RESUMEN
BACKGROUND: Flow-mediated dilation (FMD) of human conduit arteries is, in part, related to shear stress-induced release of endothelium-derived nitric oxide (NO). However, NO synthase inhibitors do not completely abolish this FMD-response. Recently, a cytochrome P450 (CYP) epoxygenase of the 2C family was linked to NO- and prostacyclin-independent relaxation of conduit arteries. We therefore evaluated the contribution of CYP 2C9 to FMD in humans. METHODS AND RESULTS: FMD of the radial artery was determined in 12 healthy volunteers by high-resolution ultrasound and analyzed before and after intra-arterial infusion of sulfaphenazole, a specific CYP 2C9 inhibitor, L-NMMA (NO synthase inhibitor) and co-infusion of both. Endothelium-independent vasodilation was characterized after intra-arterial infusion of SNP. FMD was reduced after sulfaphenazole (11.5+/-0.87% vs. 7.4+/-0.95%, p<0.01), after L-NMMA (6.0+/-0.71%; p<0.01), and after co-infusion 3.9+/-0.73% (p<0.05 vs. L-NMMA; p<0.01 vs. sulfaphenazole). Sulfaphenazole had no effect on endothelium-independent vasodilation. In patients with chronic heart failure, the portion of FMD blocked by sulfaphenazole was not affected. CYP 2C was detected by immunohistochemistry in radial artery samples obtained from patients undergoing coronary bypass surgery. CONCLUSIONS: FMD in human conductance arteries is reduced after inhibition of CYP 2C9, supporting the concept that CYP 2C metabolites contribute to endothelium-mediated vasodilation of peripheral conduit arteries in vivo. In patients with heart failure, the CYP-dependent FMD appears to be preserved.
Asunto(s)
Arterias/fisiología , Hidrocarburo de Aril Hidroxilasas/fisiología , Insuficiencia Cardíaca/fisiopatología , Vasodilatación/fisiología , Anciano , Antiinfecciosos/farmacología , Enfermedad Crónica , Citocromo P-450 CYP2C9 , Femenino , Hemorreología , Humanos , Inmunohistoquímica , Masculino , Flujo Sanguíneo Regional/fisiología , Sulfafenazol/farmacología , Vasodilatación/efectos de los fármacosRESUMEN
OBJECTIVE: Xanthine oxidase (XO), a major source of superoxide, has been implicated in endothelial dysfunction in atherosclerosis. Mechanisms, however, leading to endothelial XO activation remain poorly defined. We tested the effect of angiotensin II (Ang II) on endothelial XO and its relevance for endothelial dysfunction in patients with coronary disease. METHODS AND RESULTS: XO protein levels and XO-dependent superoxide production were determined in cultured endothelial cells in response to Ang II. In patients with coronary disease, endothelium-bound XO activity as determined by ESR spectroscopy and endothelium-dependent vasodilation were analyzed before and after 4 weeks of treatment with the AT1-receptor blocker losartan, the XO inhibitor allopurinol, or placebo. Ang II substantially increased endothelial XO protein levels and XO-dependent superoxide production in cultured endothelial cells, which was prevented by NAD(P)H-oxidase inhibition. In vivo, endothelium-bound XO activity was reduced by losartan and allopurinol, but not placebo therapy in patients with coronary disease. XO inhibition with oxypurinol improved endothelium-dependent vasodilation before, but not after losartan or allopurinol therapy. CONCLUSIONS: These findings suggest a novel mechanism whereby Ang II promotes endothelial oxidant stress, ie, by redox-sensitive XO activation. In patients with coronary disease, losartan therapy reduces endothelium-bound XO activity likely contributing to improved endothelial function.
Asunto(s)
Angiotensina II/farmacología , Enfermedad Coronaria/fisiopatología , Endotelio Vascular/fisiopatología , Xantina Oxidasa/metabolismo , Anciano , Alopurinol/farmacología , Bloqueadores del Receptor Tipo 1 de Angiotensina II/farmacología , Animales , Bovinos , Células Cultivadas , Circulación Coronaria , Enfermedad Coronaria/enzimología , Células Endoteliales/efectos de los fármacos , Células Endoteliales/metabolismo , Endotelio Vascular/enzimología , Activación Enzimática/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Femenino , Humanos , Losartán/farmacología , Masculino , Persona de Mediana Edad , NADPH Oxidasas/metabolismo , Oxipurinol/farmacología , Superóxidos/metabolismo , Vasodilatación/efectos de los fármacos , Xantina Oxidasa/antagonistas & inhibidoresRESUMEN
BACKGROUND: Statins may exert important pleiotropic effects, ie, improve endothelial function, independently of their impact on LDL cholesterol. In humans, however, pleiotropic effects of statins have never been unequivocally demonstrated because prolonged statin treatment always results in reduced LDL cholesterol levels. We therefore tested the hypothesis that similar reductions in LDL cholesterol with simvastatin and ezetimibe, a novel cholesterol absorption inhibitor, result in different effects on endothelial function. METHODS AND RESULTS: Twenty patients with chronic heart failure were randomized to 4 weeks of simvastatin (10 mg/d) or ezetimibe (10 mg/d) treatment. Flow-dependent dilation (FDD) of the radial artery was determined by high-resolution ultrasound before and after intra-arterial vitamin C to determine the portion of FDD inhibited by radicals (DeltaFDD-VC). Activity of extracellular superoxide dismutase, a major vascular antioxidant enzyme system, was determined after release from the endothelium by a heparin bolus injection. Endothelial progenitor cells were analyzed with an in vitro assay. Simvastatin and ezetimibe treatment reduced LDL cholesterol to a similar extent (15.6% versus 15.4%; P=NS), whereas changes in mevalonate, the product of HMG-CoA-reductase, differed between groups (Deltamevalonate-simvastatin, -1.04+/-0.62 versus Deltamevalonate-ezetimibe, 1.79+/-0.94 ng/mL; P<0.05 between groups). Importantly, FDD was markedly improved after simvastatin (10.5+/-0.6% versus 5.1+/-0.7%; P<0.01) but not after ezetimibe treatment (5.6+/-0.5% versus 5.8+/-0.6%; P=NS). DeltaFDD-VC was substantially reduced after simvastatin but not after ezetimibe treatment. Extracellular superoxide dismutase activity was increased by >100% (P<0.05) after simvastatin but not ezetimibe treatment. Simvastatin treatment increased the number of functionally active endothelial progenitor cells, whereas ezetimibe had no effect. CONCLUSIONS: Four weeks of simvastatin treatment improves endothelial function independently of LDL cholesterol lowering, at least in part by reducing oxidant stress. Simvastatin may thereby exert important pleiotropic effects in humans.
Asunto(s)
Azetidinas/farmacología , Endotelio Vascular/efectos de los fármacos , Lípidos/sangre , Simvastatina/farmacología , Anticolesterolemiantes/farmacología , Ácido Ascórbico/administración & dosificación , Ácido Ascórbico/farmacología , Azetidinas/administración & dosificación , Endotelio Vascular/citología , Endotelio Vascular/enzimología , Ezetimiba , Femenino , Células Madre Hematopoyéticas/citología , Humanos , Masculino , Persona de Mediana Edad , Arteria Radial/efectos de los fármacos , Arteria Radial/fisiología , Especies Reactivas de Oxígeno , Simvastatina/administración & dosificación , Superóxido Dismutasa/análisis , Vasodilatación/efectos de los fármacosRESUMEN
BACKGROUND: Accumulating evidence suggests a critical role for increased reactive oxygen species (ROS) production in left ventricular (LV) remodeling and dysfunction after myocardial infarction (MI). Increased expression of xanthine oxidase (XO), a major source of ROS, has recently been demonstrated in experimental and clinical heart failure; however, a potential role for LV remodeling processes remains unclear. We therefore studied the effect of long-term treatment with allopurinol, a potent XO inhibitor, on myocardial ROS production and LV remodeling and dysfunction after MI. METHODS AND RESULTS: Mice with extensive anterior MI (n=105) were randomized to treatment with either vehicle or allopurinol (20 mg x kg(-1) x d(-1) by gavage) for 4 weeks starting on day 1 after surgery. Infarct size was similar among the groups. XO expression and activity were markedly increased in the remote myocardium of mice after MI, as determined by electron spin resonance spectroscopy. Myocardial ROS production was increased after MI but markedly reduced after allopurinol treatment. Importantly, allopurinol treatment substantially attenuated LV cavity dilatation and dysfunction after MI, as assessed by echocardiography, and markedly reduced myocardial hypertrophy and interstitial fibrosis. CONCLUSIONS: The present study reveals a novel beneficial effect of treatment with allopurinol, ie, a marked attenuation of LV remodeling processes and dysfunction after experimental MI. Allopurinol treatment therefore represents a potential novel strategy to prevent LV remodeling and dysfunction after MI.
Asunto(s)
Alopurinol/uso terapéutico , Infarto del Miocardio/tratamiento farmacológico , Disfunción Ventricular Izquierda/prevención & control , Remodelación Ventricular/efectos de los fármacos , Xantina Oxidasa/antagonistas & inhibidores , Animales , Evaluación Preclínica de Medicamentos , Fibrosis , Ligadura , Masculino , Ratones , Ratones Endogámicos C57BL , Infarto del Miocardio/complicaciones , Infarto del Miocardio/patología , Estrés Oxidativo , Distribución Aleatoria , Especies Reactivas de Oxígeno , Superóxidos/metabolismo , Disfunción Ventricular Izquierda/etiología , Xantina Oxidasa/metabolismoRESUMEN
BACKGROUND: Endothelial nitric oxide (eNO) bioavailability is severely reduced after myocardial infarction (MI) and in heart failure. Statins enhance eNO availability by both increasing eNO production and reducing NO inactivation. We therefore studied the effect of statin treatment on eNO availability after MI and tested its role for endothelial progenitor cell mobilization, myocardial neovascularization, left ventricular (LV) dysfunction, remodeling, and survival after MI. METHODS AND RESULTS: Wild-type (WT) and eNO synthase (eNOS)-/- mice with extensive anterior MI were randomized to treatment with vehicle (V) or atorvastatin (Ator, 50 mg/kg QD by gavage) for 4 weeks starting on day 1 after MI. Ator markedly improved endothelium-dependent, NO-mediated vasorelaxation; mobilization of endothelial progenitor cells; and myocardial neovascularization of the infarct border in WT mice after MI while having no effect in eNOS-/- mice. LV dysfunction and interstitial fibrosis were markedly attenuated by Ator in WT mice, whereas no effect was observed in eNOS-/- mice after MI. Importantly, Ator significantly increased the survival rate during 4 weeks after MI in WT mice (Ator versus V, 80% versus 46%; P<0.01, n=75) but not in eNOS-/- mice (43% versus 48%; NS, n=42). CONCLUSIONS: These findings suggest that increased eNO availability is required for statin-induced improvement of endothelial progenitor cell mobilization, myocardial neovascularization, LV dysfunction, interstitial fibrosis, and survival after MI. eNO bioavailability after MI likely represents an important therapeutic target in heart failure after MI and mediates beneficial effects of statin treatment after MI.
Asunto(s)
Circulación Colateral/efectos de los fármacos , Células Endoteliales/efectos de los fármacos , Ácidos Heptanoicos/uso terapéutico , Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Células Madre Mesenquimatosas/efectos de los fármacos , Infarto del Miocardio/enzimología , Óxido Nítrico Sintasa/fisiología , Óxido Nítrico/fisiología , Pirroles/uso terapéutico , Función Ventricular Izquierda/efectos de los fármacos , Remodelación Ventricular/efectos de los fármacos , Animales , Atorvastatina , Disponibilidad Biológica , Capilares/patología , Células Cultivadas/efectos de los fármacos , Resistencia a Medicamentos/genética , Células Endoteliales/citología , Fibrosis , Insuficiencia Cardíaca/enzimología , Insuficiencia Cardíaca/etiología , Insuficiencia Cardíaca/fisiopatología , Ácidos Heptanoicos/farmacología , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , Masculino , Células Madre Mesenquimatosas/citología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Infarto del Miocardio/diagnóstico por imagen , Infarto del Miocardio/patología , Infarto del Miocardio/fisiopatología , Miocardio/patología , Óxido Nítrico/biosíntesis , Óxido Nítrico Sintasa/deficiencia , Óxido Nítrico Sintasa/genética , Óxido Nítrico Sintasa de Tipo II , Óxido Nítrico Sintasa de Tipo III , Pirroles/farmacología , Distribución Aleatoria , Ultrasonografía , Vasodilatación/efectos de los fármacos , Vasodilatación/fisiologíaRESUMEN
BACKGROUND: Increased inactivation of nitric oxide by superoxide (O2*-) contributes to endothelial dysfunction in patients with coronary disease (CAD). We therefore characterized the vascular activities of xanthine oxidase and NAD(P)H oxidase, 2 major O2*--producing enzyme systems, and their relationship with flow-dependent, endothelium-mediated vasodilation (FDD) in patients with CAD. METHODS AND RESULTS: Xanthine- and NAD(P)H-mediated O*.- formation was determined in coronary arteries from 10 patients with CAD and 10 controls by using electron spin resonance spectroscopy. Furthermore, activity of endothelium-bound xanthine oxidase in vivo and FDD of the radial artery were determined in 21 patients with CAD and 10 controls. FDD was measured before and after infusion of the antioxidant vitamin C (25 mg/min i.a.) to determine the portion of FDD inhibited by radicals. In coronary arteries from patients with CAD, xanthine- and NAD(P)H-mediated O2*- formation was increased compared with controls (xanthine: 12+/-2 versus 7+/-1 nmol O2*-/ microg protein; NADH: 11+/-1 versus 7+/-1 nmol O2*-/ microg protein; and NADPH: 12+/-2 versus 9+/-1 nmol O2*-/ microg protein; each P<0.05). Endothelium-bound xanthine oxidase activity was increased by >200% in patients with CAD (25+/-4 versus 9+/-1 nmol O2*-/ microL plasma per min; P<0.05) and correlated inversely with FDD (r=-0.55; P<0.05) and positively with the effect of vitamin C on FDD (r=0.54; P<0.05). CONCLUSIONS: The present study represents the first electron spin resonance measurements of xanthine and NAD(P)H oxidase activity in human coronary arteries and supports the concept that increased activities of both enzymes contribute to increased vascular oxidant stress in patients with CAD. Furthermore, the present study suggests that increased xanthine oxidase activity contributes to endothelial dysfunction in patients with CAD and may thereby promote the atherosclerotic process.
Asunto(s)
Enfermedad de la Arteria Coronaria/enzimología , Enfermedad de la Arteria Coronaria/fisiopatología , Endotelio Vascular/fisiopatología , NADPH Oxidasas/metabolismo , Xantina Oxidasa/metabolismo , Adulto , Vasos Coronarios/enzimología , Espectroscopía de Resonancia por Spin del Electrón , Endotelio Vascular/enzimología , Humanos , Hipercolesterolemia/enzimología , Hipercolesterolemia/fisiopatología , Masculino , Persona de Mediana Edad , Estrés Oxidativo , Superóxidos/metabolismo , VasodilataciónRESUMEN
BACKGROUND: Impaired flow-dependent, endothelium-mediated vasodilation (FDD) in patients with chronic heart failure (CHF) results, at least in part, from accelerated degradation of nitric oxide by oxygen radicals. The mechanisms leading to increased vascular radical formation, however, remain unclear. Therefore, we determined endothelium-bound activities of extracellular superoxide dismutase (ecSOD), a major vascular antioxidant enzyme, and xanthine-oxidase, a potent radical producing enzyme, and their relation to FDD in patients with CHF. METHODS AND RESULTS: ecSOD and xanthine-oxidase activities, released from endothelium into plasma by heparin bolus injection, were determined in 14 patients with CHF and 10 control subjects. FDD of the radial artery was measured using high-resolution ultrasound and was assessed before and after administration of the antioxidant vitamin C (25 mg/min; IA). In patients with CHF, endothelium-bound ecSOD activity was substantially reduced (5.0+/-0.7 versus 14.4+/-2.6 U x mL(-1) x min(-1); P<0.01) and closely related to FDD (r=0.61). Endothelium-bound xanthine-oxidase activity was increased by >200% (38+/-10 versus 12+/-4 nmol O2*- x microL(-1); P<0.05) and inversely related to FDD (r=-0.35) in patients with CHF. In patients with low ecSOD and high xanthine-oxidase activity, a greater benefit of vitamin C on FDD was observed, ie, the portion of FDD inhibited by radicals correlated negatively with ecSOD (r=-0.71) but positively with xanthine-oxidase (r=0.75). CONCLUSIONS: These results demonstrate that both increased xanthine-oxidase and reduced ecSOD activity are closely associated with increased vascular oxidative stress in patients with CHF. This loss of vascular oxidative balance likely represents a novel mechanism contributing to endothelial dysfunction in CHF.