RESUMO
We investigated how oxidative stress (OS) alters Ca2+ handling in ventricular myocytes in early metabolic syndrome (MetS) in sucrose-fed rats. The effects of N-acetyl cysteine (NAC) or dl-Dithiothreitol (DTT) on systolic Ca2+ transients (SCaTs), diastolic Ca2+ sparks (CaS) and Ca2+ waves (CaW), recorded by confocal techniques, and L-type Ca2+ current (ICa), assessed by whole-cell patch clamp, were evaluated in MetS and Control cells. MetS myocytes exhibited decreased SCaTs and CaS frequency but unaffected CaW propagation. In Control cells, NAC/DTT reduced RyR2/SERCA2a activity blunting SCaTs, CaS frequency and CaW propagation, suggesting that basal ROS optimised Ca2+ signalling by maintaining RyR2/SERCA2a function and that these proteins facilitate CaW propagation. Conversely, NAC/DTT in MetS recovered RyR2/SERCA2a function, improving SCaTs and CaS frequency, but unexpectedly decreasing CaW propagation. We hypothesised that OS decreases RyR2/SERCA2a activity at early MetS, and while decreased SERCA2a favours CaW propagation, diminished RyR2 restrains it.
Assuntos
Síndrome Metabólica , Canal de Liberação de Cálcio do Receptor de Rianodina , Ratos , Animais , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/farmacologia , Síndrome Metabólica/metabolismo , Miócitos Cardíacos , Estresse OxidativoRESUMO
Western-style diet often leads to food overconsumption, which triggers the development of comorbidities, such as obesity, insulin resistance, hypercholesterolemia, hypertriglyceridemia, type 2 diabetes, and heart failure (HF). Several studies suggest that intermittent fasting (IF) protects against the development of those morbidities. This study presents evidence of the beneficial effects of IF on HF. Based on the current evidence, we discuss the potential molecular mechanisms by which IF works and where liver ketone bodies (KBs) play important roles. There is evidence that IF promotes a metabolic switch in highly metabolic organs, such as the heart, which increases the use of KBs during fasting. However, besides their role as energy substrates, KBs participate in the signaling pathways that control the expression of genes involved in oxidative stress protection and metabolism. Several molecular factors, such as adenosine monophosphate-activated protein kinase (AMPK), peroxisome proliferatoractivated receptor, fibroblast growth factor 21 (FGF21), sirtuins, and nuclear factor erythroid 2-related factor 2 (Nrf2) are involved. Furthermore, IF appears to maintain circadian rhythm, which is essential for highly metabolically active organs. Finally, we highlight the important research topics that need to be pursued to improve current knowledge and strengthen the potential of IF as a preventive and therapeutic approach to HF.
Assuntos
Diabetes Mellitus Tipo 2 , Insuficiência Cardíaca , Sirtuínas , Proteínas Quinases Ativadas por AMP , Monofosfato de Adenosina , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Mellitus Tipo 2/terapia , Jejum/fisiologia , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/terapia , Humanos , Corpos Cetônicos/metabolismo , Fator 2 Relacionado a NF-E2RESUMO
The prevalence of the metabolic syndrome (MetS) and its cardiac comorbidities as cardiac hypertrophy (CH) have increased considerably due to the high consumption of carbohydrates, such as sucrose and/or fructose. We compared the effects of sucrose (S), fructose (F) and their combination (S + F) on the development of MetS in weaned male Wistar rats and established the relationship between the consumption of these sugars and the degree of cardiac CH development, oxidative stress (OS) and Calcium/calmodulin-dependent protein kinase type II subunit delta oxidation (ox-CaMKIIδ). 12 weeks after the beginning of treatments with S, F or S + F, arterial pressure was measured and 8 weeks later (to complete 20 weeks) the animals were sacrificed and blood samples, visceral adipose tissue and hearts were obtained. Biochemical parameters were determined in serum and cardiac tissue to evaluate the development of MetS and OS. To evaluate CH, atrial natriuretic peptide (ANP), CaMKIIδ and ox-CaMKIIδ were determined by western blot and histological studies were performed in cardiac tissue. Our data showed that chronic consumption of S + F exacerbates MetS-induced CH which is related with a higher OS and ox-CaMKIIδ.
Assuntos
Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Cardiomegalia/enzimologia , Carboidratos da Dieta/efeitos adversos , Frutose/efeitos adversos , Síndrome Metabólica/enzimologia , Miocárdio/enzimologia , Estresse Oxidativo/efeitos dos fármacos , Sacarose/efeitos adversos , Animais , Carboidratos da Dieta/farmacologia , Frutose/farmacologia , Masculino , Oxirredução/efeitos dos fármacos , Ratos , Ratos Wistar , Sacarose/farmacologiaRESUMO
AIMS: Ventricular myocytes (VM) depolarization activates L-type Ca2+ channels (LCC) allowing Ca2+ influx (ICa) to synchronize sarcoplasmic reticulum (SR) Ca2+ release, via Ca2+-release channels (RyR2). The resulting whole-cell Ca2+ transient triggers contraction, while cytosolic Ca2+ removal by SR Ca2+ pump (SERCA2) and sarcolemmal Na+/Ca2+ exchanger (NCX) allows relaxation. In diseased hearts, extensive VM remodeling causes heterogeneous, blunted and slow Ca2+ transients. Among remodeling changes are: A) T-tubules disorganization. B) Diminished SERCA2 and low SR Ca2+. However, those often overlap, hindering their relative contribution to contractile dysfunction (CD). Furthermore, few studies have assessed their specific impact on the spatiotemporal Ca2+ transient properties and contractile dynamics simultaneously. Therefore, we sought to perform a quantitative comparison of how heterogeneous and slow Ca2+ transients, with different underlying determinants, affect contractile performance. METHODS: We used two experimental models: A) formamide-induced acute "detubulation", where VM retain functional RyR2 and SERCA2, but lack T-tubules-associated LCC and NCX. B) Intact VM from hypothyroid rats, presenting decreased SERCA2 and SR Ca2+, but maintained T-tubules. By confocal imaging of Fluo-4-loaded VM, under field-stimulation, simultaneously acquired Ca2+ transients and shortening, allowing direct correlations. KEY FINDINGS: We found near-linear correlations among key parameters of altered Ca2+ transients, caused independently by T-tubules disruption or decreased SR Ca2+, and shortening and relaxation, SIGNIFICANCE: Unrelated structural and molecular alterations converge in similarly abnormal Ca2+ transients and CD, highlighting the importance of independently reproduce disease-specific alterations, to quantitatively assess their impact on Ca2+ signaling and contractility, which would be valuable to determine potential disease-specific therapeutic targets.
Assuntos
Ventrículos do Coração/citologia , Contração Miocárdica , Miócitos Cardíacos/enzimologia , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Retículo Sarcoplasmático/enzimologia , Animais , Cálcio/metabolismo , Sinalização do Cálcio , Citosol/metabolismo , Formamidas , Hipotireoidismo/patologia , Masculino , Ratos Wistar , Fatores de TempoRESUMO
Stress-induced cardiomyopathy (SIC) results from a profound catecholaminergic surge during strong emotional or physical stress. SIC is characterized by acute left ventricular apex hypokinesia, in the absence of coronary arteries occlusion, and can lead to arrhythmias and acute heart failure. Although, most SIC patients recover, the process could be slow, and recurrence or death may occur. Despite that the SIC common denominator is a large catecholamine discharge, the pathophysiological mechanism is incompletely understood. It is thought that catecholamines have direct cytotoxicity on apical ventricular myocytes (VM), which have the highest ß-adrenergic receptors density, and whose overstimulation might cause acute Ca2+ overload and oxidative stress, causing death in some VM and stunning others. Rodents receiving acute isoproterenol (ISO) overdose (OV) mimic SIC development, however, they have not been used to simultaneously assess Ca2+ handling and contractility status in isolated VM, which might explain ventricular hypokinesia. Therefore, treating rats with a single ISO-OV (67â¯mg/kg body weight), we sought out to characterize, with confocal imaging, Ca2+ and shortening dynamics in Fluo-4-loaded VM, during the early (1-5 days) and late post-acute phases (15 days). We found that ISO-OV VM showed contractile dysfunction; blunted shortening with slower force development and relaxation. These correlated with Ca2+ mishandling; blunted Ca2+ transient, with slower time to peak and SR Ca2+ recovery. SR Ca2+ content was low, nevertheless, diastolic Ca2+ sparks were more frequent, and their duration increased. Contractility and Ca2+ dysfunction aggravated or remained altered over time, explaining slow recovery. We conclude that diminished VM contractility is the main determinant of ISO-OV hypokinesia and is mostly related to Ca2+ mishandling.
Assuntos
Sinalização do Cálcio , Cardiomiopatias/fisiopatologia , Separação Celular , Ventrículos do Coração/patologia , Contração Miocárdica , Miócitos Cardíacos/patologia , Animais , Cálcio/metabolismo , Cardiomiopatias/metabolismo , Citosol/metabolismo , Diástole , Modelos Animais de Doenças , Overdose de Drogas , Ventrículos do Coração/fisiopatologia , Isoproterenol , Masculino , Miócitos Cardíacos/metabolismo , Ratos Wistar , Retículo Sarcoplasmático/metabolismo , Sístole , Fatores de TempoRESUMO
Hypothyroidism (Hypo) is a risk factor for cardiovascular diseases, including heart failure. Hypo rapidly induces Ca2+ mishandling and contractile dysfunction (CD), as well as atrophy and ventricular myocytes (VM) remodeling. Hypo decreases SERCA-to-phospholamban ratio (SERCA/PLB), and thereby contributes to CD. Nevertheless, detailed spatial and temporal Ca2+ cycling characterization in VM is missing, and contribution of other structural and functional changes to the mechanism underlying Ca2+ mishandling and CD, as transverse tubules (T-T) remodeling, mitochondrial density (Dmit) and energy availability, is unclear. Therefore, in a rat model of Hypo, we aimed to characterize systolic and diastolic Ca2+ signaling, T-T remodeling, Dmit, citrate synthase (CS) activity and high-energy phosphate metabolites (ATP and phosphocreatine). We confirmed a decrease in SERCA/PLB (59%), which slowed SERCA activity (48%), reduced SR Ca2+ (19%) and blunted Ca2+ transient amplitude (41%). Moreover, assessing the rate of SR Ca2+ release (dRel/dt), we found that early and maximum dRel/dt decreased, and this correlated with staggered Ca2+ transients. However, dRel/dt persisted during Ca2+ transient relaxation due to abundant late Ca2+ sparks. Isoproterenol significantly up-regulated systolic Ca2+ cycling. T-T were unchanged, hence, cannot explain staggered Ca2+ transients and altered dRel/dt. Therefore, we suggest that these might be caused by RyR2 clusters desynchronization, due to diminished Ca2+-dependent sensitivity of RyR2, which also caused a decrease in diastolic SR Ca2+ leak. Furthermore, Dmit was unchanged and CS activity slightly decreased (14%), however, the ratio phosphocreatine/ATP did not change, therefore, energy deficiency cannot account for Ca2+ and contractility dysregulation. We conclude that decreased SR Ca2+, due to slower SERCA, disrupts systolic RyR2 synchronization, and this underlies CD.
Assuntos
Hipotireoidismo/fisiopatologia , Contração Miocárdica/fisiologia , Miócitos Cardíacos/patologia , Animais , Atrofia , Cálcio/metabolismo , Sinalização do Cálcio/efeitos dos fármacos , Citrato (si)-Sintase/metabolismo , Modelos Animais de Doenças , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/patologia , Hipotireoidismo/sangue , Masculino , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Contração Miocárdica/efeitos dos fármacos , Miocárdio/metabolismo , Miocárdio/patologia , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Ratos Wistar , Retículo Sarcoplasmático/efeitos dos fármacos , Retículo Sarcoplasmático/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Sístole/efeitos dos fármacos , Tapsigargina/farmacologia , Hormônios Tireóideos/sangue , Fatores de TempoRESUMO
Patients with breast cancer (BC) overexpressing HER2 (HER2+) are selected for Trastuzumab treatment, which blocks HER2 and improves cancer prognosis. However, HER2+ diagnosis, by the gold standard, immunohistochemistry, could lead to errors, associated to: a) variability in sample manipulation (thin 2D sections), b) use of subjective algorithms, and c) heterogeneity of HER2 expression within the tissue. Therefore, we explored HER2 3D detection by multiplexed imaging of Affibody-Quantum Dots conjugates (Aff-QD), ratiometric analysis (RMAFI) and thresholding, using BC multicellular tumor spheroids (BC-MTS) (~120 µm of diameter) as 3D model of BC. HER2+, HER2- and hybrid HER2+/- BC-MTS (mimicking heterogeneous tissue) were incubated simultaneously with two Aff-QD probes (anti-HER2 and negative control (NC), respectively, (1:1)). Confocal XY sections were recorded along the Z distance, and processed by automatized RMAFI (anti-HER2 Aff-QD/ NC). Quantifying the NC fluorescence allowed to predict the fraction of non-specific accumulation of the anti-HER2 probe within the thick sample, and resolve the specific HER2 level. HER2 was detected up to 30µm within intact BC-MTS, however, permeabilization improved detection up to 70µm. Specific HER2 signal was objectively quantified, and HER2 3D-density of 9.2, 48.3 and 30.8% were obtained in HER2-, HER2+ and hybrid HER2+/- permeabilized BC-MTS, respectively. Therefore, by combining the multiplexing capacity of Aff-QD probes and RMAFI, we overcame the challenge of non-specific probe accumulation in 3D samples with minimal processing, yielding a fast, specific spatial HER2 detection and objective quantification.
RESUMO
Cardiac hypertrophy is a compensatory mechanism maladapted because it presents an increase in the oxidative stress which could be associated with the development of the heart failure. A mechanism proposed is by mitochondrial DNA (mtDNA) oxidation, which evolved to a vicious cycle because of the synthesis of proteins encoded in the genome is committed. Therefore, the aim of the present work was to evaluate the mtDNA damage and enzyme repairing the 8-oxo-deoxyguanosine glycosylase mitochondrial isoform 1-2a (OGG1-2a) in the early stage of compensated cardiac hypertrophy induced by abdominal aortic constriction (AAC). Results showed that after 6 weeks of AAC, hearts presented a compensated hypertrophy (22%), with an increase in the cell volume (35%), mitochondrial mass (12%), and mitochondrial membrane potential (94%). However, the increase of oxidative stress did not affect mtDNA most probably because OGG1-2a was found to increase 3.2 times in the mitochondrial fraction. Besides, mitochondrial function was not altered by the cardiac hypertrophy condition but in vitro mitochondria from AAC heart showed an increased sensibility to stress induced by the high Ca2+ concentration. The increase in the oxidative stress in compensated cardiac hypertrophy induced the OGG1-2a migration to mitochondria to repair mtDNA oxidation, as a mechanism that allows maintaining the cardiac function in the compensatory stage.
Assuntos
Cardiomegalia/patologia , Dano ao DNA , DNA Glicosilases/metabolismo , DNA Mitocondrial/metabolismo , Mitocôndrias/metabolismo , 8-Hidroxi-2'-Desoxiguanosina , Animais , Cardiomegalia/fisiopatologia , Desoxiguanosina/análogos & derivados , Desoxiguanosina/metabolismo , Modelos Animais de Doenças , Ventrículos do Coração/citologia , Ventrículos do Coração/fisiopatologia , Humanos , Masculino , Potencial da Membrana Mitocondrial , Miócitos Cardíacos/metabolismo , Oxirredução , Estresse Oxidativo , Isoformas de Proteínas/metabolismo , Transporte Proteico , Ratos WistarRESUMO
In Ca(2+)-overloaded ventricular myocytes, SERCA is crucial to steadily achieve the critical sarcoplasmic reticulum (SR) Ca(2+) level to trigger and sustain Ca(2+) waves, that propagate at constant rate (Êwave). High luminal Ca(2+) sensitizes RyR2, thereby increasing Ca(2+) sparks frequency, and the larger RyR2-mediated SR Ca(2+) flux (dF/dt) sequentially activates adjacent RyR2 clusters. Recently, it was proposed that rapid SERCA Ca(2+) reuptake, ahead of the wave front, further sensitizes RyR2, increasing Êwave. Nevertheless, this is controversial because rapid cytosolic Ca(2+) removal could instead impair RyR2 activation. We assessed whether rapid SR Ca(2+) uptake enhances Êwave by changing SERCA activity (Ò¡Decay) over a large range (â¼175%). We used normal (Ctrl) and hyperthyroid rat (HT; reduced phospholamban by â¼80%) myocytes treated with thapsigargin or isoproterenol (ISO). We found that Êwave and dF/dt had a non-linear dependency with Ò¡Decay, while Ca(2+) waves amplitude was largely unaffected. Furthermore, SR Ca(2+) also showed a non-linear dependency with Ò¡Decay, however, the relationships Êwave vs. SR Ca(2+) and Êwave vs. dF/dt were linear, suggesting that high steady state SR Ca(2+) determines Êwave, while rapid SERCA Ca(2+) uptake does not. Finally, ISO did not increase Êwave in HT cells, therefore, ISO-enhanced Êwave in Ctrl depended on high SR Ca(2+).
Assuntos
Cálcio/metabolismo , Ventrículos do Coração/metabolismo , Miócitos Cardíacos/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Retículo Sarcoplasmático/metabolismo , Animais , Sinalização do Cálcio , Proteínas de Ligação ao Cálcio/química , Citosol/metabolismo , Modelos Animais de Doenças , Hipertireoidismo/metabolismo , Isoproterenol/química , Masculino , Ratos , Ratos Wistar , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Tapsigargina/químicaRESUMO
ETHNOPHARMACOLOGICAL RELEVANCE: Traditional or folk medicine has led to the discovery of important bioactive substances used in several health-related areas. Phytochemicals in Rhoeo discolor (R. discolor) extracts have proven to have important cancer cell specific cytotoxic activity. In the present research, we determined the cytotoxic effect of extracts of R. discolor, a plant commonly used in Mexico for both medicinal and ornamental purposes. AIM OF THE STUDY: We evaluated the cytotoxic effects against three representative human cancer cell lines: HT-29 colon cancer, Hep-G2 liver cancer and PC-3 prostate cancer cell lines, as well as a control fibroblast cell line NIH 3T3. MATERIALS AND METHODS: Ten different crude extracts were tested along with fractions derived from the five most bioactive crude extracts. Analytical data, HPLC-MS-TOF, revealed a high content of phenolic compounds such as anthocyanins, ferulic, vanillic, chlorogenic and p-coumaric acid in the extracts. Phenolic compounds have previously been reported as health beneficial with antioxidant and potential cancer specific cytotoxic effects. RESULTS: Studies revealed that low concentrations of these crude bioactive extracts (10µg/ml) and their fractions (50µg/ml) were effective as cancer specific cytotoxic agents, since they caused a significant proliferation inhibition on cancer cell lines (up to 94.2% in HT-29, 92.9% in Hep-G2 and 61.8% in PC-3 of apoptosis induction) with little harm to the control cell line (no higher than 28.3% apoptosis induction), and, importantly, the most effective extracts were mainly water, methanol and ethanol based. CONCLUSIONS: These results suggest that a diet containing these compounds may function as a medical aid or chemoprotective.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Neoplasias/tratamento farmacológico , Extratos Vegetais/farmacologia , Solventes/química , Tradescantia/química , Animais , Antineoplásicos Fitogênicos/isolamento & purificação , Antineoplásicos Fitogênicos/toxicidade , Apoptose/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Relação Dose-Resposta a Droga , Etanol/química , Células HT29 , Células Hep G2 , Humanos , Espectrometria de Massas , Metanol/química , Camundongos , Células NIH 3T3 , Neoplasias/patologia , Fitoterapia , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/toxicidade , Folhas de Planta , Plantas Medicinais , Água/químicaRESUMO
BACKGROUND/AIMS: Pressure-overload (PO) causes cardiac hypertrophy (CH), and eventually leads to heart failure (HF). HF ventricular myocytes present transverse-tubules (TT) loss or disarrangement and decreased sarcoplasmic reticulum (SR) density, and both contribute to altered Ca2+ signaling and heart dysfunction. It has been shown that TT remodeling precedes HF, however, it is unknown whether SR structural and functional remodeling also starts early in CH. METHODS: Using confocal microscopy, we assessed TT (with Di-8-ANNEPS) and SR (with SR-trapped Mag-Fluo-4) densities, as well as SR fluorophore diffusion (fluorescence recovery after photobleach; FRAP), cytosolic Ca2+ signaling and ex vivo cardiac performance in a PO rat hypertrophy model induced by abdominal aortic constriction (at 6 weeks). RESULTS: Rats developed CH, while cardiac performance, basal and upon ß-adrenergic stimulation, remained unaltered. TT density decreased by â¼14%, without spatial disarrangement, while SR density decreased by â¼7%. More important, FRAP was â¼30% slower, but with similar maximum recovery, suggesting decreased SR interconnectivity. Systolic and diastolic Ca2+ signaling and SR Ca2+ content were unaltered. CONCLUSION: SR remodeling is an early CH event, similar to TT remodeling, appearing during compensated hypertrophy. Nevertheless, myocytes can withstand those moderate structural changes in SR and TT, preserving normal Ca2+ signaling and contractility.
Assuntos
Cardiomegalia/patologia , Microtúbulos/metabolismo , Retículo Sarcoplasmático/metabolismo , Compostos de Anilina/química , Animais , Cálcio/metabolismo , Sinalização do Cálcio , Cardiomegalia/metabolismo , Células Cultivadas , Modelos Animais de Doenças , Recuperação de Fluorescência Após Fotodegradação , Corantes Fluorescentes/química , Íons/química , Íons/metabolismo , Masculino , Microscopia Confocal , Microtúbulos/patologia , Miócitos Cardíacos/citologia , Miócitos Cardíacos/metabolismo , Pressão , Ratos , Ratos Wistar , Retículo Sarcoplasmático/patologia , Xantenos/químicaRESUMO
AIMS: Obesity and diabetes mellitus type 2 (DM2) frequently coexist and increase the propensity of cardiovascular dysfunction by numerous mechanisms. Chief among them are oxidative stress and Ca(2+) dysregulation, and both are inducers of the mitochondrial permeability transition pore (MPTP). Nevertheless, it is unknown whether MPTP formation is triggered in DM2 animals, and thereby contributing to cardiac dysfunction. We assessed MPTP sensitivity and reactive oxygen species production in cardiac mitochondria, as well as cytosolic Ca(2+) handling in ventricular myocytes from rats with DM2. MAIN METHODS: Male Zucker Fa/fa rats (Fa/fa) 32weeks old presenting DM2, concentric hypertrophy, and diastolic dysfunction were used. MPTP formation was evaluated in isolated mitochondria and Ca(2+) handling in ventricular myocytes, by spectrophotometric and confocal microscope techniques, respectively. KEY FINDINGS: We found that the systolic Ca(2+) transient relaxation was ~40% slower, while mitochondrial H2O2 production increased by ~6-fold. MPTP opening in isolated mitochondria from Fa/fa (mFa/fa) was more sensitive to Ca(2+) than in mitochondria from lean rats (mLean), and correlated with increased thiol group exposure. The mFa/fa showed decreased oxidative phosphorylation capacity. The ATP content decreased in myocytes, while the PCr/ATP ratio remained unchanged and caspase 9 activity largely increased in myocytes from Fa/fa animals. SIGNIFICANCE: Our results showed that oxidative stress and diastolic Ca(2+) dysregulation increased MPTP sensitivity leading to mitochondrial dysfunction and apoptosis. Mitochondrial dysfunction could compromise ATP synthesis, and lower ATP could be linked to decreased SERCA2 activity, which might underlie diastolic dysfunction. Prolonged Ca(2+) transients might further exacerbate mitochondrial dysfunction.
Assuntos
Diabetes Mellitus Tipo 2/fisiopatologia , Cardiopatias/fisiopatologia , Mitocôndrias Cardíacas/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Estresse Oxidativo , Animais , Atractilosídeo/análogos & derivados , Atractilosídeo/metabolismo , Sinalização do Cálcio , Diabetes Mellitus Tipo 2/complicações , Cardiopatias/diagnóstico por imagem , Cardiopatias/etiologia , Leptina/sangue , Lipídeos/sangue , Masculino , Potencial da Membrana Mitocondrial , Mitocôndrias Cardíacas/patologia , Translocases Mitocondriais de ADP e ATP/metabolismo , Poro de Transição de Permeabilidade Mitocondrial , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Consumo de Oxigênio , Permeabilidade , Ratos , Ratos Zucker , UltrassonografiaRESUMO
Stress-induced cardiomyopathy, triggered by acute catecholamine discharge, is a syndrome characterized by transient, apical ballooning linked to acute heart failure and ventricular arrhythmias. Rats receiving an acute isoproterenol (ISO) overdose (OV) suffer cardiac apex ischemia-reperfusion damage and arrhythmia, and then undergo cardiac remodeling and dysfunction. Nevertheless, the subcellular mechanisms underlying cardiac dysfunction after acute damage subsides are not thoroughly understood. To address this question, Wistar rats received a single ISO injection (67 mg/kg). We found in vivo moderate systolic and diastolic dysfunction at 2 wk post-ISO-OV; however, systolic dysfunction recovered after 4 wk, while diastolic dysfunction worsened. At 2 wk post-ISO-OV, cardiac function was assessed ex vivo, while mitochondrial oxidative metabolism and stress were assessed in vitro, and Ca(2+) handling in ventricular myocytes. These were complemented with sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA), phospholamban (PLB), and RyR2 expression studies. Ex vivo, basal mechanical performance index (MPI) and oxygen consumption rate (MVO2) were unchanged. Nevertheless, upon increase of metabolic demand, by ß-adrenergic stimulation (1-100 nM ISO), the MPI versus MVO2 relation decreased and shifted to the right, suggesting MPI and mitochondrial energy production uncoupling. Mitochondria showed decreased oxidative metabolism, membrane fragility, and enhanced oxidative stress. Myocytes presented systolic and diastolic Ca(2+) mishandling, and blunted response to ISO (100 nM), and all these without apparent changes in SERCA, PLB, or RyR2 expression. We suggest that post-ISO-OV mitochondrial dysfunction may underlie decreased cardiac contractility, mainly by depletion of ATP needed for myofilaments and Ca(2+) transport by SERCA, while exacerbated oxidative stress may enhance diastolic RyR2 activity.
Assuntos
Sinalização do Cálcio , Cardiomiopatias/metabolismo , Traumatismo por Reperfusão Miocárdica/metabolismo , Estresse Oxidativo , Agonistas Adrenérgicos/toxicidade , Animais , Proteínas de Ligação ao Cálcio/genética , Proteínas de Ligação ao Cálcio/metabolismo , Cardiomiopatias/etiologia , Cardiomiopatias/fisiopatologia , Células Cultivadas , Ventrículos do Coração/citologia , Ventrículos do Coração/metabolismo , Ventrículos do Coração/fisiopatologia , Isoproterenol/toxicidade , Camundongos , Mitocôndrias Cardíacas/metabolismo , Contração Miocárdica , Traumatismo por Reperfusão Miocárdica/fisiopatologia , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Consumo de Oxigênio , Ratos , Ratos Wistar , Canal de Liberação de Cálcio do Receptor de Rianodina/genética , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/genética , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismoAssuntos
Anquirinas/biossíntese , Arritmias Cardíacas/metabolismo , Proteínas Musculares/biossíntese , Miocárdio/metabolismo , Processamento Alternativo/genética , Animais , Anquirinas/genética , Arritmias Cardíacas/genética , Cromossomos Humanos Par 4/genética , Cromossomos Humanos Par 4/metabolismo , Éxons/genética , Feminino , Humanos , Masculino , Camundongos , Proteínas Musculares/genética , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Transcrição Gênica/genéticaRESUMO
En la Quebrada de Humahuaca se usan, en forma indiscriminada e inadecuada plaguicidas cada vez más toxicos, entre ellos los organofosfordos carbamatos. Los plaguicidas son una amenaza para las personas de todas las edades, pero son los niños quienes enfrentan el mayor riesgo. Teniendo en cuenta que los efectos tempranos en el desarrikki ubfabtuk se oyedeb detectar mediante pruebas neuroconductuales, se elegió etudiar algunos de los efectos en escolares expuestos versus escolares no expuestos residente en la Quebrada de Humahuaca. Se optó por un estudio de corte trasversal, de tipo exploratorio, cuantitativo de tipo cuasi-experimental. Se introdujeron criterios de inclusión para tratar de homogenizar la muestra. Se optó como variable de exposición determinar niveles de aceticolinesterasa, sérico y plasmática y como variables deefectos de desempeño en el rendimiento de pruebas neuroconductuales que evaluara la motricidad fina, la atención sostenida y la memoria de trabajo con sus tres subsistemas: Agenda Viso-Espacial, Bucle fonológico y Ejecutivo Central. Se encontró un rendimiento significativamente diferente en las funcions de Memoria de trabajo, entre los grupos expuestos y no expuestos. En este estudio la función cognitiva que más se afecta es la Memoria de trabajo, en particular el subsistema Agenda Viso-Espacial. Los plaguicidas ejercen un efecto deteriorante mayor si la exposición abarca el período prenatal.
Assuntos
Humanos , Criança , Criança , Proteção da Criança , Uso de Praguicidas , Praguicidas/efeitos adversos , Transtornos Relacionados ao Uso de Substâncias , Toxicidade/efeitos adversos , Argentina/epidemiologiaRESUMO
Excitation-contraction coupling in cardiac myocytes occurs by Ca2+-induced Ca2+ release, where L-type Ca2+ current evokes a larger sarcoplasmic reticulum (SR) Ca2+ release. The Ca2+-induced Ca2+ release amplification factor or gain (SR Ca2+ release/I(Ca)) is usually assessed by the V(m) dependence of current and Ca2+ transients. Gain rises at negative V(m), as does single channel I(Ca) (i(Ca)), which has led to the suggestion that the increases of i(Ca) amplitude enhances gain at more negative V(m). However, I(Ca) = NP(o) x i(Ca) (where NP(o) is the number of open channels), and NP(o) and i(Ca) both depend on V(m). To assess how i(Ca) and NP(o) separately influence Ca2+-induced Ca2+ release, we measured I(Ca) and junctional SR Ca2+ release in voltage-clamped rat ventricular myocytes using "Ca2+ spikes" (confocal microscopy). To vary i(Ca) alone, we changed [Ca2+](o) rapidly at constant test V(m) (0 mV) or abruptly repolarized from +120 mV to different V(m) (at constant [Ca2+](o)). To vary NP(o) alone, we altered Ca2+ channel availability by varying holding V(m) (at constant test V(m)). Reducing either i(Ca) or NP(o) alone increased excitation-contraction coupling gain. Thus, increasing i(Ca) does not increase gain at progressively negative test V(m). Such enhanced gain depends on lower NP(o) and reduced redundant Ca2+ channel openings (per junction) and a consequently smaller denominator in the gain equation. Furthermore, modest i(Ca) (at V(m) = 0 mV) may still effectively trigger SR Ca2+ release, whereas at positive V(m) (and smaller i(Ca)), high and well-synchronized channel openings are required for efficient excitation-contraction coupling. At very positive V(m), reduced i(Ca) must explain reduced SR Ca2+ release.
Assuntos
Canais de Cálcio/metabolismo , Sinalização do Cálcio , Ativação do Canal Iônico , Contração Miocárdica , Miócitos Cardíacos/metabolismo , Retículo Sarcoplasmático/metabolismo , Potenciais de Ação , Animais , Cafeína/farmacologia , Cálcio/metabolismo , Canais de Cálcio/efeitos dos fármacos , Canais de Cálcio Tipo L/metabolismo , Sinalização do Cálcio/efeitos dos fármacos , Estimulação Elétrica , Ativação do Canal Iônico/efeitos dos fármacos , Cinética , Potenciais da Membrana , Microscopia Confocal , Miócitos Cardíacos/efeitos dos fármacos , Técnicas de Patch-Clamp , Ratos , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Retículo Sarcoplasmático/efeitos dos fármacosRESUMO
Ca(2+) current (I(Ca)) recovery from inactivation is necessary for normal cardiac excitation-contraction coupling. In normal hearts, increased stimulation frequency increases force, but in heart failure (HF) this force-frequency relationship (FFR) is often flattened or reversed. Although reduced sarcoplasmic reticulum Ca(2+)-ATPase function may be involved, decreased I(Ca) availability may also contribute. Longer action potential duration (APD), slower intracellular Ca(2+) concentration ([Ca(2+)](i)) decline, and higher diastolic [Ca(2+)](i) in HF could all slow I(Ca) recovery from inactivation, thereby decreasing I(Ca) availability. We measured the effect of different diastolic [Ca(2+)](i) on I(Ca) inactivation and recovery from inactivation in rabbit cardiac myocytes. Both I(Ca) and Ba(2+) current (I(Ba)) were measured. I(Ca) decay was accelerated only at high diastolic [Ca(2+)](i) (600 nM). I(Ba) inactivation was slower but insensitive to [Ca(2+)](i). Membrane potential dependence of I(Ca) or I(Ba) availability was not affected by [Ca(2+)](i) <600 nM. Recovery from inactivation was slowed by both depolarization and high [Ca(2+)](i). We also used perforated patch with action potential (AP)-clamp and normal Ca(2+) transients, using various APDs as conditioning pulses for different frequencies (and to simulate HF APD). Recovery of I(Ca) following longer APD was increasingly incomplete, decreasing I(Ca) availability. Trains of long APs caused a larger I(Ca) decrease than short APD at the same frequency. This effect on I(Ca) availability was exacerbated by slowing twitch [Ca(2+)](i) decline by approximately 50%. We conclude that long APD and slower [Ca(2+)](i) decline lead to cumulative inactivation limiting I(Ca) at high heart rates and might contribute to the negative FFR in HF, independent of altered Ca(2+) channel properties.
Assuntos
Potenciais de Ação/fisiologia , Canais de Cálcio Tipo L/fisiologia , Cálcio/metabolismo , Ativação do Canal Iônico/fisiologia , Contração Miocárdica/fisiologia , Miócitos Cardíacos/fisiologia , Animais , Células Cultivadas , CoelhosRESUMO
Glycoside-induced cardiac inotropy has traditionally been attributed to direct Na(+)-K(+)-ATPase inhibition, causing increased intracellular [Na(+)] and consequent Ca(2+) gain via the Na(+)-Ca(2+) exchanger (NCX). However, recent studies suggested alternative mechanisms of glycoside-induced inotropy: (1) direct activation of sarcoplasmic reticulum Ca(2+) release channels (ryanodine receptors; RyRs); (2) increased Ca(2+) selectivity of Na(+) channels (slip-mode conductance); and (3) other signal transduction pathways. None of these proposed mechanisms requires NCX or an altered [Na(+)] gradient. Here we tested the ability of ouabain (OUA, 3 microm), digoxin (DIG, 20 microm) or acetylstrophanthidin (ACS, 4 microm) to alter Ca(2+) transients in completely Na(+)-free conditions in intact ferret and cat ventricular myocytes. We also tested whether OUA directly activates RyRs in permeabilized cat myocytes (measuring Ca(2+) sparks by confocal microscopy). In intact ferret myocytes (stimulated at 0.2 Hz), DIG and ACS enhanced Ca(2+) transients and cell shortening during twitches, as expected. However, prior depletion of [Na(+)](i) (in Na(+)-free, Ca(2+)-free solution) and in Na(+)-free solution (replaced by Li(+)) the inotropic effects of DIG and ACS were completely prevented. In voltage-clamped cat myocytes, OUA increased Ca(2+) transients by 48 +/- 4% but OUA had no effect in Na(+)-depleted cells (replaced by N-methyl-d-glucamine). In permeabilized cat myocytes, OUA did not change Ca(2+) spark frequency, amplitude or spatial spread (although spark duration was slightly prolonged). We conclude that the acute inotropic effects of DIG, ACS and OUA (and the effects on RyRs) depend on the presence of Na(+) and a functional NCX in ferret and cat myocytes (rather than alternate Na(+)-independent mechanisms).
Assuntos
Glicosídeos Cardíacos/farmacologia , Cardiotônicos/farmacologia , Ventrículos do Coração/efeitos dos fármacos , Trocador de Sódio e Cálcio/metabolismo , Animais , Proteínas de Bactérias/farmacologia , Sinalização do Cálcio , Gatos , Digoxina/farmacologia , Furões , Ventrículos do Coração/citologia , Ventrículos do Coração/metabolismo , Técnicas In Vitro , Potenciais da Membrana , Contração Miocárdica , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Ouabaína/farmacologia , Técnicas de Patch-Clamp , Canal de Liberação de Cálcio do Receptor de Rianodina/efeitos dos fármacos , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Sódio/metabolismo , Estreptolisinas/farmacologia , Estrofantidina/análogos & derivados , Estrofantidina/farmacologiaRESUMO
En el presente estudio se revisaron 98 expedientes clínicos completos pertenecientes a pacientes que estuvieron ingresados en los diferentes departamentos del Hospital Antonio Lenín Fonseca durante el período diciembre 2004 a enero 2005 y que se les prescribieron fluroquinolonas con el objetivo de evaluar el uso terapeútico de dichos fármacos. La información fue obtenida del expediente clínico, así como del perfil fármaco terapeútico y registros de enfermería, recolectada a través de una ficha de datos conteniendo las variables en estudio. Se encontró que la mayoría de los pacientes eran de edad adulta, portadores de enfermedades crónicas. El departamento que más utiliza fluroquinolnas fue Medicina Interna, los fármacos más utilizados fueron Gatifloxacina, Ciprofloxacino y Levofloxacino. Las indicaciones más comunes fueron infección de vías respiratorias inferiores, infección de vías urinarias y pie diabético. Concluyendo que el uso de Fluroquinolonas en el Hospital Antonio Lenín Fonseca durante el período estudiado fue inadecuado...
Assuntos
Adulto , Ciprofloxacina , Ciprofloxacina/farmacologia , Ciprofloxacina , Ciprofloxacina/uso terapêutico , Ofloxacino/farmacologia , Ofloxacino/uso terapêutico , Quinolonas/farmacologia , Quinolonas , Quinolonas/uso terapêuticoRESUMO
After sarcoplasmic reticulum (SR) Ca2+ depletion in intact ventricular myocytes, electrical activity promotes SR Ca2+ reloading and recovery of twitch amplitude. In ferret, recovery of twitch and caffeine-induced contracture required fewer twitches than in rabbit or rat. In rat, there was no difference in action potential duration at 90% repolarization (APD90) at steady state (SS) versus at the first post-depletion (PD) twitch. The SS APD90 was similar in ferret and rabbit (but longer than in rat). However, compared to SS, the PD APD90 was lengthened in ferret, but shortened in rabbit. When rabbit myocytes were subjected to AP-clamp patterns during SR Ca2+ reloading (ferret- or rabbit-type APs), reloading was much faster using the ferret AP templates. We conclude that the faster SR Ca2+ refilling in ferret is due to the increased Ca2+ influx during the longer PD AP. The PD versus SS APD90 difference was suppressed by thapsigargin in ferret (indicating Ca2+ dependence). In rabbit, the PD AP shortening depended on the preceding diastolic interval (rather than Ca2+), because rest produced the same AP shortening, and SS APD90 increased as a function of frequency (in contrast to ferret). Transient outward current (Ito) was larger and recovered from inactivation much faster in ferret than in rabbit. Moreover, slow Ito recovery (tau approximately 3 s) in rabbit was a much larger fraction of Ito. Our data and a computational model (including two Ito components) suggest that in rabbit the slowly recovering Ito is responsible for short post-rest and PD APs, for the unusual frequency dependence of APD90, and ultimately for the slower post-depletion SR Ca2+ reloading.