generate concentration-response curves to acetylcholine (ACh) and to phenylephrine (PHE). The PHE protocol was also performed with damaged endothelium and before and after NG-nitro-L-arginine methyl ester (L-NAME) and indomethacin administration. The maximal response (Emax) and the sensitivity (EC50) to these drugs were evaluated. RESULTS: ACh-induced relaxation increased in the aortic rings of exercised (Ex) rats (Emax= -80 ± 4.6%, p < 0.05) when compared to those of controls (Ct) (Emax = -50 ± 6.8%). The Emax to PHE was decreased following exercise conditions (95 ± 7.9%, p < 0.05) when compared to control conditions (120 ± 4.2%). This response was abolished after L-NAME administration or endothelial damage. In the presence of indomethacin, the aortic rings' reactivity to PHE was decreased in both groups (EC50= Ex -5.9 ± 0.14 vs. Ct -6.6 ± 0.33 log µM, p < 0.05 / Emax = Ex 9.5 ± 2.9 vs. Ct 17 ± 6.2%, p < 0.05). Exercise did not alter the expression of eNOS and iNOS, but increased the level of p-eNOS. CONCLUSION: A single resistance exercise session improves endothelial function in hypertensive rats. This response seems to be mediated by increased NO production through eNOS activation.
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Aorta Torácica/metabolismo , Aorta Torácica/fisiopatología , Endotelio Vascular/metabolismo , Endotelio Vascular/fisiopatología , Condicionamiento Físico Animal/fisiología , Acetilcolina , Animales , Aorta Torácica/química , Western Blotting , Endotelio Vascular/química , Prueba de Esfuerzo , Hipertensión/metabolismo , Hipertensión/fisiopatología , Masculino , NG-Nitroarginina Metil Éster , Óxido Nítrico/análisis , Óxido Nítrico/metabolismo , Óxido Nítrico Sintasa de Tipo II/metabolismo , Óxido Nítrico Sintasa de Tipo III/análisis , Óxido Nítrico Sintasa de Tipo III/metabolismo , Fenilefrina , Fosforilación/fisiología , Prostaglandinas/metabolismo , Distribución Aleatoria , Ratas Endogámicas SHR , Valores de Referencia , Entrenamiento de Fuerza , Factores de Tiempo , Vasoconstricción/fisiologíaRESUMEN
Abstract Background: Physical exercise is an important tool for the improvement of endothelial function. Objective: To assess the effects of acute dynamic resistance exercise on the endothelial function of spontaneously hypertensive rats (SHR). Methods: Ten minutes after exercise, the aorta was removed to evaluate the expression of endothelial nitric oxide synthase (eNOS), phosphorylated endothelial nitric oxide synthase (p-eNOS1177) and inducible nitric oxide synthase (iNOS) and to generate concentration-response curves to acetylcholine (ACh) and to phenylephrine (PHE). The PHE protocol was also performed with damaged endothelium and before and after NG-nitro-L-arginine methyl ester (L-NAME) and indomethacin administration. The maximal response (Emax) and the sensitivity (EC50) to these drugs were evaluated. Results: ACh-induced relaxation increased in the aortic rings of exercised (Ex) rats (Emax= -80 ± 4.6%, p < 0.05) when compared to those of controls (Ct) (Emax = -50 ± 6.8%). The Emax to PHE was decreased following exercise conditions (95 ± 7.9%, p < 0.05) when compared to control conditions (120 ± 4.2%). This response was abolished after L-NAME administration or endothelial damage. In the presence of indomethacin, the aortic rings' reactivity to PHE was decreased in both groups (EC50= Ex -5.9 ± 0.14 vs. Ct -6.6 ± 0.33 log µM, p < 0.05 / Emax = Ex 9.5 ± 2.9 vs. Ct 17 ± 6.2%, p < 0.05). Exercise did not alter the expression of eNOS and iNOS, but increased the level of p-eNOS. Conclusion: A single resistance exercise session improves endothelial function in hypertensive rats. This response seems to be mediated by increased NO production through eNOS activation.
Resumo Fundamento: O exercício físico é uma importante ferramenta para o aprimoramento da função endotelial. Objetivo: Avaliar os efeitos do exercício dinâmico resistido agudo na função endotelial de ratos espontaneamente hipertensos (SHR). Métodos: Após 10 minutos de exercício, a aorta foi removida para avaliação da expressão de óxido nítrico sintase endotelial (eNOS), óxido nítrico sintase endotelial fosforilada (p-eNOS1177) e óxido nítrico sintase endotelial induzível (iNOS), e para a construção de curvas concentração-resposta de acetilcolina (ACT) e fenilefrina (FEN). O protocolo FEN foi também realizado com lesão endotelial e antes e depois da administração de N-nitro-L-arginina metil éster (L-NAME) e indometacina. A resposta máxima (Emax) e a sensibilidade (EC50) a esses fármacos foram avaliadas. Resultados: Houve aumento do relaxamento induzido por ACT nos anéis aórticos dos ratos exercitados (Ex) (Emax = -80 ± 4,6%; p < 0,05) quando comparado àquele dos controles (Ct) (Emax = -50 ± 6,8%). A Emax à FEN diminuiu após exercício (95 ± 7,9%; p < 0,05) quando comparada àquela dos controles (120 ± 4,2%). Tal resposta foi abolida após administração de L-NAME ou lesão endotelial. Na presença de indometacina, a reatividade dos anéis aórticos à FEN diminuiu nos dois grupos (EC50= Ex -5,9 ± 0,14 vs. Ct -6,6 ± 0,33 log µM; p < 0,05/ Emax = Ex 9,5 ± 2,9 vs. Ct 17 ± 6,2%; p < 0,05). O exercício não alterou a expressão de eNOS e de iNOS, mas aumentou o nível de p-eNOS. Conclusão: Uma única sessão de exercício resistido melhora a função endotelial em ratos hipertensos. Essa resposta parece ser mediada por elevação da produção de NO através de ativação de eNOS.
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Animales , Masculino , Aorta Torácica/fisiopatología , Aorta Torácica/metabolismo , Condicionamiento Físico Animal/fisiología , Endotelio Vascular/fisiopatología , Endotelio Vascular/metabolismo , Aorta Torácica/química , Fenilefrina , Fosforilación/fisiología , Factores de Tiempo , Vasoconstricción/fisiología , Endotelio Vascular/química , Acetilcolina , Prostaglandinas/metabolismo , Western Blotting , NG-Nitroarginina Metil Éster , Óxido Nítrico Sintasa de Tipo II/metabolismo , Óxido Nítrico Sintasa de Tipo III/análisis , Óxido Nítrico Sintasa de Tipo III/metabolismo , Prueba de Esfuerzo , Hipertensión/fisiopatología , Hipertensión/metabolismo , Óxido Nítrico/análisis , Óxido Nítrico/metabolismoRESUMEN
The renin-angiotensin-system is an important component of cardiovascular control and is up-regulated under various conditions, including hypertension and menopause. The aim of this study was to evaluate the effects of swimming training and estrogen therapy (ET) on angiotensin-II (ANG II)-induced vasoconstriction and angiotensin-(1-7) [ANG-(1-7)]-induced vasorelaxation in aortic rings from ovariectomized spontaneously hypertensive rats. Animals were divided into Sham (SH), Ovariectomized (OVX), Ovariectomized treated with E2 (OE2), Ovariectomized plus swimming (OSW) and Ovariectomized treated with E2 plus swimming (OE2+SW) groups. ET entailed the administration of 5µg of 17ß-Estradiol three times per week. Swimming was undertaken for sixty minutes each day, five times per week. Both, training and ET were initiated seven days following ovariectomy. Forty-eight hours after the last treatment or training session, the animals' systolic blood pressures were measured, and blood samples were collected to measure plasma ANG II and ANG-(1-7) levels via radioimmunoassay. In aortic rings, the vascular reactivity to ANG II and ANG-(1-7) was assessed. Expression of ANG-(1-7) in aortic wall was analyzed by immunohistochemistry. The results showed that both exercise and ET increased plasma ANG II levels despite attenuating systolic blood pressure. Ovariectomy increased constrictor responses to ANG II and decreased dilatory responses to ANG-(1-7), which were reversed by swimming independently of ET. Moreover, it was observed an apparent increase in ANG-(1-7) content in the aorta of the groups subjected to training and ET. Exercise training may play a cardioprotective role independently of ET and may be an alternative to ET in hypertensive postmenopausal women.
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Aorta/metabolismo , Terapia por Ejercicio , Hipertensión/terapia , Condicionamiento Físico Animal , Angiotensina I/sangre , Angiotensina II/sangre , Animales , Aorta/patología , Estradiol/administración & dosificación , Estrógenos/metabolismo , Estrógenos/uso terapéutico , Humanos , Hipertensión/sangre , Hipertensión/fisiopatología , Ovariectomía , Fragmentos de Péptidos/sangre , Ratas , Ratas Endogámicas SHR , Sistema Renina-Angiotensina/genéticaRESUMEN
Spatially distinct mitochondrial subpopulation may mediate myocardial pathology through permeability transition pore opening (MPTP). The goal of this study was to assess sex differences on the two spatially distinct mitochondrial subpopulations: subsarcolemmal mitochondria (SSM) and intermyofibrillar mitochondria (IFM) based on morphology, membrane potential, mitochondrial function, oxidative phosphorylation, and MPTP. Aged matched Wistar rats were used to study SSM and IFM. Mitochondrial size was larger in SSM than in IFM in both genders. However, SSM internal complexity, yield, and membrane potential were higher in male than in female. The maximal rate of mitochondrial respiration, states 3 and 4, using glutamate + malate as substrate, were higher in IFM and SSM in the male group compared to female. The respiratory control ratio (RCR-state3/state 4), was not different in both SSM and IFM with glutamate + malate. The ADP:O ratio was found higher in IFM and SSM from female compared to males. When pyruvate was used, state 3 was found unchanged in both IFM and SSM, state 4 was also greater in male IFM compared to female. The RCR increased in the SSM while IFM remained the same. State 4 was higher in male SSM while in the IFM remained the same. The IFM presented a higher Ca(2+) retention capacity compared with SSM, however, there was a greater sensitivity to Ca(2+)-induced MPTP in SSM and IFM in the male group compared to female. In conclusion, our data show that spatially distinct mitochondrial subpopulations have sex-based differences in oxidative phosphorylation, morphology, and calcium retention capacity.
Asunto(s)
Adenosina Difosfato/metabolismo , Calcio/metabolismo , Mitocondrias Cardíacas/metabolismo , Proteínas de Transporte de Membrana Mitocondrial/metabolismo , Fosforilación Oxidativa , Caracteres Sexuales , Animales , Femenino , Masculino , Poro de Transición de la Permeabilidad Mitocondrial , Ratas , Ratas WistarRESUMEN
BACKGROUND: Several studies show that the consumption of vegetable oils, such as soybean oil, rich in polyunsaturated fatty acids (PUFAs) has beneficial health effects by preventing or reducing the risk factors of cardiovascular diseases. While the demonstration of beneficial effects of the consumption of unsaturated fatty acids on the cardiovascular system has been proven in a macroscopic level, the molecular/cellular mechanisms responsible for this phenomenon are poorly understood. METHODS: In this work, a comparative proteomic approach, two-dimensional gel electrophoresis (2-DE) coupled to mass spectrometry (MALDI-TOF/TOF), was applied to investigate proteome differences in the left ventricle (LV) of rats that received 0.1 mL of soybean oil intramuscularly for 15 days (treated group-TR) and rats that had not (control group-CT). RESULTS: Soybean oil treatment improved left ventricular function, TR animals presented lower value of LVEDP and significantly changed LV proteome. The protein profile of VE revealed differences in the expression of 60 protein spots (p<0.05) between the experimental groups (CT and TR), 14 of those were identified by MS and MS/MS, and 12 of the 14 being non-redundant proteins. Robust changes were detected in proteins involved in cellular structure and antioxidant system and muscular contraction. CONCLUSIONS: The TR group presented an increase in the intensity of proteins involved in muscle contraction (myosin light chain-3 (3-MCL), creatine kinase M (CKM)) and thireodoxin, an antioxidant enzyme. Low intensity cytoskeletal protein, desmin, was also detected in TR animals. The results suggest that soybean oil induces changes in the levels of heart proteins which may partially account for the underlying mechanisms involved in the benefits provided by oils rich in polyunsaturated fatty acids.
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Ventrículos Cardíacos/efectos de los fármacos , Proteómica , Aceite de Soja/farmacología , Animales , Electroforesis en Gel Bidimensional , Ventrículos Cardíacos/química , Inyecciones Intramusculares , Masculino , Proteínas/análisis , Proteómica/métodos , Ratas , Ratas Wistar , Aceite de Soja/administración & dosificación , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Función Ventricular Izquierda/efectos de los fármacosRESUMEN
AIMS: Right ventricular (RV) function is considered an independent predictor of mortality and development of heart failure (HF) in patients with left ventricle dysfunction following myocardial infarction (MI). The functional and molecular mechanisms that may explain the RV dysfunction are still poorly understood. Our study was conducted to investigate RV contractility and the myocardium protein involved in the calcium handling following MI in rats. MAIN METHODS: MI was surgically induced in male Wistar rats to create transmural infarctions involving 40-60% of the left ventricle surface. Infarcted rats were divided into two groups: those that presented classical signs of congestive heart failure (HF group) and those that did not (INF group), and compared to control animals (Sham). RV contractility was studied using isometric contraction in isolated strips and isovolumetric pressure in isolated heart. KEY FINDINGS: Inotropic responses in RV strips were preserved in the INF group but were reduced in the HF group (3.75 mM Ca(2+) treatment: Sham = 163 ± 18; INF = 148 ± 19; HF = 68 ± 11 g/g*; *p < 0.05; 5 × 10(-5) M isoproterenol: Sham = 151 ± 15, INF = 134 ± 17, HF = 52 ± 7 g/g*; *p < 0.05). An increase in SERCA-2a protein expression in the RV was observed in the INF group but not in the HF group, which could explain the preserved inotropic response in these animals. SIGNIFICANCE: Increased SERCA-2a protein expression may play a role in the preservation of RV function post-MI. Therefore, therapeutic strategies that attempt to increase SERCA protein expression levels may be useful for the treatment of HF.
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Insuficiencia Cardíaca/fisiopatología , Infarto del Miocardio/fisiopatología , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/genética , Disfunción Ventricular Izquierda/fisiopatología , Función Ventricular Derecha/fisiología , Animales , Modelos Animales de Enfermedad , Regulación de la Expresión Génica , Contracción Isométrica/fisiología , Isoproterenol/farmacología , Masculino , Ratas , Ratas WistarRESUMEN
BACKGROUND: Ouabain occurs in nanomolar concentrations in myocardial infarction and heart failure (HF). However, the effects of ouabain in vascular function in HF conditions were not investigated yet. Therefore, we analyzed the effects of acute administration of 3 nM ouabain in isolated aortic rings from rats with HF 4 weeks after myocardial infarction. METHODS AND RESULTS: Rats were submitted to sham operation or coronary artery occlusion. In HF rats, left ventricular positive and negative derivatives of intraventricular pressure reduced and left ventricular end diastolic pressure increased. Phenylephrine responses increased in HF rings when compared with controls. Ouabain incubation for 45 minutes reduced phenylephrine-induced contraction in both groups. Endothelial removal increased more phenylephrine response in ouabain-treated rings of sham rats. Ouabain potentiated the effect of L-NAME in both groups but more in sham rats. Wortmannin increased the phenylephrine response only in HF rings. The effect of tetraethylammonium was potentiated by ouabain only in HF rings. Ouabain increased phenylephrine-stimulated nitric oxide production in rings from both groups but increased the activation of Akt only in vessels from HF rats. CONCLUSIONS: Results demonstrate that low ouabain concentration can decrease vascular reactivity of aortic rings from HF rats. Ouabain was able to increase nitric oxide production in HF rats by triggering a signal transduction PI3K/Akt-dependent pathway and increasing an endothelium-hyperpolarizing factor release.
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Insuficiencia Cardíaca/fisiopatología , Infarto del Miocardio/fisiopatología , Óxido Nítrico/metabolismo , Ouabaína/farmacología , Animales , Aorta Torácica/metabolismo , Masculino , NG-Nitroarginina Metil Éster/farmacología , Ouabaína/administración & dosificación , Ouabaína/metabolismo , Fenilefrina/farmacología , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Ratas , Ratas WistarRESUMEN
Gender associated differences in vascular reactivity regulation might contribute to the low incidence of cardiovascular disease in women. Cardiovascular protection is suggested to depend on female sex hormones' effects on endothelial function and vascular tone regulation. We tested the hypothesis that potassium (K+) channels and Na+K+-ATPase may be involved in the gender-based vascular reactivity differences. Aortic rings from female and male rats were used to examine the involvement of K+ channels and Na+K+-ATPase in vascular reactivity. Acetylcholine (ACh)-induced relaxation was analyzed in the presence of L-NAME (100 µM) and the following K+ channels blockers: tetraethylammonium (TEA, 2 mM), 4-aminopyridine (4-AP, 5 mM), iberiotoxin (IbTX, 30 nM), apamin (0.5 µM) and charybdotoxin (ChTX, 0.1 µM). The ACh-induced relaxation sensitivity was greater in the female group. After incubation with 4-AP the ACh-dependent relaxation was reduced in both groups. However, the dAUC was greater in males, suggesting that the voltage-dependent K+ channel (Kv) participates more in males. Inhibition of the three types of Ca2+-activated K+ channels induced a greater reduction in Rmax in females than in males. The functional activity of the Na+K+-ATPase was evaluated by KCl-induced relaxation after L-NAME and OUA incubation. OUA reduced K+-induced relaxation in female and male groups, however, it was greater in males, suggesting a greater Na+K+-ATPase functional activity. L-NAME reduced K+-induced relaxation only in the female group, suggesting that nitric oxide (NO) participates more in their functional Na+K+-ATPase activity. These results suggest that the K+ channels involved in the gender-based vascular relaxation differences are the large conductance Ca2+-activated K+ channels (BKCa) in females and Kv in males and in the K+-induced relaxation and the Na+K+-ATPase vascular functional activity is greater in males.
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Canales de Potasio/metabolismo , ATPasa Intercambiadora de Sodio-Potasio/metabolismo , 4-Aminopiridina/farmacología , Animales , Apamina/farmacología , Caribdotoxina/farmacología , Femenino , Masculino , NG-Nitroarginina Metil Éster/farmacología , Bloqueadores de los Canales de Potasio/farmacología , Ratas , Factores Sexuales , Tetraetilamonio/farmacología , Vasodilatación/efectos de los fármacosRESUMEN
We investigated the cardiovascular effects of lead exposure, emphasising its direct action on myocardial contractility. Male Wistar rats were sorted randomly into two groups: control (Ct) and treatment with 100 ppm of lead (Pb) in the drinking water. Blood pressure (BP) was measured weekly. At the end of the treatment period, the animals were anaesthetised and haemodynamic parameters and contractility of the left ventricular papillary muscles were recorded. Blood and tissue samples were properly stored for further biochemical investigations. Statistical analyses were considered to be significant at p<0.05. The lead concentrations in the blood reached approximately 13 µg/dL, while the bone was the site of the highest deposition of this metal. BP in the Pb-treated group was higher from the first week of lead exposure and remained at the same level over the next four weeks. Haemodynamic evaluations revealed increases in systolic (Ct: 96 ± 3.79 vs. Pb: 116 ± 1.37 mmHg) and diastolic blood pressure (Ct: 60 ± 2.93 vs. Pb: 70 ± 3.38 mmHg), left ventricular systolic pressure (Ct: 104 ± 5.85 vs. Pb: 120 ± 2.51 mmHg) and heart rate (Ct: 307 ± 10 vs. Pb: 348 ± 16 bpm). Lead treatment did not alter the force and time derivatives of the force of left ventricular papillary muscles that were contracting isometrically. However, our results are suggestive of changes in the kinetics of calcium (Ca++) in cardiomyocytes increased transarcolemmal Ca++ influx, low Ca++ uptake by the sarcoplasmic reticulum and high extrusion by the sarcolemma. Altogether, these results show that despite the increased Ca++ influx that was induced by lead exposure, the myocytes had regulatory mechanisms that prevented increases in force, as evidenced in vivo by the increased systolic ventricular pressure.
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Presión Sanguínea/efectos de los fármacos , Calcio/metabolismo , Plomo/toxicidad , Animales , Transporte Biológico/efectos de los fármacos , Masculino , Contracción Miocárdica/efectos de los fármacos , Ratas , Ratas Wistar , Retículo Sarcoplasmático/efectos de los fármacos , Retículo Sarcoplasmático/metabolismoRESUMEN
Right ventricle systolic dysfunction is a major risk factor for death and heart failure after myocardial infarction (MI). Heavy metal exposure has been associated with the development of several cardiovascular diseases, such as MI. The aim of this study was to investigate whether chronic exposure to low doses of mercury chloride (HgCl2) enhances the functional deterioration of right ventricle strips after MI. Male Wistar rats were divided into four groups: Control (vehicle); HgCl2 (exposure during 4 weeks- 1st dose 4.6 µg/kg, subsequent dose 0.07 µg/kg/day, i.m. to cover daily loss); MI surgery induced and HgCl2-MI groups. One week after MI, the morphological and hemodynamic measurements and isometric tension of right ventricle strips were investigated. The chronic HgCl2 exposure did not worsen the injury compared with MI alone in the morphological or hemodynamic parameters evaluated. At basal conditions, despite similar maximum isometric force at L-max, relaxation time was increased in the MI group but unaffected in the HgCl2-MI compared to the Control group. Impairment of the sarcoplasmic reticulum (SR) function and reduction in the sarcolemmal calcium influx were observed in MI group associated with SERCA2a reduction and increased PLB protein expression. Induction of MI in chronic HgCl2 exposed rats did not cause any alteration in the developed force at L-max, lusitropic function or -dF/dt except for a tendency of a reduction SR function. These findings could be partially explained by the normalization in the sarcolemmal calcium influx and the increase in NCX protein expression observed only in this group. These results suggest that chronic exposure to low doses of HgCl2 prevents the impaired SR function and the reduced sarcolemmal calcium influx observed in MI likely by acting on NCX, PLB and SERCA2a protein expression.