RESUMEN
Impaired endothelium-dependent vasodilation has been suggested to be a key component of coronary microvascular dysfunction (CMD). A better understanding of endothelial pathways involved in vasodilation in human arterioles may provide new insight into the mechanisms of CMD. The goal of this study is to investigate the role of TRPV4, NOX4, and their interaction in human arterioles and examine the underlying mechanisms. Arterioles were freshly isolated from adipose and heart tissues obtained from 71 patients without coronary artery disease, and vascular reactivity was studied by videomicroscopy. In human adipose arterioles (HAA), ACh-induced dilation was significantly reduced by TRPV4 inhibitor HC067047 and by NOX 1/4 inhibitor GKT137831, but GKT137831 did not further affect the dilation in the presence of TRPV4 inhibitors. GKT137831 also inhibited TRPV4 agonist GSK1016790A-induced dilation in HAA and human coronary arterioles (HCA). NOX4 transcripts and proteins were detected in endothelial cells of HAA and HCA. Using fura-2 imaging, GKT137831 significantly reduced GSK1016790A-induced Ca2+ influx in the primary culture of endothelial cells and TRPV4-WT-overexpressing human coronary artery endothelial cells (HCAEC). However, GKT137831 did not affect TRPV4-mediated Ca2+ influx in non-phosphorylatable TRPV4-S823A/S824A-overexpressing HCAEC. In addition, treatment of HCAEC with GKT137831 decreased the phosphorylation level of Ser824 in TRPV4. Finally, proximity ligation assay (PLA) revealed co-localization of NOX4 and TRPV4 proteins. In conclusion, both TRPV4 and NOX4 contribute to ACh-induced dilation in human arterioles from patients without coronary artery disease. NOX4 increases TRPV4 phosphorylation in endothelial cells, which in turn enhances TRPV4-mediated Ca2+ entry and subsequent endothelium-dependent dilation in human arterioles.
Asunto(s)
Enfermedad de la Arteria Coronaria , Vasodilatación , Arteriolas/metabolismo , Enfermedad de la Arteria Coronaria/metabolismo , Células Endoteliales/metabolismo , Endotelio Vascular/metabolismo , Humanos , NADPH Oxidasa 4/metabolismo , Fosforilación , Canales Catiónicos TRPV , Vasodilatación/fisiologíaRESUMEN
Adaptor protein p66Shc is overexpressed in smooth muscle cells of renal resistance vessels of hypertensive salt-sensitive rats and is involved in the regulation of renal vascular tone. We applied 2-photon laser scanning fluorescence microscopy to analyze spontaneous dynamic fluctuations in intracellular calcium concentrations ([Ca2+]i) in smooth muscle cells embedded in the walls of freshly isolated renal resistance arteries. The amplitude, number of events, and frequency of spontaneous [Ca2+]i oscillations triggered by endogenously released endothelin-1 were recorded in smooth muscle cells of the renal arteries. Endothelin receptor A antagonist BQ123 dramatically reduced the amplitude and frequency of spontaneous Ca2+ events, producing marked inhibition of renal vessels spontaneous motion. Spontaneous Ca2+ fluctuations in smooth muscle cells of p66Shc knockout (p66ShcKO) rats had significantly higher amplitude than in control rats. The frequency of spontaneous [Ca2+]i oscillations did not change in p66ShcKO rats, suggesting that p66Shc expression did not affect endothelin-1 release from resident endothelial cells. Acute application of endothelin-1 revealed significantly elevated production of the total [Ca2+]i in p66ShcKO rats. Spontaneous cytosolic Ca2+ oscillations in smooth muscle cells of renal vessels mediate their spontaneous motion via the endothelin-1/endothelin receptor A pathway. p66Shc decreases the amplitude of individual changes in [Ca2+]i, which mitigates the spontaneous motion of renal vessels.-Palygin, O., Miller, B. S., Nishijima, Y., Zhang, D. X., Staruschenko, A., Sorokin, A. Endothelin receptor A and p66Shc regulate spontaneous Ca2+ oscillations in smooth muscle cells controlling renal arterial spontaneous motion.
Asunto(s)
Calcio/metabolismo , Hipertensión/fisiopatología , Músculo Liso Vascular/fisiología , Receptor de Endotelina A/metabolismo , Arteria Renal/fisiología , Proteína Transformadora 1 que Contiene Dominios de Homología 2 de Src/metabolismo , Resistencia Vascular , Animales , Células Cultivadas , Endotelina-1/metabolismo , Hipertensión/metabolismo , Masculino , Músculo Liso Vascular/citología , Ratas , Ratas Endogámicas Dahl , Arteria Renal/citologíaRESUMEN
Transient receptor potential vanilloid 4 (TRPV4) is a Ca2+-permeable channel of the transient receptor potential (TRP) superfamily activated by diverse stimuli, including warm temperature, mechanical forces, and lipid mediators such as arachidonic acid (AA) and its metabolites. This activation is tightly regulated by protein phosphorylation carried out by various serine/threonine or tyrosine kinases. It remains poorly understood how phosphorylation differentially regulates TRPV4 activation in response to different stimuli. We investigated how TRPV4 activation by AA, an important signaling process in the dilation of coronary arterioles, is affected by protein kinase A (PKA)-mediated phosphorylation at Ser-824. Wildtype and mutant TRPV4 channels were expressed in human coronary artery endothelial cells (HCAECs). AA-induced TRPV4 activation was blunted in the S824A mutant but was enhanced in the phosphomimetic S824E mutant, whereas the channel activation by the synthetic agonist GSK1016790A was not affected. The low level of basal phosphorylation at Ser-824 was robustly increased by the redox signaling molecule hydrogen peroxide (H2O2). The H2O2-induced phosphorylation was accompanied by an enhanced channel activation by AA, and this enhanced response was largely abolished by PKA inhibition or S824A mutation. We further identified a potential structural context dependence of Ser-824 phosphorylation-mediated TRPV4 regulation involving an interplay between AA binding and the possible phosphorylation-induced rearrangements of the C-terminal helix bearing Ser-824. These results provide insight into how phosphorylation specifically regulates TRPV4 activation. Redox-mediated TRPV4 phosphorylation may contribute to pathologies associated with enhanced TRPV4 activity in endothelial and other systems.
Asunto(s)
Canales Catiónicos TRPV/metabolismo , Canales Catiónicos TRPV/fisiología , Ácido Araquidónico/metabolismo , Canales de Calcio/metabolismo , Células Cultivadas , Vasos Coronarios/metabolismo , Cristalografía por Rayos X , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Células Endoteliales/metabolismo , Humanos , Peróxido de Hidrógeno/metabolismo , Fosforilación , Transducción de SeñalRESUMEN
RATIONALE: Hydrogen peroxide (H2O2) regulates vascular tone in the human microcirculation under physiological and pathophysiological conditions. It dilates arterioles by activating large-conductance Ca2+-activated K+ channels in subjects with coronary artery disease (CAD), but its mechanisms of action in subjects without CAD (non-CAD) when compared with those with CAD remain unknown. OBJECTIVE: We hypothesize that H2O2-elicited dilation involves different K+ channels in non-CAD versus CAD, resulting in an altered capacity for vasodilation during disease. METHODS AND RESULTS: H2O2 induced endothelium-independent vasodilation in non-CAD adipose arterioles, which was reduced by paxilline, a large-conductance Ca2+-activated K+ channel blocker, and by 4-aminopyridine, a voltage-gated K+ (KV) channel blocker. Assays of mRNA transcripts, protein expression, and subcellular localization revealed that KV1.5 is the major KV1 channel expressed in vascular smooth muscle cells and is abundantly localized on the plasma membrane. The selective KV1.5 blocker diphenylphosphine oxide-1 and the KV1.3/1.5 blocker 5-(4-phenylbutoxy)psoralen reduced H2O2-elicited dilation to a similar extent as 4-aminopyridine, but the selective KV1.3 blocker phenoxyalkoxypsoralen-1 was without effect. In arterioles from CAD subjects, H2O2-induced dilation was significantly reduced, and this dilation was inhibited by paxilline but not by 4-aminopyridine, diphenylphosphine oxide-1, or 5-(4-phenylbutoxy)psoralen. KV1.5 cell membrane localization and diphenylphosphine oxide-1-sensitive K+ currents were markedly reduced in isolated vascular smooth muscle cells from CAD arterioles, although mRNA or total cellular protein expression was largely unchanged. CONCLUSIONS: In human arterioles, H2O2-induced dilation is impaired in CAD, which is associated with a transition from a combined large-conductance Ca2+-activated K+- and KV (KV1.5)-mediated vasodilation toward a large-conductance Ca2+-activated K+-predominant mechanism of dilation. Loss of KV1.5 vasomotor function may play an important role in microvascular dysfunction in CAD or other vascular diseases.
Asunto(s)
Arteriolas/fisiología , Enfermedad de la Arteria Coronaria/fisiopatología , Peróxido de Hidrógeno/farmacología , Canal de Potasio Kv1.5/fisiología , Vasodilatación/fisiología , Adulto , Anciano , Arteriolas/efectos de los fármacos , Arteriolas/patología , Células Cultivadas , Enfermedad de la Arteria Coronaria/patología , Vasos Coronarios/efectos de los fármacos , Vasos Coronarios/patología , Vasos Coronarios/fisiología , Femenino , Células HEK293 , Humanos , Canal de Potasio Kv1.5/antagonistas & inhibidores , Masculino , Persona de Mediana Edad , Músculo Liso Vascular/citología , Músculo Liso Vascular/efectos de los fármacos , Músculo Liso Vascular/fisiología , Vasodilatación/efectos de los fármacosRESUMEN
OBJECTIVES: KV channels are important regulators of vascular tone, but the identity of specific KV channels involved and their regulation in disease remain less well understood. We determined the expression of KV 1 channel subunits and their role in cAMP-mediated dilation in coronary resistance arteries from subjects with and without CAD. METHODS: HCAs from patients with and without CAD were assessed for mRNA and protein expression of KV 1 channel subunits with molecular techniques and for vasodilator response with isolated arterial myography. RESULTS: Assays of mRNA transcripts, membrane protein expression, and vascular cell-specific localization revealed abundant expression of KV 1.5 in vascular smooth muscle cells of non-CAD HCAs. Isoproterenol and forskolin, two distinct cAMP-mediated vasodilators, induced potent dilation of non-CAD arterioles, which was inhibited by both the general KV blocker 4-AP and the selective KV 1.5 blocker DPO-1. The cAMP-mediated dilation was reduced in CAD and was accompanied by a loss of or reduced contribution of 4-AP-sensitive KV channels. CONCLUSIONS: KV 1.5, as a major 4-AP-sensitive KV 1 channel expressed in coronary VSMCs, mediates cAMP-mediated dilation in non-CAD arterioles. The cAMP-mediated dilation is reduced in CAD coronary arterioles, which is associated with impaired 4-AP-sensitive KV channel function.
Asunto(s)
Vasos Coronarios/química , Canales de Potasio con Entrada de Voltaje/metabolismo , Vasodilatación/efectos de los fármacos , Arteriolas/fisiología , Enfermedades Cardiovasculares/etiología , Estudios de Casos y Controles , AMP Cíclico/fisiología , Humanos , Subunidades de Proteína , ARN Mensajero/análisisRESUMEN
Decreased nitric oxide (NO) bioavailability underlies a number of cardiovascular pathologies, including hypertension. The shear stress exerted by flowing blood is the main determinant of NO release. Rap1 promotes integrin- and cadherin-mediated signaling. Here, we show that Rap1 is a critical regulator of NO production and endothelial function. Rap1 deficiency in murine endothelium attenuates NO production and diminishes NO-dependent vasodilation, leading to endothelial dysfunction and hypertension, without deleterious effects on vessel integrity. Mechanistically, Rap1 is activated by shear stress, promotes the formation of the endothelial mechanosensing complex-comprised of PECAM-1, VE-cadherin and VEGFR2- and downstream signaling to NO production. Our study establishes a novel paradigm for Rap1 as a regulator of mechanotransduction.
Asunto(s)
Endotelio/metabolismo , Mecanotransducción Celular , Óxido Nítrico/metabolismo , Proteínas de Unión al GTP rap1/metabolismo , Animales , Presión Sanguínea , Permeabilidad Capilar/genética , Humanos , Hipertensión/genética , Hipertensión/metabolismo , Hipertensión/fisiopatología , Hipertrofia Ventricular Izquierda/genética , Hipertrofia Ventricular Izquierda/metabolismo , Hipertrofia Ventricular Izquierda/fisiopatología , Masculino , Ratones , Ratones Noqueados , Modelos Biológicos , Óxido Nítrico Sintasa de Tipo III/metabolismo , Especificidad de Órganos/genética , Transducción de Señal , Vasodilatación/genética , Proteínas de Unión al GTP rap1/genéticaRESUMEN
INTRODUCTION: Bisphosphonates, including ibandronate, are used in the prevention and treatment of osteoporosis. METHODS AND RESULTS: We report a case of suspected ibandronate-associated arrhythmia, following a single dose of ibandronate in a 55-year-old female. ECG at presentation revealed frequent ectopy and QT/QTc interval prolongation; at follow-up 9 months later the QT/QTc intervals were normalized. Proarrhythmic potential of ibandronate was assessed with a combination of in vivo and in vitro approaches in canines and canine ventricular myocytes. We observed late onset in vivo repolarization instability after ibandronate treatment. Myocytes superfused with ibandronate exhibited action potential duration (APD) prolongation and variability, increased early afterdepolarizations (EADs) and reduced Ito (P < 0.05), with no change in IKr . Ibandronate-induced APD changes and EADs were prevented by inhibition of intracellular calcium cycling. Ibandronate increased sarcoplasmic reticulum calcium load; during washout there was an increase in calcium spark frequency and spontaneous calcium waves. Computational modeling was used to examine the observed effects of ibandronate. While reductions in Ito alone had modest effects on APD, when combined with altered RyR inactivation kinetics, the model predicted effects on APD and SR Ca(2+) load consistent with observed experimental results. CONCLUSION: Ibandronate may increase the susceptibility to ventricular ectopy and arrhythmias. Collectively these data suggest that reduced Ito combined with abnormal RyR calcium handling may result in a previously unrecognized form of drug-induced proarrhythmia.
Asunto(s)
Conservadores de la Densidad Ósea/efectos adversos , Difosfonatos/efectos adversos , Fibrilación Ventricular/inducido químicamente , Fibrilación Ventricular/diagnóstico , Animales , Señalización del Calcio/efectos de los fármacos , Señalización del Calcio/fisiología , Células Cultivadas , Perros , Femenino , Humanos , Ácido Ibandrónico , Masculino , Persona de Mediana Edad , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/fisiología , Fibrilación Ventricular/fisiopatologíaRESUMEN
The GTP-binding protein Rac regulates diverse cellular functions including activation of NADPH oxidase, a major source of superoxide production (O(2)(·-)). Rac1-mediated NADPH oxidase activation is increased after myocardial infarction (MI) and heart failure both in animals and humans; however, the impact of increased myocardial Rac on impending ischemia-reperfusion (I/R) is unknown. A novel transgenic mouse model with cardiac-specific overexpression of constitutively active mutant form of Zea maize Rac D (ZmRacD) gene has been reported with increased myocardial Rac-GTPase activity and O(2)(·-) generation. The goal of the present study was to determine signaling pathways related to increased myocardial ZmRacD and to what extent hearts with increased ZmRacD proteins are susceptible to I/R injury. The effect of myocardial I/R was examined in young adult wild-type (WT) and ZmRacD transgenic (TG) mice. In vitro reversible myocardial I/R for postischemic cardiac function and in vivo regional myocardial I/R for MI were performed. Following 20-min global ischemia and 45-min reperfusion, postischemic cardiac contractile function and heart rate were significantly reduced in TG hearts compared with WT hearts. Importantly, acute regional myocardial I/R (30-min ischemia and 24-h reperfusion) caused significantly larger MI in TG mice compared with WT mice. Western blot analysis of cardiac homogenates revealed that increased myocardial ZmRacD gene expression is associated with concomitant increased levels of NADPH oxidase subunit gp91(phox), O(2)(·-), and P(21)-activated kinase. Thus these findings provide direct evidence that increased levels of active myocardial Rac renders the heart susceptible to increased postischemic contractile dysfunction and MI following acute I/R.
Asunto(s)
Daño por Reperfusión Miocárdica/enzimología , Aturdimiento Miocárdico/enzimología , Miocitos Cardíacos/enzimología , Proteínas de Unión al GTP rac/metabolismo , Animales , Western Blotting , Modelos Animales de Enfermedad , Genotipo , Frecuencia Cardíaca , Glicoproteínas de Membrana/metabolismo , Ratones , Ratones Transgénicos , Contracción Miocárdica , Daño por Reperfusión Miocárdica/genética , Daño por Reperfusión Miocárdica/patología , Daño por Reperfusión Miocárdica/fisiopatología , Aturdimiento Miocárdico/genética , Aturdimiento Miocárdico/patología , Aturdimiento Miocárdico/fisiopatología , Miocitos Cardíacos/patología , NADPH Oxidasa 2 , NADPH Oxidasas/metabolismo , Fenotipo , Transducción de Señal , Superóxidos/metabolismo , Factores de Tiempo , Regulación hacia Arriba , Quinasas p21 Activadas/metabolismo , Proteínas de Unión al GTP rac/genéticaRESUMEN
Oxidative stress has been implicated in the pathogenesis of heart failure and atrial fibrillation and can result in increased peroxynitrite production in the myocardium. Atrial and ventricular canine cardiac myocytes were superfused with 3-morpholinosydnonimine-N-ethylcarbamide (SIN-1), a peroxynitrite donor, to evaluate the acute electrophysiologic effects of peroxynitrite. Perforated whole-cell patch clamp techniques were used to record action potentials. SIN-1 (200 µM) increased the action potential duration (APD) in atrial and ventricular myocytes; however, in the atria, APD prolongation was rate independent, whereas in the ventricle APD, prolongation was rate dependent. In addition to prolongation of the action potential, beat-to-beat variability of repolarization was significantly increased in ventricular but not in atrial myocytes. We examined the contribution of intracellular calcium cycling to the effects of SIN-1 by treating myocytes with the SERCA blocker, thapsigargin (5-10 µM). Inhibition of calcium cycling prevented APD prolongation in the atrial and ventricular myocytes, and prevented the SIN-1-induced increase in ventricular beat-to-beat APD variability. Collectively, these data demonstrate that peroxynitrite affects atrial and ventricular electrophysiology differentially. A detailed understanding of oxidative modulation of electrophysiology in specific chambers is critical to optimize therapeutic approaches for cardiac diseases.
Asunto(s)
Potenciales de Acción/fisiología , Función Atrial/fisiología , Molsidomina/análogos & derivados , Miocitos Cardíacos/efectos de los fármacos , Donantes de Óxido Nítrico/farmacología , Función Ventricular/fisiología , Potenciales de Acción/efectos de los fármacos , Animales , Perros , Inhibidores Enzimáticos/farmacología , Femenino , Masculino , Molsidomina/farmacología , Tapsigargina/farmacologíaRESUMEN
There is emerging evidence that treatment with thyroid hormone (TH) can improve postischemic cardiac function. 3,5-Diiodothyropropionic acid (DITPA), a TH analog, has been proposed to be a safer therapeutic agent than TH because of its negligible effects on cardiac metabolism and heart rate. However, conflicting results have been reported for the cardiac effects of DITPA. Importantly, recent clinical trials demonstrated no symptomatic benefit in patients with DITPA despite some improved hemodynamic and metabolic parameters. To address these issues, dose-dependent effects of DITPA were investigated in mice for baseline cardiovascular effects and postischemic myocardial function and/or salvage. Mice were treated with subcutaneous DITPA at 0.937, 1.875, 3.75, or 7.5 mg·kg(-1)·day(-1) for 7 days, and the results were compared with untreated mice for ex vivo and/or in vivo myocardial ischemia-reperfusion (I/R). DITPA had no effects on baseline body temperature, body weight, or heart rate; however, it mildly increased blood pressure. In isolated hearts, baseline contractile function was significantly impaired in DITPA-pretreated mice; however, postischemic recovery was comparable between untreated and DITPA-treated groups. In vivo baseline cardiac parameters were significantly affected by DITPA, with increased ventricular dimensions and decreased contractile function. Importantly, DITPA-treated mice demonstrated high prevalence of fatal cardiac rhythm abnormalities during in vivo ischemia and/or reperfusion. There were no improvements in myocardial infarction and postischemic fractional shortening with DITPA. Myocardial sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA), phospholamban (PLB), and heat shock protein (HSP) levels remained unchanged with DITPA treatment. Thus DITPA administration impairs baseline cardiac parameters in mice and can be fatal during in vivo acute myocardial I/R.
Asunto(s)
Diyodotironinas/toxicidad , Corazón/efectos de los fármacos , Daño por Reperfusión Miocárdica/mortalidad , Propionatos/toxicidad , Animales , Arritmias Cardíacas/inducido químicamente , Arritmias Cardíacas/fisiopatología , Presión Sanguínea/efectos de los fármacos , Western Blotting , Cardiotónicos/farmacología , Interpretación Estadística de Datos , Relación Dosis-Respuesta a Droga , Ecocardiografía , Electrocardiografía/efectos de los fármacos , Técnicas In Vitro , Masculino , Ratones , Ratones Endogámicos C57BL , Infarto del Miocardio/patología , Simpatomiméticos/farmacología , Tiroxina/farmacología , Triyodotironina/farmacología , Función Ventricular Izquierda/efectos de los fármacosRESUMEN
Glucose uptake across the sarcolemma is regulated by a family of membrane proteins called glucose transporters (GLUTs), which includes GLUT4 (the major cardiac isoform) and GLUT12 (a novel, second insulin-sensitive isoform). Potential regional patterns in glucose transport across the cardiac chambers have not been examined; thus, we hypothesized that insulin-responsive GLUT4 and -12 protein and gene expression would be chamber specific in healthy subjects and during chronic heart failure (HF). Using a canine model of tachypacing-induced, progressive, chronic HF, total GLUT protein and messenger RNA in both ventricles and atria (free wall and appendage) were investigated by immunoblotting and real-time PCR. In controls, GLUT4, but not GLUT12, protein content was significantly higher in the atria compared with the ventricles, with the highest content in the right atrium (RA; P < 0.001). GLUT4 and GLUT12 mRNA levels were similar across the cardiac chambers. During chronic HF, GLUT4 and GLUT12 protein content was highest in the left ventricle (LV; by 2.5- and 4.2-fold, respectively, P < 0.01), with a concomitant increase in GLUT4 and GLUT12 mRNA (P < 0.001). GLUT4, but not GLUT12, protein content was decreased in RA during chronic HF (P = 0.001). In conclusion, GLUT4 protein was differentially expressed across the chambers in the healthy heart, and this regional pattern was reversed during HF. Our data suggest that LV was the primary site dependent on both GLUT4 and GLUT12 during chronic HF. In addition, the paradoxical decrease in GLUT4 content in RA may induce perturbations in atrial energy production during chronic HF.
Asunto(s)
Cardiomiopatía Dilatada/metabolismo , Proteínas Facilitadoras del Transporte de la Glucosa/metabolismo , Insuficiencia Cardíaca/metabolismo , Insulina/metabolismo , Miocardio/metabolismo , Animales , Función del Atrio Izquierdo , Western Blotting , Estimulación Cardíaca Artificial , Cardiomiopatía Dilatada/etiología , Cardiomiopatía Dilatada/genética , Cardiomiopatía Dilatada/fisiopatología , Enfermedad Crónica , Modelos Animales de Enfermedad , Perros , Proteínas Facilitadoras del Transporte de la Glucosa/genética , Transportador de Glucosa de Tipo 4/metabolismo , Atrios Cardíacos/metabolismo , Atrios Cardíacos/fisiopatología , Insuficiencia Cardíaca/etiología , Insuficiencia Cardíaca/genética , Insuficiencia Cardíaca/fisiopatología , Ventrículos Cardíacos/metabolismo , Ventrículos Cardíacos/fisiopatología , ARN Mensajero/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Función Ventricular IzquierdaRESUMEN
[This corrects the article DOI: 10.3389/fcell.2021.687598.].
RESUMEN
BACKGROUND AND PURPOSE: The TRPV cation channels have emerged as important regulators of vascular tone. TRPV1 channels and endothelin-1 are independently associated with the pathophysiology of coronary vasospasm, but the relationship between their vasomotor functions remains unclear. We characterized the vasomotor function of TRPV1 channels in human arterioles and investigated regulation of their vasomotor function by endothelin-1. EXPERIMENTAL APPROACH: Human arterioles (mainly from adipose tissue) were threaded on two metal wires, equilibrated in a physiological buffer at 37°C and exposed to increasing concentrations of capsaicin, with or without SB366791 (TRPV1-selective inhibitor) or GF109203X (PKC-selective inhibitor). Some arterioles were pre-constricted with endothelin-1 or phenylephrine or high potassium buffer. TRPV1 mRNA and protein expression in human arteries were also assessed. KEY RESULTS: TRPV1 transcripts and proteins were detected in human resistance arteries. Capsaicin (1 µM) induced concentration-dependent constriction of endothelium-intact and endothelium-denuded human adipose arterioles (HAA), which was significantly inhibited by SB366791. Pre-constriction of HAA with endothelin-1, but not high potassium buffer or phenylephrine, significantly potentiated capsaicin (0.1 µM)-induced constriction. GF109203X significantly inhibited potentiation of capsaicin-induced constriction by endothelin-1. CONCLUSION AND IMPLICATIONS: TRPV1 channels are expressed in the human vasculature and affect vascular tone of human arterioles on activation. Their vasomotor function is modulated by endothelin-1, mediated in part by PKC. These findings reveal a novel interplay between endothelin-1 signalling and TRPV1 channels in human VSMC, adding to our understanding of the ion channel mechanisms that regulate human arteriolar tone and may also contribute to the pathophysiology of coronary vasospasm.
Asunto(s)
Endotelina-1 , Vasoconstricción , Tejido Adiposo , Arteriolas , Capsaicina/farmacología , Humanos , Proteína Quinasa C , Canales Catiónicos TRPVRESUMEN
Small GTPase Rap1 plays a prominent role in endothelial cell (EC) homeostasis by promoting NO release. Endothelial deletion of the two highly homologous Rap1 isoforms, Rap1A and Rap1B, leads to endothelial dysfunction ex vivo and hypertension in vivo. Mechanistically, we showed that Rap1B promotes NO release in response to shear flow by promoting mechanosensing complex formation involving VEGFR2 and Akt activation. However, the specific contribution of the Rap1A isoform to NO release and the underlying molecular mechanisms through which the two Rap1 isoforms control endothelial function are unknown. Here, we demonstrate that endothelial dysfunction resulting from knockout of both Rap1A and Rap1B isoforms is ameliorated by exogenous L-Arg administration to rescue NO-dependent vasorelaxation and blood pressure. We confirmed that Rap1B is rapidly activated in response to agonists that trigger eNOS activation, and its deletion in ECs attenuates eNOS activation, as detected by decreased Ser1177 phosphorylation. Somewhat surprising was the finding that EC deletion of Rap1A does not lead to impaired agonist-induced vasorelaxation ex vivo. Mechanistically, the deletion of Rap1A led to elevated eNOS phosphorylation both at the inhibitory, T495, and the activating Ser1177 residues. These findings indicate that the two Rap1 isoforms act via distinct signaling pathways: while Rap1B directly positively regulates eNOS activation, Rap1A prevents negative regulation of eNOS. Notably, the combined deficiency of Rap1A and Rap1B has a severe effect on eNOS activity and NO release with an in vivo impact on endothelial function and vascular homeostasis.
RESUMEN
Treating cancer patients with chemotherapeutics, such as doxorubicin (Dox), cause dilated cardiomyopathy and congestive heart failure because of oxidative stress. On the other hand, heat shock factor-1 (HSF-1), a transcription factor for heat shock proteins (Hsps), is also known to be activated in response to oxidative stress. However, the possible role of HSF-1 activation and the resultant Hsp25 in chemotherapeutic-induced heart failure has not been investigated. Using HSF-1 wild-type (HSF-1(+/+)) and knock-out (HSF-1(-/-)) mice, we tested the hypothesis that activation of HSF-1 plays a role in the development of Dox-induced heart failure. Higher levels of Hsp25 and its phosphorylated forms were found in the failing hearts of Dox-treated HSF-1(+/+) mice. More than twofold increase in Hsp25 mRNA level was found in Dox-treated hearts. Proteomic analysis showed that there is accumulation and aggregation of Hsp25 in Dox-treated failing hearts. Additionally, Hsp25 was found to coimmunoprecipitate with p53 and vice versa. Further studies indicated that the Dox-induced higher levels of Hsp25 transactivated p53 leading to higher levels of the pro-apoptotic protein Bax, but other p53-related proteins remained unaltered. Moreover, HSF-1(-/-) mice showed significantly reduced Dox-induced heart failure and higher survival rate, and there was no change in Bax upon treating with Dox in HSF-1(-/-) mice. From these results we propose a novel mechanism for Dox-induced heart failure: increased expression of Hsp25 because of oxidant-induced activation of HSF-1 transactivates p53 to increase Bax levels, which leads to heart failure.
Asunto(s)
Antibióticos Antineoplásicos/efectos adversos , Proteínas de Unión al ADN/fisiología , Doxorrubicina/efectos adversos , Insuficiencia Cardíaca/inducido químicamente , Insuficiencia Cardíaca/fisiopatología , Factores de Transcripción/fisiología , Animales , Proteínas de Unión al ADN/genética , Modelos Animales de Enfermedad , Insuficiencia Cardíaca/metabolismo , Factores de Transcripción del Choque Térmico , Proteínas de Choque Térmico/metabolismo , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Chaperonas Moleculares , Proteínas de Neoplasias/metabolismo , Estrés Oxidativo/fisiología , Factores de Transcripción/genética , Proteína p53 Supresora de Tumor/metabolismo , Proteína X Asociada a bcl-2/metabolismoRESUMEN
Since omega-3 polyunsaturated fatty acids (n-3 PUFAs) can alter ventricular myocyte calcium handling, these fatty acids could adversely affect cardiac contractile function, particularly following myocardial infarction. Therefore, 4 wk after myocardial infarction, dogs were randomly assigned to either placebo (corn oil, 1 g/day, n = 16) or n-3 PUFAs supplement [docosahexaenoic acid (DHA) + eicosapentaenoic acid (EPA) ethyl esters; 1, 2, or 4 g/day; n = 7, 8, and 12, respectively] groups. In vivo, ventricular function was evaluated by echocardiography before and after 3 mo of treatment. At the end of the 3-mo period, hearts were removed and in vitro function was evaluated using right ventricular trabeculae and isolated left ventricular myocytes. The treatment elicited significant (P < 0.0001) dose-dependent increases (16.4-fold increase with 4 g/day) in left ventricular tissue and red blood cell n-3 PUFA levels (EPA + DHA, placebo, 0.42 +/- 0.04; 1 g/day, 3.02 +/- 0.23; 2 g/day, 3.63 +/- 0.17; and 4 g/day, 6.97 +/- 0.33%). Regardless of the dose, n-3 PUFA treatment did not alter ventricular function in the intact animal (e.g., 4 g/day, fractional shortening: pre, 42.9 +/- 1.6 vs. post, 40.1 +/- 1.7%; placebo: pre, 39.2 +/- 1.3 vs. post, 38.4 +/- 1.6%). The developed force per cross-sectional area, changes in length- and frequency-dependent behavior in contractile force, and the inotropic response to beta-adrenoceptor activation were also similar for trabeculae obtained from placebo- or n-3 PUFA-treated dogs. Finally, calcium currents and calcium transients were the same in myocytes from n-3 PUFA- and placebo-treated dogs. Thus dietary n-3 PUFAs did not adversely alter either in vitro or in vivo ventricular contractile function in dogs with healed infarctions.
Asunto(s)
Ácidos Docosahexaenoicos/farmacología , Ácido Eicosapentaenoico/análogos & derivados , Ácidos Grasos Omega-3/farmacología , Infarto del Miocardio/fisiopatología , Función Ventricular Izquierda/efectos de los fármacos , Función Ventricular Izquierda/fisiología , Animales , Calcio/metabolismo , Suplementos Dietéticos , Modelos Animales de Enfermedad , Ácidos Docosahexaenoicos/administración & dosificación , Perros , Relación Dosis-Respuesta a Droga , Ácido Eicosapentaenoico/administración & dosificación , Ácido Eicosapentaenoico/farmacología , Ácidos Grasos/metabolismo , Ácidos Grasos Omega-3/administración & dosificación , Femenino , Ventrículos Cardíacos/diagnóstico por imagen , Masculino , Contracción Miocárdica/efectos de los fármacos , Contracción Miocárdica/fisiología , Miocardio/metabolismo , Miocardio/patología , Técnicas de Placa-Clamp , UltrasonografíaRESUMEN
Abnormal cardiac ryanodine receptor (RyR2) function is recognized as an important factor in the pathogenesis of heart failure (HF). However, the specific molecular causes underlying RyR2 defects in HF remain poorly understood. In the present study, we used a canine model of chronic HF to test the hypothesis that the HF-related alterations in RyR2 function are caused by posttranslational modification by reactive oxygen species generated in the failing heart. Experimental approaches included imaging of cytosolic ([Ca(2+)](c)) and sarcoplasmic reticulum (SR) luminal Ca(2+) ([Ca(2+)]SR) in isolated intact and permeabilized ventricular myocytes and single RyR2 channel recording using the planar lipid bilayer technique. The ratio of reduced to oxidized glutathione, as well as the level of free thiols on RyR2 decreased markedly in failing versus control hearts consistent with increased oxidative stress in HF. RyR2-mediated SR Ca(2+) leak was significantly enhanced in permeabilized myocytes, resulting in reduced [Ca(2+)](SR) in HF compared to control cells. Both SR Ca(2+) leak and [Ca(2+)](SR) were partially normalized by treating HF myocytes with reducing agents. Conversely, oxidizing agents accelerated SR Ca(2+) leak and decreased [Ca(2+)](SR) in cells from normal hearts. Moreover, exposure to antioxidants significantly improved intracellular Ca(2+)-handling parameters in intact HF myocytes. Single RyR2 channel activity was significantly higher in HF versus control because of increased sensitivity to activation by luminal Ca(2+) and was partially normalized by reducing agents through restoring luminal Ca(2+) sensitivity oxidation of control RyR2s enhanced their luminal Ca(2+) sensitivity, thus reproducing the HF phenotype. These findings suggest that redox modification contributes to abnormal function of RyR2s in HF, presenting a potential therapeutic target for treating HF.
Asunto(s)
Calcio/metabolismo , Insuficiencia Cardíaca/etiología , Insuficiencia Cardíaca/metabolismo , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , Retículo Sarcoplasmático/metabolismo , Animales , Enfermedad Crónica , Modelos Animales de Enfermedad , Perros , Insuficiencia Cardíaca/patología , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Oxidación-Reducción , Estrés Oxidativo/fisiología , Procesamiento Proteico-Postraduccional/fisiología , Especies Reactivas de Oxígeno/efectos adversos , Especies Reactivas de Oxígeno/metabolismo , Canal Liberador de Calcio Receptor de Rianodina/efectos adversos , Retículo Sarcoplasmático/patologíaRESUMEN
The goal of the present study was to assess how reduced SERCA2a expression affects in vivo myocardial ischemia/reperfusion (I/R) injury. We specifically wanted to determine to what extent hearts with reduced SERCA2a levels are susceptible to in vivo I/R injury. Therefore, we examined the effects of different ischemic periods on post-ischemic myocardial injury in wild-type (WT) and SERCA2a heterozygous knockout (SERCA2a(+/-)) mice expressing lower levels of SERCA2a pump in vivo. Following 20-min ischemia and 48-hour reperfusion, SERCA2a(+/-) mice developed significant myocardial infarction (MI) compared to negligible infarction in WT mice (14+/-3% vs. 3+/-1%, P<0.01); whereas following 30-min ischemia, the infarction was significantly larger in SERCA2a(+/-) mice compared to WT mice (49+/-5% vs. 37+/-3%, P<0.05). Further, echocardiographic analysis revealed worsened postischemic contractile function in SERCA2a(+/-) mice compared to WT mice. Thus, these findings demonstrate that maintaining optimal SERCA2a function is critical for myocardial protection from I/R injury and postischemic functional recovery.
Asunto(s)
Infarto del Miocardio/metabolismo , Infarto del Miocardio/patología , Daño por Reperfusión Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/patología , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/fisiología , Animales , Western Blotting , Ecocardiografía , Ratones , Ratones Noqueados , Infarto del Miocardio/genética , Daño por Reperfusión Miocárdica/genética , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/genéticaRESUMEN
While cardiac resynchronization therapy (CRT) has been shown to reduce morbidity and mortality in heart failure (HF) patients, the fundamental mechanisms for the efficacy of CRT are poorly understood. The lack of understanding of these basic mechanisms represents a significant barrier to our understanding of the pathogenesis of HF and potential recovery mechanisms. Our purpose was to determine cellular mechanisms for the observed improvement in chronic HF after CRT. We used a canine model of chronic nonischemic cardiomyopathy. After 15 months, dogs were randomized to continued RV tachypacing (untreated HF) or CRT for an additional 9 months. Six minute walk tests, echocardiograms, and electrocardiograms were done to assess the functional response to therapy. Left ventricular (LV) midmyocardial myocytes were isolated to study electrophysiology and intracellular calcium regulation. Compared to untreated HF, CRT improved HF-induced increases in LV volumes, diameters and mass (p<0.05). CRT reversed HF-induced prolongations in LV myocyte repolarization (p<0.05) and normalized HF-induced depolarization (p<0.03) of the resting membrane potential. CRT improved HF-induced reductions in calcium (p<0.05). CRT did not attenuate the HF-induced increases in LV interstitial fibrosis. Using a translational approach in a chronic HF model, CRT significantly improved LV structure; this was accompanied by improved LV myocyte electrophysiology and calcium regulation. The beneficial effects of CRT may be attributable, in part, to improved LV myocyte function.