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(Hypertension. 2005;46:1362.)
© 2005 American Heart Association, Inc.
Original Articles |
From the Department of Cardiovascular Diseases, Medical School, P. Universidad Católica de Chile (J.E.J., M.P.O., A.P., J.B., A.G.), and Departamento de Bioquímica and Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas (J.B., A.G., I.G., S.L.), ICBM, Facultad de Medicina (S.L.) and Centro FONDAP Estudios Moleculares de la Célula (S.L.), Universidad de Chile, Santiago.
Correspondence to Dr Jorge Jalil, Departamento de Enfermedades Cardiovasculares, Escuela de Medicina, P. Universidad Católica de Chile, Lira 85, Piso 2, Santiago, Chile. E-mail jjalil{at}med.puc.cl or Dr Sergio Lavandero, Departamento Bioquímica and Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Olivos 1007, Santiago 664-0750, Chile. E-mail slavander@uchile.cl
In humans and rats, angiotensin Iconverting enzyme activity is significantly determined by a gene polymorphism. Homozygous Brown Norway rats have higher plasma angiotensin Iconverting enzyme activity and circulating angiotensin II (Ang II) levels than Lewis rats. Because Ang II induces NAD(P)H oxidase activation, we hypothesized here that Brown Norway rats have higher vascular NAD(P)H oxidase activity and superoxide anion production than Lewis rats. Homozygous Brown Norway (n=15) and Lewis (n=13) male rats were used. Plasma angiotensin Iconverting enzyme activity (by fluorimetry), Ang II levels (by high-performance liquid chromatography and radioimmunoassay), and aortic NAD(P)H oxidase activity, as well as superoxide anion production (by chemiluminescence with lucigenin) were measured. Plasma angiotensin Iconverting enzyme activity and Ang II levels were 100% higher in Brown Norway rats than in Lewis rats (P<0.05). Aortic angiotensin I converting enzyme, but not Ang II, was elevated (P<0.05). Aortic superoxide anion production and NAD(P)H oxidase activity were 300% and 260% higher in Brown Norway than in Lewis rats, respectively (P<0.05), which was not observed in Brown Norway rats treated with candesartan (10 mg/kg per day for 7 days). Endothelial NO synthase activity in the aorta from Brown Norway rats was significantly lower than in Lewis rats. However, inducible NO synthase activity and both endothelial NO synthase and inducible NO synthase mRNA and protein levels were similar in both genotypes. In summary, Brown Norway rats have higher vascular NAD(P)H oxidase activity and superoxide anion production than Lewis rats, suggesting the presence of a higher level of vascular oxidative stress in rats with genetically higher angiotensin Iconverting enzyme levels. This effect is mediated through the angiotensin I receptor.
Key Words: angiotensin-converting enzyme polymorphism nitric oxide
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