RESUMEN
BACKGROUND: While calcium is known to play a crucial role in mammalian sperm physiology, how it flows in and out of the male gamete is not completely understood. Herein, we investigated the involvement of Na+/Ca2+ exchangers (NCX) in mammalian sperm capacitation. Using the pig as an animal model, we first confirmed the presence of NCX1 and NCX2 isoforms in the sperm midpiece. Next, we partially or totally blocked Ca2+ outflux (forward transport) via NCX1/NCX2 with different concentrations of SEA0400 (2-[4-[(2,5-difluorophenyl)methoxy]phenoxy]-5-ethoxyaniline; 0, 0.5, 5 and 50 µM) and Ca2+ influx (reverse transport) with SN6 (ethyl 2-[[4-[(4-nitrophenyl)methoxy]phenyl]methyl]-1,3-thiazolidine-4-carboxylate; 0, 0.3, 3 or 30 µM). Sperm were incubated under capacitating conditions for 180 min; after 120 min, progesterone was added to induce the acrosome reaction. At 0, 60, 120, 130, and 180 min, sperm motility, membrane lipid disorder, acrosome integrity, mitochondrial membrane potential (MMP), tyrosine phosphorylation of sperm proteins, and intracellular levels of Ca2+, reactive oxygen species (ROS) and superoxides were evaluated. RESULTS: Partial and complete blockage of Ca2+ outflux and influx via NCX induced a significant reduction of sperm motility after progesterone addition. Early alterations on sperm kinematics were also observed, the effects being more obvious in totally blocked than in partially blocked samples. Decreased sperm motility and kinematics were related to both defective tyrosine phosphorylation and mitochondrial activity, the latter being associated to diminished MMP and ROS levels. As NCX blockage did not affect the lipid disorder of plasma membrane, the impaired acrosome integrity could result from reduced tyrosine phosphorylation. CONCLUSIONS: Inhibition of outflux and influx of Ca2+ triggered similar effects, thus indicating that both forward and reverse Ca2+ transport through NCX exchangers are essential for sperm capacitation.
Asunto(s)
Calcio , Intercambiador de Sodio-Calcio , Capacitación Espermática , Animales , Masculino , Capacitación Espermática/efectos de los fármacos , Intercambiador de Sodio-Calcio/metabolismo , Intercambiador de Sodio-Calcio/efectos de los fármacos , Calcio/metabolismo , Porcinos , Espermatozoides/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Motilidad Espermática/efectos de los fármacos , Reacción Acrosómica/efectos de los fármacos , Potencial de la Membrana Mitocondrial/efectos de los fármacosRESUMEN
BACKGROUND/AIMS: Monensin, an Na ionophore, increases intracellular Na ([Na]i). Alteration of [Na]i influences ion transport through the sarcolemmal membrane. So far, the effects of monensin on ventricular myocytes have not been examined in detail. The main objective of this study was to elucidate the mechanism via which monensin-evoked increases in [Na]i affect the membrane potential and currents in ventricular myocytes of guinea pigs. METHODS: Membrane potentials and currents were measured using the whole-cell patch-clamp technique in single myocytes. The concentration of intracellular Ca ([Ca]i) was evaluated by measuring fluorescence intensity of Fluo-4. RESULTS: Monensin (10-5M) shortened the action potential duration (APD) and reduced the amplitude of the plateau phase. In addition, monensin decreased the sodium current (INa) and shifted the inactivation curve to the hyperpolarized direction. Moreover, it decreased the L-type calcium current (ICa). However, this effect was attenuated by increasing the buffering capacity of [Ca]i. The Na-Ca exchange current (INa-Ca) was activated particularly in the reverse mode. Na-K pump current (INa-K) was also activated. Notably, the inward rectifying K current (IK1) was not affected, and the change in the delayed outward K current (IK) was not evident. CONCLUSION: These results suggest that the monensin-induced shortened APD and reduced amplitude of the plateau phase are primarily due to the decrease in the ICa, the activation of the reverse mode of INa-Ca, and the increased INa-K, and second due to the decreased INa. The IK and the IK1 may not be associated with the abovementioned changes induced by monensin. The elevation of [Na]i can exert multiple influences on electrophysiological phenomena in cardiac myocytes.
Asunto(s)
Monensina/farmacología , Miocitos Cardíacos/efectos de los fármacos , Ionóforos de Sodio/farmacología , Sodio/metabolismo , Potenciales de Acción/efectos de los fármacos , Animales , Calcio/metabolismo , Cardiotónicos/farmacología , Cationes/metabolismo , Células Cultivadas , Técnicas Electrofisiológicas Cardíacas , Cobayas , Espacio Intracelular/efectos de los fármacos , Espacio Intracelular/metabolismo , Masculino , Potenciales de la Membrana/efectos de los fármacos , Microscopía Fluorescente , Miocitos Cardíacos/metabolismo , Ouabaína/farmacología , Técnicas de Placa-Clamp , Potasio/metabolismo , Intercambiador de Sodio-Calcio/efectos de los fármacos , ATPasa Intercambiadora de Sodio-Potasio/efectos de los fármacosRESUMEN
The effect of KB-R7943, an inhibitor of the plasmalemmal Na+-Ca2+ exchanger, on mitochondrial Ca2+ transporters was examined with membrane-permeabilized cardiomyocyte-derived H9c2 cells expressing the fluorescent Ca2+ indicator, yellow cameleon 3.1, in the mitochondria. KB-R7943, as well as ruthenium red, inhibited the rise in mitochondrial Ca2+ on increasing the extramitochondrial Ca2+ concentration from 0 nM to 300 nM. CGP-37157, but not KB-R7943, inhibited the decline in mitochondrial Ca2+on return to Ca2+ free extramitochondrial solution. These results indicated that KB-R7943 has inhibitory effects on the mitochondrial Ca2+ uniporter, but not on the mitochondrial Na+-Ca2+ exchanger.
Asunto(s)
Canales de Calcio/efectos de los fármacos , Calcio/metabolismo , Intercambiador de Sodio-Calcio/efectos de los fármacos , Tiourea/análogos & derivados , Animales , Membrana Celular/metabolismo , Células Cultivadas , Clonazepam/análogos & derivados , Clonazepam/farmacología , Mitocondrias/metabolismo , Miocitos Cardíacos/efectos de los fármacos , Ratas , Sodio/metabolismo , Intercambiador de Sodio-Calcio/metabolismo , Tiazepinas/farmacología , Tiourea/farmacologíaRESUMEN
Intracellular Na elevation in the heart is a hallmark of pathologies where both acute and chronic metabolic remodelling occurs. Here, we assess whether acute (75 µM ouabain 100 nM blebbistatin) or chronic myocardial Nai load (PLM3SA mouse) are causally linked to metabolic remodelling and whether the failing heart shares a common Na-mediated metabolic 'fingerprint'. Control (PLMWT), transgenic (PLM3SA), ouabain-treated and hypertrophied Langendorff-perfused mouse hearts are studied by 23Na, 31P, 13C NMR followed by 1H-NMR metabolomic profiling. Elevated Nai leads to common adaptive metabolic alterations preceding energetic impairment: a switch from fatty acid to carbohydrate metabolism and changes in steady-state metabolite concentrations (glycolytic, anaplerotic, Krebs cycle intermediates). Inhibition of mitochondrial Na/Ca exchanger by CGP37157 ameliorates the metabolic changes. In silico modelling indicates altered metabolic fluxes (Krebs cycle, fatty acid, carbohydrate, amino acid metabolism). Prevention of Nai overload or inhibition of Na/Camito may be a new approach to ameliorate metabolic dysregulation in heart failure.
Asunto(s)
Reprogramación Celular/fisiología , Citoplasma/metabolismo , Insuficiencia Cardíaca/metabolismo , Miocardio/metabolismo , Sodio/metabolismo , Animales , Modelos Animales de Enfermedad , Metabolismo Energético , Técnicas de Sustitución del Gen , Corazón , Hipertrofia , Preparación de Corazón Aislado , Masculino , Enfermedades Metabólicas/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Ratas , Ratas Wistar , Sodio/sangre , Intercambiador de Sodio-Calcio/efectos de los fármacos , Tiazepinas/farmacologíaRESUMEN
Calcineurin inhibitors (CNIs) are immunosuppressive drugs used to prevent graft rejection after organ transplant. Common side effects include renal magnesium wasting and hypomagnesemia, which may contribute to new-onset diabetes mellitus, and hypercalciuria, which may contribute to post-transplant osteoporosis. Previous work suggested that CNIs reduce the abundance of key divalent cation transport proteins, expressed along the distal convoluted tubule, causing renal magnesium and calcium wasting. It has not been clear, however, whether these effects are specific for the distal convoluted tubule, and whether these represent off-target toxic drug effects, or result from inhibition of calcineurin. The CNI tacrolimus can inhibit calcineurin only when it binds with the immunophilin, FKBP12; we previously generated mice in which FKBP12 could be deleted along the nephron, to test whether calcineurin inhibition is involved, these mice are normal at baseline. Here, we confirmed that tacrolimus-treated control mice developed hypomagnesemia and urinary calcium wasting, with decreased protein and mRNA abundance of key magnesium and calcium transport proteins (NCX-1 and Calbindin-D28k ). However, qPCR also showed decreased mRNA expression of NCX-1 and Calbindin-D28k , and TRPM6. In contrast, KS-FKBP12-/- mice treated with tacrolimus were completely protected from these effects. These results indicate that tacrolimus affects calcium and magnesium transport along the distal convoluted tubule and strongly suggests that inhibition of the phosphatase, calcineurin, is directly involved.
Asunto(s)
Inhibidores de la Calcineurina/farmacología , Calcio/metabolismo , Hipercalciuria/inducido químicamente , Túbulos Renales Distales/efectos de los fármacos , Magnesio/metabolismo , Proteína 1A de Unión a Tacrolimus/genética , Tacrolimus/farmacología , Desequilibrio Hidroelectrolítico/inducido químicamente , Animales , Calbindina 1/efectos de los fármacos , Calbindina 1/genética , Calbindina 1/metabolismo , Inhibidores de la Calcineurina/efectos adversos , Calcio/orina , Expresión Génica , Hipercalciuria/metabolismo , Hipercalciuria/orina , Túbulos Renales Distales/metabolismo , Magnesio/orina , Ratones , Ratones Noqueados , ARN Mensajero/efectos de los fármacos , ARN Mensajero/metabolismo , Intercambiador de Sodio-Calcio/efectos de los fármacos , Intercambiador de Sodio-Calcio/genética , Intercambiador de Sodio-Calcio/metabolismo , Canales Catiónicos TRPM/efectos de los fármacos , Canales Catiónicos TRPM/genética , Canales Catiónicos TRPM/metabolismo , Tacrolimus/efectos adversos , Proteína 1A de Unión a Tacrolimus/metabolismo , Desequilibrio Hidroelectrolítico/metabolismo , Desequilibrio Hidroelectrolítico/orinaRESUMEN
Chronic ethanol (EtOH) exposure can cause intracellular Ca overload by stimulating calcium channel receptors and trigger apoptosis of neurons. NCX3 may play a cytoprotective role in intracellular Ca excretion. In this study, the effect of EtOH on NCX3 was analyzed by observing NCX3 expression in the hippocampus of chronic EtOH-exposed male C57BL/6 mice. Mice were divided into a control group, a 10% EtOH group, and a 20% EtOH group for 30, 60, and 90 days. Behavioral changes were observed using the Morris water maze. The protein and mRNA expressions of NCX3 and their distribution in the hippocampus were observed by western blotting, quantitative PCR, and immunohistochemistry staining. The results showed that EtOH exposure exerted a significant adverse effect on the spatial memory capacity of mice. Increased expression of calpain-1 and cleaved caspase-3 proteins indicated increased apoptosis. The expression of NCX3 in the hippocampus was downregulated after exposure to EtOH (except 10% EtOH for 30 days) and this inhibition was time and dose dependent with EtOH exposure. The level of p-Akt, which is an upstream regulation factor of NCX3, showed a trend similar to that of NCX3 protein. Chronic EtOH exposure reduced the expression of NCX3 in the hippocampus of male C57BL/6 mice, increasing intracellular calcium and apoptosis, resulting in spatial memory impairment in mice.
Asunto(s)
Depresores del Sistema Nervioso Central/toxicidad , Etanol/toxicidad , Hipocampo/efectos de los fármacos , Intercambiador de Sodio-Calcio/efectos de los fármacos , Intercambiador de Sodio-Calcio/metabolismo , Animales , Hipocampo/metabolismo , Aprendizaje/efectos de los fármacos , Masculino , Memoria/efectos de los fármacos , Ratones , Ratones Endogámicos C57BLAsunto(s)
Canales de Calcio/metabolismo , Mitocondrias Cardíacas/metabolismo , Infarto del Miocardio/metabolismo , Animales , Antiarrítmicos/uso terapéutico , Calcio/sangre , Canales de Calcio/efectos de los fármacos , Humanos , Ratones , Mitocondrias Cardíacas/fisiología , Infarto del Miocardio/tratamiento farmacológico , Infarto del Miocardio/fisiopatología , Miocitos Cardíacos/química , Miocitos Cardíacos/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Intercambiador de Sodio-Calcio/antagonistas & inhibidores , Intercambiador de Sodio-Calcio/efectos de los fármacos , Intercambiador de Sodio-Calcio/uso terapéuticoRESUMEN
BACKGROUND: Long QT syndrome mutations in the SCN5A gene are associated with an enhanced late sodium current (INa,L) which may lead to pro-arrhythmic action potential prolongation and intracellular calcium dysregulation. We here investigated the dynamic relation between INa,L, intracellular sodium ([Na+]i) and calcium ([Ca2+]i) homeostasis and pro-arrhythmic events in the setting of a SCN5A mutation. METHODS AND RESULTS: Wild-type (WT) and Scn5a1798insD/+ (MUT) mice (age 3-5â¯months) carrying the murine homolog of the SCN5A-1795insD mutation on two distinct genetic backgrounds (FVB/N and 129P2) were studied. [Na+]i, [Ca2+]i and Ca2+ transient amplitude were significantly increased in 129P2-MUT myocytes as compared to WT, but not in FVB/N-MUT. Accordingly, INa,L wassignificantly more enhanced in 129P2-MUT than in FVB/N-MUT myocytes, consistent with a dose-dependent correlation. Quantitative RT-PCR analysis revealed intrinsic differences in mRNA expression levels of the sodium/potassium pump, the sodium/hydrogen exchanger, and sodiumcalcium exchanger between the two mouse strains. The rate of increase in [Na+]i, [Ca2+]i and Ca2+ transient amplitude following the application of the Na+/K+-ATPase inhibitor ouabain was significantly greater in 129P2-MUT than in 129P2-WT myocytes and was normalized by the INa,L inhibitor ranolazine. Furthermore, ranolazine decreased the incidence of pro-arrhythmic calcium after-transients elicited in 129P2-MUT myocytes. CONCLUSIONS: In this study we established a causal link between the magnitude of INa,L, extent of Na+ and Ca2+ dysregulation, and incidence of pro-arrhythmic events in murine Scn5a1798insD/+ myocytes. Furthermore, our findings provide mechanistic insight into the anti-arrhythmic potential of pharmacological inhibition of INa,L in patients with LQT3 syndrome.
Asunto(s)
Arritmias Cardíacas/genética , Arritmias Cardíacas/fisiopatología , Calcio/fisiología , Líquido Intracelular/fisiología , Canal de Sodio Activado por Voltaje NAV1.5/fisiología , Sodio/fisiología , Animales , Arritmias Cardíacas/etiología , Células Cultivadas , Líquido Intracelular/efectos de los fármacos , Ratones , Ratones de la Cepa 129 , Ratones Endogámicos C57BL , Ratones Transgénicos , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/fisiología , Bloqueadores de los Canales de Sodio/farmacología , Bloqueadores de los Canales de Sodio/uso terapéutico , Intercambiador de Sodio-Calcio/efectos de los fármacos , Intercambiador de Sodio-Calcio/fisiologíaRESUMEN
We have previously demonstrated that methylene blue (MB) counteracts the effects of hydrogen sulfide (H2S) cardiotoxicity by improving cardiomyocyte contractility and intracellular Ca2+ homeostasis disrupted by H2S poisoning. In vivo, MB restores cardiac contractility severely depressed by sulfide and protects against arrhythmias, ranging from bundle branch block to ventricular tachycardia or fibrillation. To dissect the cellular mechanisms by which MB reduces arrhythmogenesis and improves bioenergetics in myocytes intoxicated with H2S, we evaluated the effects of H2S on resting membrane potential (Em), action potential (AP), Na+/Ca2+ exchange current (INaCa), depolarization-activated K+ currents and ATP levels in adult mouse cardiac myocytes and determined whether MB could counteract the toxic effects of H2S on myocyte electrophysiology and ATP. Exposure to toxic concentrations of H2S (100 µM) significantly depolarized Em, reduced AP amplitude, prolonged AP duration at 90% repolarization (APD90), suppressed INaCa and depolarization-activated K+ currents, and reduced ATP levels in adult mouse cardiac myocytes. Treating cardiomyocytes with MB (20 µg/ml) 3 min after H2S exposure restored Em, APD90, INaCa, depolarization-activated K+ currents, and ATP levels toward normal. MB improved mitochondrial membrane potential (∆ψm) and oxygen consumption rate in myocytes in which Complex I was blocked by rotenone. We conclude that MB ameliorated H2S-induced cardiomyocyte toxicity at multiple levels: (1) reversing excitation-contraction coupling defects (Ca2+ homeostasis and L-type Ca2+ channels); (2) reducing risks of arrhythmias (Em, APD, INaCa and depolarization-activated K+ currents); and (3) improving cellular bioenergetics (ATP, ∆ψm).
Asunto(s)
Adenosina Trifosfato/metabolismo , Arritmias Cardíacas/inducido químicamente , Arritmias Cardíacas/prevención & control , Metabolismo Energético/efectos de los fármacos , Sulfuro de Hidrógeno/toxicidad , Canales Iónicos/efectos de los fármacos , Azul de Metileno/farmacología , Miocitos Cardíacos/efectos de los fármacos , Potenciales de Acción , Animales , Arritmias Cardíacas/metabolismo , Arritmias Cardíacas/fisiopatología , Canales de Calcio Tipo L/efectos de los fármacos , Canales de Calcio Tipo L/metabolismo , Señalización del Calcio/efectos de los fármacos , Frecuencia Cardíaca/efectos de los fármacos , Canales Iónicos/metabolismo , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Ratones , Mitocondrias Cardíacas/efectos de los fármacos , Mitocondrias Cardíacas/metabolismo , Contracción Miocárdica/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Consumo de Oxígeno/efectos de los fármacos , Canales de Potasio con Entrada de Voltaje/efectos de los fármacos , Canales de Potasio con Entrada de Voltaje/metabolismo , Intercambiador de Sodio-Calcio/efectos de los fármacos , Intercambiador de Sodio-Calcio/metabolismoRESUMEN
BACKGROUND: The cardiac sodium/calcium (Na+/Ca2+) exchanger (NCX) contributes to diastolic depolarization in cardiac pacemaker cells. Increased NCX activity has been found in heart failure and atrial fibrillation. The influence of increased NCX activity on resting heart rate, beta-adrenergic-mediated increase in heart rate, and cardiac conduction properties is unknown. OBJECTIVE: The purpose of this study was to investigate the influence of NCX overexpression in a homozygous transgenic whole-heart mouse model (NCX-OE) on sinus and AV nodal function. METHODS: Langendorff-perfused, beating whole hearts of NCX-OE and the corresponding wild-type (WT) were studied ± isoproterenol (ISO; 0.2 µM). Epicardial ECG, AV nodal Wenckebach cycle length (AVN-WCL), and retrograde AVN-WCL were obtained. RESULTS: At baseline, basal heart rate was unaltered between NCX-OE and WT (WT: cycle length [CL] 177.6 ± 40.0 ms, no. of hearts [n] = 20; NCX-OE: CL 185.9 ± 30.5 ms, n = 18; P = .21). In the presence of ISO, NCX-OE exhibited a significantly higher heart rate compared to WT (WT: CL 133.4 ± 13.4 ms, n = 20; NCX-OE: CL 117.7 ± 14.2 ms, n = 18; P <.001). ISO led to a significant shortening of the anterograde and retrograde AVN-WCL without differences between NCX-OE and WT. CONCLUSION: This study is the first to demonstrate that increased NCX activity enhances beta-adrenergic increase of heart rate. Mechanistically, increased NCX inward mode activity may promote acceleration of diastolic depolarization in sinus nodal pacemaker cells, thus enhancing chronotropy in NCX-OE. These findings suggest a novel potential therapeutic target for heart rate control in the presence of increased NCX activity, such as heart failure.
Asunto(s)
Insuficiencia Cardíaca/tratamiento farmacológico , Frecuencia Cardíaca/fisiología , Isoproterenol/farmacología , Contracción Miocárdica/fisiología , Miocitos Cardíacos/patología , Nodo Sinoatrial/fisiopatología , Intercambiador de Sodio-Calcio/biosíntesis , Agonistas Adrenérgicos beta/farmacología , Animales , Calcio/metabolismo , Modelos Animales de Enfermedad , Insuficiencia Cardíaca/metabolismo , Ratones , Ratones Transgénicos , Miocitos Cardíacos/metabolismo , Nodo Sinoatrial/metabolismo , Intercambiador de Sodio-Calcio/efectos de los fármacosRESUMEN
The quintessential property of developing cardiomyocytes is their ability to beat spontaneously. The mechanisms underlying spontaneous beating in developing cardiomyocytes are thought to resemble those of adult heart, but have not been directly tested. Contributions of sarcoplasmic and mitochondrial Ca(2+)-signaling vs. If-channel in initiating spontaneous beating were tested in human induced Pluripotent Stem cell-derived cardiomyocytes (hiPS-CM) and rat Neonatal cardiomyocytes (rN-CM). Whole-cell and perforated-patch voltage-clamping and 2-D confocal imaging showed: (1) both cell types beat spontaneously (60-140/min, at 24°C); (2) holding potentials between -70 and 0mV had no significant effects on spontaneous pacing, but suppressed action potential formation; (3) spontaneous pacing at -50mV activated cytosolic Ca(2+)-transients, accompanied by in-phase inward current oscillations that were suppressed by Na(+)-Ca(2+)-exchanger (NCX)- and ryanodine receptor (RyR2)-blockers, but not by Ca(2+)- and If-channels blockers; (4) spreading fluorescence images of cytosolic Ca(2+)-transients emanated repeatedly from preferred central cellular locations during spontaneous beating; (5) mitochondrial un-coupler, FCCP at non-depolarizing concentrations (â¼50nM), reversibly suppressed spontaneous pacing; (6) genetically encoded mitochondrial Ca(2+)-biosensor (mitycam-E31Q) detected regionally diverse, and FCCP-sensitive mitochondrial Ca(2+)-uptake and release signals activating during INCX oscillations; (7) If-channel was absent in rN-CM, but activated only negative to -80mV in hiPS-CM; nevertheless blockers of If-channel failed to alter spontaneous pacing.
Asunto(s)
Señalización del Calcio/fisiología , Frecuencia Cardíaca/fisiología , Mitocondrias Cardíacas/fisiología , Miocitos Cardíacos/fisiología , Animales , Bloqueadores de los Canales de Calcio/farmacología , Señalización del Calcio/efectos de los fármacos , Línea Celular , Células Cultivadas , Humanos , Ratones , Modelos Animales , Miocitos Cardíacos/citología , Técnicas de Placa-Clamp , Ratas , Canal Liberador de Calcio Receptor de Rianodina/efectos de los fármacos , Canal Liberador de Calcio Receptor de Rianodina/fisiología , Intercambiador de Sodio-Calcio/antagonistas & inhibidores , Intercambiador de Sodio-Calcio/efectos de los fármacos , Intercambiador de Sodio-Calcio/fisiologíaRESUMEN
BACKGROUND: Fibroblast growth factor (FGF)-23 is a key regulator of phosphate homeostasis. Higher FGF-23 levels are correlated with poor outcomes in cardiovascular diseases. FGF-23 can produce cardiac hypertrophy and increase intracellular calcium, which can change cardiac electrical activity. However, it is not clear whether FGF-23 possesses arrhythmogenic potential through calcium dysregulation. Therefore, the purposes of this study were to evaluate the electrophysiological effects of FGF-23 and identify the underlying mechanisms. METHODS: Patch clamp, confocal microscope with Fluo-4 fluorescence, and Western blot analyses were used to evaluate the electrophysiological characteristics, calcium homeostasis and calcium regulatory proteins in HL-1 atrial myocytes with and without FGF-23 (10 and 25 ng/mL) incubation for 24 h. RESULTS: FGF-23 (25 ng/mL) increased L-type calcium currents, calcium transient and sarcoplasmic reticulum Ca(2+) contents in HL-1 cells. FGF-23 (25 ng/mL)-treated cells (n = 14) had greater incidences (57%, 17% and 15%, P < 0·05) of delayed afterdepolarizations than control (n = 12) and FGF-23 (10 ng/mL)-treated cells (n = 13). Compared with control cells, FGF-23 (25 ng/mL)-treated cells (n = 14) exhibited increased phosphorylation of calcium/calmodulin-dependent protein kinase IIδ and phospholamban (PLB) at threonine 17 but had similar phosphorylation extents of PLB at serine 16, total PLB and sarcoplasmic reticulum Ca(2+) -ATPase protein. Moreover, the FGF receptor inhibitor (PD173074, 10 nM), calmodulin inhibitor (W7, 5 µM) and phospholipase C inhibitor (U73122, 1 µM) attenuated the effects of FGF-23 on calcium/calmodulin-dependent protein kinase II phosphorylation. CONCLUSIONS: FGF-23 increases HL-1 cells arrhythmogenesis with calcium dysregulation through modulating calcium-handling proteins.
Asunto(s)
Calcio/metabolismo , Factores de Crecimiento de Fibroblastos/fisiología , Homeostasis/fisiología , Potenciales de Acción/efectos de los fármacos , Arritmias Cardíacas/fisiopatología , Proteínas de Unión al Calcio/efectos de los fármacos , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/antagonistas & inhibidores , Células Cultivadas , Relación Dosis-Respuesta a Droga , Estrenos/farmacología , Factor-23 de Crecimiento de Fibroblastos , Factores de Crecimiento de Fibroblastos/farmacología , Atrios Cardíacos/metabolismo , Homeostasis/efectos de los fármacos , Humanos , Miocitos Cardíacos/metabolismo , Técnicas de Placa-Clamp , Inhibidores de Proteínas Quinasas/farmacología , Pirimidinas/farmacología , Pirrolidinonas/farmacología , Intercambiador de Sodio-Calcio/efectos de los fármacos , Sulfonamidas/farmacologíaRESUMEN
Considerable electrophysiological and pharmacological evidence has long suggested an important role for acetylcholine in the regulation of rapid-eye-movement (REM) sleep. For example, injection of the cholinergic agonist carbachol into the dorsomedial pons produces an REM sleep-like state with muscle atonia and cortical activation, both of which are cardinal features of REM sleep. Located within this region of the pons is the sublaterodorsal nucleus (SLD), a structure thought to be both necessary and sufficient for generating REM sleep muscle atonia. Subsets of glutamatergic SLD neurons potently contribute to motor inhibition during REM sleep through descending projections to motor-related glycinergic/GABAergic neurons in the spinal cord and ventromedial medulla. Prior electrophysiological and pharmacological studies examining the effects of acetylcholine on SLD neurons have, however, produced conflicting results. In the present study, we sought to clarify how acetylcholine influences the activity of spinally projecting SLD (SLDsp) neurons. We used retrograde tracing in combination with patch-clamp recordings and recorded pre- and postsynaptic effects of carbachol on SLDsp neurons. Carbachol acted presynaptically by increasing the frequency of glutamatergic miniature excitatory postsynaptic currents. We also found that carbachol directly excited SLDsp neurons by activating an Na(+)-Ca(2+) exchanger. Both pre- and postsynaptic effects were mediated by co-activation of M1 and M3 muscarinic receptors. These observations suggest that acetylcholine produces synergistic, excitatory pre- and postsynaptic responses on SLDsp neurons that, in turn, probably serve to promote muscle atonia during REM sleep.
Asunto(s)
Carbacol/farmacología , Neuronas Colinérgicas/efectos de los fármacos , Neuronas Motoras/efectos de los fármacos , Agonistas Muscarínicos/farmacología , Puente/efectos de los fármacos , Médula Espinal/efectos de los fármacos , Acetilcolina/metabolismo , Animales , Neuronas Colinérgicas/metabolismo , Potenciales Postsinápticos Excitadores/efectos de los fármacos , Femenino , Ácido Glutámico/metabolismo , Técnicas In Vitro , Masculino , Ratones Endogámicos C57BL , Potenciales Postsinápticos Miniatura/efectos de los fármacos , Neuronas Motoras/metabolismo , Inhibición Neural/efectos de los fármacos , Vías Nerviosas/efectos de los fármacos , Vías Nerviosas/metabolismo , Puente/metabolismo , Terminales Presinápticos/efectos de los fármacos , Terminales Presinápticos/metabolismo , Receptor Muscarínico M1/agonistas , Receptor Muscarínico M1/metabolismo , Receptor Muscarínico M3/agonistas , Receptor Muscarínico M3/metabolismo , Transducción de Señal/efectos de los fármacos , Sueño REM/efectos de los fármacos , Intercambiador de Sodio-Calcio/efectos de los fármacos , Intercambiador de Sodio-Calcio/metabolismo , Médula Espinal/metabolismo , Factores de TiempoRESUMEN
Ginkgo biloba has been used for medical purposes for centuries in traditional Chinese medicine. Ginkgo biloba extract 50 (GBE50) is a new standardized GBE product that matches the standardized German product as EGb761. This paper is aimed at studying the cardio-protection effects of GBE50 Salvia miltiorrhiza on myocardial function, area at risk, myocardial ultra-structure, and expression of calcium handling proteins in rat ischemic myocardium. Myocardium ischemia was induced by the left anterior descending (LAD) coronary artery occlusion and myocardial function was recorded by a transducer advanced into the left ventricle on a computer system. In vitro myocardial infarction was measured by 2,3,5-triphenyltetrazolium chloride (TTC) and Evans blue staining of heart sections. Morphological change was evaluated by electric microscopy and Western blotting was used for protein expression. Hemodynamic experiments in vivo showed that postischemic cardiac contractile function was reduced in ischemic rats. Salvia miltiorrhiza (7.5 g/kg/d×7) and Ginkgo biloba extract 50 (GBE50) (100 mg/kg/d×7) improved post-schemic cardiac diastolic dysfunction while not affecting the systolic function. In hearts of GBE50 group and Salvia miltiorrhiza (SM) group, the area at risk was significantly reduced and myocardial structure was better-preserved. Moreover, Naâº-Ca²âº exchanger (NCX) expression increase and sarcoplasmic reticulum Ca²âº-ATPase 2 (SERCA2), LTCC, and ryanodine receptor 2 (RyR2) expression decreases were smaller than those in ischemia group. There was a significant difference between the GBE50 and ischemia group in NCX expression. GBE50 could improve recovery in contractile function and prevent myocardium from ischemia damage, which may be caused by attenuating the abnormal expression of NCX.
Asunto(s)
Cardiotónicos/farmacología , Ginkgo biloba , Corazón/efectos de los fármacos , Infarto del Miocardio , Fitoterapia/métodos , Extractos Vegetales/farmacología , Salvia miltiorrhiza , Función Ventricular Izquierda/efectos de los fármacos , Animales , Canales de Calcio Tipo L/efectos de los fármacos , Canales de Calcio Tipo L/metabolismo , Frecuencia Cardíaca/efectos de los fármacos , Masculino , Microscopía Electrónica , Contracción Miocárdica/efectos de los fármacos , Daño por Reperfusión Miocárdica , Miocardio/ultraestructura , Ratas , Canal Liberador de Calcio Receptor de Rianodina/efectos de los fármacos , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/efectos de los fármacos , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismo , Intercambiador de Sodio-Calcio/efectos de los fármacos , Intercambiador de Sodio-Calcio/metabolismoRESUMEN
The treatment of heart failure (HF) is challenging and morbidity and mortality are high. The goal of this study was to determine if inhibition of the late Na(+) current with ranolazine during early hypertensive heart disease might slow or stop disease progression. Spontaneously hypertensive rats (aged 7 mo) were subjected to echocardiographic study and then fed either control chow (CON) or chow containing 0.5% ranolazine (RAN) for 3 mo. Animals were then restudied, and each heart was removed for measurements of t-tubule organization and Ca(2+) transients using confocal microscopy of the intact heart. RAN halted left ventricular hypertrophy as determined from both echocardiographic and cell dimension (length but not width) measurements. RAN reduced the number of myocytes with t-tubule disruption and the proportion of myocytes with defects in intracellular Ca(2+) cycling. RAN also prevented the slowing of the rate of restitution of Ca(2+) release and the increased vulnerability to rate-induced Ca(2+) alternans. Differences between CON- and RAN-treated animals were not a result of different expression levels of voltage-dependent Ca(2+) channel 1.2, sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a, ryanodine receptor type 2, Na(+)/Ca(2+) exchanger-1, or voltage-gated Na(+) channel 1.5. Furthermore, myocytes with defective Ca(2+) transients in CON rats showed improved Ca(2+) cycling immediately upon acute exposure to RAN. Increased late Na(+) current likely plays a role in the progression of cardiac hypertrophy, a key pathological step in the development of HF. Early, chronic inhibition of this current slows both hypertrophy and development of ultrastructural and physiological defects associated with the progression to HF.
Asunto(s)
Acetanilidas/farmacología , Señalización del Calcio/efectos de los fármacos , Hipertensión/tratamiento farmacológico , Miocitos Cardíacos/efectos de los fármacos , Piperazinas/farmacología , Bloqueadores de los Canales de Sodio/farmacología , Canales de Sodio/efectos de los fármacos , Sodio/metabolismo , Animales , Canales de Calcio Tipo L/efectos de los fármacos , Canales de Calcio Tipo L/metabolismo , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Relación Dosis-Respuesta a Droga , Insuficiencia Cardíaca/etiología , Insuficiencia Cardíaca/metabolismo , Insuficiencia Cardíaca/fisiopatología , Insuficiencia Cardíaca/prevención & control , Hipertensión/complicaciones , Hipertensión/diagnóstico por imagen , Hipertensión/metabolismo , Hipertensión/fisiopatología , Hipertrofia Ventricular Izquierda/etiología , Hipertrofia Ventricular Izquierda/metabolismo , Hipertrofia Ventricular Izquierda/fisiopatología , Hipertrofia Ventricular Izquierda/prevención & control , Masculino , Miocitos Cardíacos/metabolismo , Canal de Sodio Activado por Voltaje NAV1.5/efectos de los fármacos , Canal de Sodio Activado por Voltaje NAV1.5/metabolismo , Ranolazina , Ratas , Ratas Endogámicas SHR , Canal Liberador de Calcio Receptor de Rianodina/efectos de los fármacos , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismo , Canales de Sodio/metabolismo , Intercambiador de Sodio-Calcio/efectos de los fármacos , Intercambiador de Sodio-Calcio/metabolismo , Factores de Tiempo , UltrasonografíaAsunto(s)
Angina de Pecho/tratamiento farmacológico , Angina de Pecho/fisiopatología , Calcio/sangre , Enfermedad de la Arteria Coronaria/tratamiento farmacológico , Enfermedad de la Arteria Coronaria/fisiopatología , Hipercalcemia/tratamiento farmacológico , Hipercalcemia/fisiopatología , Isquemia Miocárdica/tratamiento farmacológico , Isquemia Miocárdica/fisiopatología , Canales de Sodio/fisiología , Intercambiador de Sodio-Calcio/fisiología , Acetanilidas/uso terapéutico , Antagonistas Adrenérgicos beta/uso terapéutico , Angina de Pecho/diagnóstico , Fibrilación Atrial/diagnóstico , Fibrilación Atrial/tratamiento farmacológico , Fibrilación Atrial/fisiopatología , Benzazepinas/uso terapéutico , Bloqueadores de los Canales de Calcio/uso terapéutico , Fármacos Cardiovasculares/uso terapéutico , Enfermedad de la Arteria Coronaria/diagnóstico , Electrocardiografía/efectos de los fármacos , Endotelio Vascular/fisiopatología , Insuficiencia Cardíaca Diastólica/diagnóstico , Insuficiencia Cardíaca Diastólica/tratamiento farmacológico , Insuficiencia Cardíaca Diastólica/fisiopatología , Humanos , Hipercalcemia/diagnóstico , Ivabradina , Isquemia Miocárdica/diagnóstico , Nitratos/uso terapéutico , Piperazinas/uso terapéutico , Ranolazina , Sodio/metabolismo , Canales de Sodio/efectos de los fármacos , Intercambiador de Sodio-Calcio/efectos de los fármacosRESUMEN
BACKGROUND: Epidemiological studies revealed significantly lower mortality rates in cancer patients receiving cardiac glycosides, which turned on interest in the anticancer properties of these drugs. However, cardiac glycosides have also been shown to stimulate cell growth in several cell types. In the present investigation we analyzed the pro-death and pro-survival properties of ouabain in the human lymphoma derived cell line U937. METHODS: ROS, intracellular Ca++, cell cycle were evaluated by loading the cells with fluorescent probes under cytofluorimetry. Cell counts and evaluation of trypan blue-excluding cells were performed under optic microscope. Protein detection was done by specific antibodies after protein separation from cellular lysates by SDS-PAGE and transfer blot. RESULTS: High doses of ouabain cause ROS generation, elevation of [Ca++]i and death of lymphoma derived U937 cells. Lower doses of OUA activate a survival pathway in which plays a role the Na+/Ca++-exchanger (NCX), active in the Ca++ influx mode rather than in the Ca++ efflux mode. Also p38 MAPK plays a pro-survival role. However, the activation of this MAPK does not appear to depend on NCX. CONCLUSION: This investigation shows that the cardiac glycoside OUA is cytotoxic also for the lymphoma derived cell line U937 and that can activate a survival pathway in which are involved NCX and p38 MAPK. These molecules can represent potential targets of combined therapy.
Asunto(s)
Calcio/metabolismo , Ouabaína/administración & dosificación , Especies Reactivas de Oxígeno/metabolismo , Intercambiador de Sodio-Calcio , Muerte Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Citometría de Flujo , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Linfoma/genética , Linfoma/metabolismo , Intercambiador de Sodio-Calcio/efectos de los fármacos , Intercambiador de Sodio-Calcio/metabolismo , Células U937 , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
The late Na current is of pathophysiological importance for the heart. Ranolazine is an innovative anti-ischemic and antianginal agent that inhibits the late Na current, thereby reducing the Na-dependent Ca-overload, which improves diastolic tone and oxygen handling during myocardial ischemia. In addition, ranolazine seems to exert beneficial effects on diastolic cardiac function. Moreover, there are experimental and clinical data about its antiarrhythmic properties. A beneficial atrial selectivity of ranolazine has been suggested that may be helpful for the treatment of atrial fibrillation. The purpose of this review article is to discuss possible future clinical indications based on novel experimental and preclinical results and the significance of the available data.
Asunto(s)
Acetanilidas/uso terapéutico , Arritmias Cardíacas/tratamiento farmacológico , Inhibidores Enzimáticos/uso terapéutico , Insuficiencia Cardíaca Diastólica/tratamiento farmacológico , Piperazinas/uso terapéutico , Potenciales de Acción/efectos de los fármacos , Antiarrítmicos/uso terapéutico , Fibrilación Atrial/tratamiento farmacológico , Calcio/metabolismo , Fármacos Cardiovasculares/uso terapéutico , Cationes/metabolismo , Diástole/efectos de los fármacos , Insuficiencia Cardíaca/tratamiento farmacológico , Humanos , Contracción Miocárdica/efectos de los fármacos , Canal de Sodio Activado por Voltaje NAV1.5/efectos de los fármacos , Ranolazina , Sodio/metabolismo , Intercambiador de Sodio-Calcio/efectos de los fármacosRESUMEN
The mechanisms by which NaCl raises blood pressure (BP) in hypertension are unresolved, but much evidence indicates that endogenous ouabain is involved. In rodents, arterial smooth muscle cell (ASMC) Na(+) pumps with an α(2)-catalytic subunit (ouabain EC(50) ≤1.0 nM) are crucial for some hypertension models, even though ≈80% of ASMC Na(+) pumps have an α(1)-subunit (ouabain EC(50) ≈ 5 µM). Human α(1)-Na(+) pumps, however, have high ouabain affinity (EC(50) ≈ 10-20 nM). We used immunoblotting, immunocytochemistry, and Ca(2+) imaging (fura-2) to examine the expression, distribution, and function of Na(+) pump α-subunit isoforms in human arteries and primary cultured human ASMCs (hASMCs). hASMCs express α(1)- and α(2)-Na(+) pumps. Further, α(2)-, but not α(1)-, pumps are confined to plasma membrane microdomains adjacent to sarcoplasmic reticulum (SR), where they colocalize with Na/Ca exchanger-1 (NCX1) and C-type transient receptor potential-6 (receptor-operated channels, ROCs). Prolonged inhibition (72 h) with 100 nM ouabain (blocks nearly all α(1)- and α(2)-pumps) was toxic to most cultured hASMCs. Treatment with 10 nM ouabain (72 h), however, increased NCX1 and sarco(endo)plasmic reticulum Ca(2+)-ATPase expression and augmented ATP (10 µM)-induced SR Ca(2+) release in 0 Ca(2+), ouabain-free media, and Ca(2+) influx after external Ca(2+) restoration. The latter was likely mediated primarily by ROCs and store-operated Ca(2+) channels. These hASMC protein expression and Ca(2+) signaling changes are comparable with previous observations on myocytes isolated from arteries of many rat hypertension models. We conclude that the same structurally and functionally coupled mechanisms (α(2)-Na(+) pumps, NCX1, ROCs, and the SR) regulate Ca(2+) homeostasis and signaling in hASMCs and rodent ASMCs. These ouabain/endogenous ouabain-modulated mechanisms underlie the whole body autoregulation associated with increased vascular resistance and elevation of BP in human, salt-sensitive hypertension.
Asunto(s)
Señalización del Calcio/efectos de los fármacos , Músculo Liso Vascular/efectos de los fármacos , Miocitos del Músculo Liso/efectos de los fármacos , Ouabaína/farmacología , Cloruro de Sodio/farmacología , Intercambiador de Sodio-Calcio/efectos de los fármacos , Resistencia Vascular/efectos de los fármacos , Adolescente , Adulto , Anciano , Animales , Presión Sanguínea/efectos de los fármacos , Western Blotting , Cardenólidos/metabolismo , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Forma de la Célula/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Relación Dosis-Respuesta a Droga , Femenino , Homeostasis , Humanos , Hipertensión/inducido químicamente , Hipertensión/metabolismo , Hipertensión/fisiopatología , Inmunohistoquímica , Receptores de Inositol 1,4,5-Trifosfato/efectos de los fármacos , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Masculino , Arterias Mamarias/efectos de los fármacos , Arterias Mamarias/metabolismo , Ratones , Ratones Endogámicos C57BL , Microscopía Fluorescente , Persona de Mediana Edad , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/fisiopatología , Miocitos del Músculo Liso/metabolismo , Ratas , Saponinas/metabolismo , Retículo Sarcoplasmático/efectos de los fármacos , Retículo Sarcoplasmático/metabolismo , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismo , Cloruro de Sodio/toxicidad , Intercambiador de Sodio-Calcio/metabolismo , ATPasa Intercambiadora de Sodio-Potasio/antagonistas & inhibidores , ATPasa Intercambiadora de Sodio-Potasio/metabolismo , Canales Catiónicos TRPC/efectos de los fármacos , Canales Catiónicos TRPC/metabolismo , Factores de Tiempo , Regulación hacia Arriba , Adulto JovenRESUMEN
Pharmacologic modification of cellular calcium handling recently moved into focus as an alternative for prevention and treatment of ventricular tachyarrhythmias. Calcium overload and spontaneous calcium release from the sarcoplasmatic reticulum are regarded as possible initiations of early and delayed afterdepolarization thereby triggering ventricular arrhythmias. In chronic heart failure, calcium overload is more likely to occur compared with healthy hearts, which is one explantation for the increased vulnerability in this condition. L-type calcium channel, sodium-calcium-exchanger (NCX), and ryanodine receptor are crucial for calcium homeostasis and therefore represent potential targets for antiarrhythmic drug therapy. Experimental studies have proven beneficial effects for all these three mechanisms in prevention and suppression of tachyarrhythmias. However, clinical data is mainly available for the L-type calcium channel inhibitor verapamil. Therefore, it is still a long way to clinical employment of drugs modifying cellular calcium handling for antiarrhythmic therapy.