RESUMO
In skeletal muscle (SM), inward Ca2+-currents have no apparent role in excitation-contraction coupling (e-c coupling), however the Ca2+-channel blocker can affect twitch and tetanic muscle in mammalian SM. Experiments were conducted to study how diltiazem (DLZ) facilitates e-c coupling and inhibits contraction. 1) In complete Extensor Digitorum Longus (EDL) muscle and single intact fibres, 0.03 mM DLZ causes twitch potentiation and decreases force during tetanic activity, with increased fatigue. 2) In split open fibres isolated from EDL fibres, DLZ inhibits sarcoplasmic reticulum (SR) Ca2+-loading in a dose-dependent manner and has a potentiating effect on caffeine-induced SR Ca2+-release. 3) In isolated light SR (LSR) vesicles, SERCA1 hydrolytic activity is not affected by DLZ up to 0.2 mM. However, ATP-dependent Ca2+-uptake was inhibited in a dose-dependent manner at a concentration where e-c coupling is changed. 4) The passive Ca2+-efflux from LSR was reduced by half with 0.03 mM diltiazem, indicating that SR leaking does not account for the decreased Ca2+-uptake. 5) The denaturation profile of the SERCA Ca2+-binding domain has lower thermal stability in the presence of DLZ in a concentration-dependent manner, having no effect on the nucleotide-binding domain. We conclude that the effect of DLZ on SM is exerted by crossing the sarcolemma and interacting directly with the SERCA Ca2+-binding domain, affecting SR Ca2+-loading during relaxation, which has a consequence on SM contractility. Diltiazem effect on SM could be utilized as a tool to understand SM e-c coupling and muscle fatigue.
Assuntos
Diltiazem , Músculo Esquelético , Animais , Diltiazem/farmacologia , Retículo Sarcoplasmático , Fadiga Muscular , Cafeína/farmacologia , Mamíferos , Contração Muscular , Cálcio/farmacologiaRESUMO
Flavonoids are a group of secondary metabolites derived from plant-based foods, and they offer many health benefits in different stages of several diseases. This review will focus on their effects on ion channels expressed in vascular smooth muscle during atherosclerosis. Since ion channels can be regulated by redox potential, it is expected that during the onset of oxidative stress-related diseases, ion channels present changes in their conductive activity, impacting the progression of the disease. A typical oxidative stress-related condition is atherosclerosis, which involves the dysfunction of vascular smooth muscle. We aim to present the state of the art on how redox potential affects vascular smooth muscle ion channel function and summarize if the benefits observed in this disease by using flavonoids involve restoring the ion channel activity.
Assuntos
Aterosclerose/tratamento farmacológico , Flavonoides/farmacologia , Músculo Liso Vascular/efeitos dos fármacos , Animais , Aterosclerose/metabolismo , Progressão da Doença , Humanos , Canais Iônicos/metabolismo , Músculo Liso Vascular/metabolismo , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/metabolismo , Oxirredução/efeitos dos fármacosRESUMO
Chronic kidney disease (CKD) represents a serious concern for the Mexican population since the main predisposing diseases (diabetes, hypertension, etc.) have a high prevalence in the country. The development of frequent comorbidities during CKD such as anemia, metabolic disorders, and hyperphosphatemia increases the costs, symptoms, and death risks of the patients. Hyperphosphatemia is likely the only CKD comorbidity in which pharmaceutical options are restricted to phosphate binders and where nutritional management seems to play an important role for the improvement of biochemical and clinical parameters. Nutritional interventions aiming to control serum phosphate levels need to be based on food tables, which should be specifically elaborated for the cultural context of each population. Until now, there are no available food charts compiling a high amount of Mexican foods and describing phosphorus content as well as the phosphate to protein ratio for nutritional management of hyperphosphatemia in CKD. In this work, we elaborate a highly complete food chart as a reference for Mexican clinicians and include charts of additives and drug phosphate contents to consider extra sources of inorganic phosphate intake. We aim to provide an easy guideline to contribute to the implementation of more nutritional interventions focusing on this population in the country.
Assuntos
Hiperfosfatemia/dietoterapia , Política Nutricional , Insuficiência Renal Crônica/complicações , Dieta , Aditivos Alimentares/administração & dosagem , Humanos , Hiperfosfatemia/etiologia , México , Fósforo na Dieta/administração & dosagem , Fósforo na Dieta/farmacocinética , Insuficiência Renal Crônica/dietoterapia , Insuficiência Renal Crônica/tratamento farmacológicoRESUMO
Matrix metalloproteinases (MMP) are key players in the remodelling of the extracellular matrix under physiological and pathological conditions. Thermodynamic parameters of human recombinant metalloproteinases of the active (rMMP2, 3, 7, 8 and 9) and latent (rPro-MMP2, 3 and 9) forms were obtained by differential scanning calorimetry (DSC). Temperature by itself does not result in autocatalysis of recombinant MMP. The transitions observed by DSC correspond to structural domains of the monomeric protein. In this study, we show the domain organization of these proteins, where the thermal transition (Tm) of the main component is observed at 71.3 °C (ProMMP-2); 74.8 °C (ProMMP-8); 80.0 °C (ProMMP-3); 92.6 °C (ProMMP-9) and 98.3 °C (ProMMP-7). For MMP-3, this main Tm is related to the catalytic domain (CD). The isolated recombinant CD of MMP-3 unfolds as a single transition at Tm 83.4 °C, matching the more stable domain observed in the full-length active form of rMMP-3. The denaturation profile of rProMMP-3 shows the main transition at Tm 80 °C, a less stable domain before the propeptide domain (PD) cleavage. Our results indicate that the structural stability of MMP and particularly their CD are not substantially altered after cleavage of the PD. We propose that the thermodynamic parameters obtained by DSC are relevant for the functional study of MMP, particularly to reveal their contribution in complex biological samples in health and disease.
RESUMO
Inflammation has been recently acknowledged as a key participant in the physiopathology of oncogenesis and tumor progression. The inflammatory cytokine IL-1ß has been reported to induce the expression of markers associated with malignancy in breast cancerous cells through Epithelial-Mesenchymal Transition (EMT). Aggressive breast cancer tumors classified as Triple Negative do not respond to hormonal treatment because they lack three crucial receptors, one of which is the estrogen receptor alpha (ERα). Expression of ERα is then considered a good prognostic marker for tamoxifen treatment of this type of cancer, as the binding of this drug to the receptor blocks the transcriptional activity of the latter. Although it has been suggested that inflammatory cytokines in the tumor microenvironment could regulate ERα expression, the mechanism(s) involved in this process have not yet been established. We show here that, in a cell model of breast cancer cells (6D cells), in which the inflammatory cytokine IL-1ß induces EMT by activation of the IL-1ß/IL-1RI/ß-catenin pathway, the up regulation of TWIST1 leads to methylation of the ESR1 gene promoter. This epigenetic modification produced significant decrease of the ERα receptor levels and increased resistance to tamoxifen. The direct participation of IL-1ß in these processes was validated by blockage of the cytokine-induced signaling pathway by wortmannin inactivation of the effectors PI3K/AKT. These results support our previous reports that have suggested direct participation of the inflammatory cytokine IL-1ß in the transition to malignancy of breast cancer cells.
Assuntos
Antineoplásicos Hormonais/farmacologia , Neoplasias da Mama/tratamento farmacológico , Metilação de DNA , Resistencia a Medicamentos Antineoplásicos , Receptor alfa de Estrogênio/genética , Interleucina-1beta/imunologia , Tamoxifeno/farmacologia , Mama/efeitos dos fármacos , Mama/imunologia , Mama/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/imunologia , Metilação de DNA/efeitos dos fármacos , Receptor alfa de Estrogênio/imunologia , Feminino , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Células MCF-7 , Proteínas Nucleares/genética , Proteínas Nucleares/imunologia , Fosfatidilinositol 3-Quinases/imunologia , Regiões Promotoras Genéticas/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/imunologia , Proteína 1 Relacionada a Twist/genética , Proteína 1 Relacionada a Twist/imunologiaRESUMO
BACKGROUND/AIMS: [corrected] Skeletal muscle (SM) constitutes more than 40% of the body weight in adulthood. Transports dietary glucose mainly through the insulin-dependent glucose transporter (Glut-4) located in the Transverse tubule membrane system (TT). The TT development ends shortly after birth. The TT membrane hosts the proteins involved in excitation-contraction coupling and glucose uptake. Glycaemic regulation through movement is a key function of fully developed skeletal muscle. In this study, we aimed to characterize the effect of gestational undernourishment (GUN) in rats GLUT-4 expression and on the protein/lipid content of the TT membranes. We also examined the effect of GUN on the mechanical properties of muscles as an indication of the metabolic condition of the SM at birth. METHODS: Isolated TT membrane from SM of GUN rats were used to study lipid/protein content and protein stability by differential scanning calorimetry. The effect of GUN on the SM mechanical properties was determined in isolated Extensor Digitorum Longus (EDL) muscle. RESULTS: We demonstrate that compared to control, GUN in the new-born produces; i) decreases body weight; ii) diminution in SM mass; iii) decreases the formation of TT membranes; iv) expresses TT membrane proteins with higher thermal stability. The TT membrane expression of GLUT-4 in GUN offspring was twice that of controls. The isolated EDL of GUN offspring was 20% stronger as measured by contractile force and more resistant to fatigue relative to controls. CONCLUSION: These results provide the first evidence of adaptive changes of the SM in new-borns exposed to severe gestational food restriction. The effects of GUN on muscle at birth are the first step toward detrimental SM metabolic function, contributing to the physiopathology of metabolic diseases in adulthood.
Assuntos
Transtornos da Nutrição Fetal/metabolismo , Músculo Esquelético/metabolismo , Animais , Animais Recém-Nascidos , Feminino , Transportador de Glucose Tipo 4/metabolismo , Contração Muscular/fisiologia , Proteínas Musculares/metabolismo , Gravidez , Sarcolema/metabolismo , Retículo Sarcoplasmático/metabolismoRESUMO
A small number of patients with carcinoma of the gallbladder can present with a variety of paraneoplastic syndromes, including the Cushing syndrome, hypercalcemia, acanthosis nigricans, bullous pemphigoid, dermatomyositis, and the Leser-Trélat sign. We report on what appears to be the first case of a patient, a 48-year-old woman, with anti-Hu paraneoplastic sensory neuropathy and small cell carcinoma of the gallbladder. The patient's neurologic symptoms preceded the diagnosis of small cell carcinoma by 11 months. These symptoms improved after surgical removal of the tumor and chemotherapy. The small cell carcinoma was relatively small and was not associated with gallstones. In spite of the small size of the tumor, it metastasized to a celiac lymph node and probably to the liver. Anti-Hu paraneoplastic sensory neuropathy should be added to the list of paraneoplastic syndromes associated with small cell carcinoma of the gallbladder.