Role of endogenous angiotensin II on glutamatergic actions in the rostral ventrolateral medulla in Goldblatt hypertensive rats

• Autor(a) principal: Carvalho, Tais Helena F [UNIFESP]
• Data de Publicação: 2003
• Outros Autores: Bergamaschi, Cassia Toledo [UNIFESP], Lopes, Oswaldo Ubriaco [UNIFESP], Campos, Ruy Ribeiro [UNIFESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNIFESP
• Texto Completo: http://dx.doi.org/10.1161/01.HYP.0000086524.35251.2D; http://repositorio.unifesp.br/handle/11600/27423
• topic: brain; angiotensin; captopril; amino acid; sympathetic nervous system

In this study, we investigated the cardiovascular responses mediated by rostral ventrolateral medulla neurons (RVLM) in the Goldblatt hypertension model (2K-1C) treated or not treated with captopril. the actions of glutamate into the RVLM were tested, injecting glutamate (0.1 mol/L, 100 nL) and its antagonist kynurenic acid (0.02 mol/L, 100 nL). Glycine (0.5 mol/L, 100 nL) was also microinjected. Experiments were performed in male Wistar rats (weight, 250 to 300 g); 5 groups were studied: (1) 2K-1C nontreated (H, n=6); (2) 2K-1C treated with captopril, 10 mg/kg per day (Ht10, n = 10); (3) 2K-1C treated with captopril, 50 mg/kg per day (Ht50, n=7); (4) control normotensive rats (N, n=7); and (5) normotensive rats treated with captopril, 50 mg/kg per day (Nt50, n = 8). All experiments in 2K-1C were performed 6 weeks after renal surgery; captopril treatment lasted for the last 2 weeks. in urethane-anesthetized rats (1.2 g/kg IV), bilateral microinjection of glycine into the RVLM caused a depressor response; there was no difference between groups in relation to the change of variation (N: 54+/-2; H: 46+/-12; Ht10: 50+/-3, and Ht50: 42+/-7 mm Hg). Only in the H group, kynurenic acid microinjection into the RVLM caused a depressor response (H: 158+/-8 to 132+/-8 mm Hg). Glutamate response was larger in hypertensive than in normotensive rats (N: 38+/-2.6 and H: 55+/-6); no difference was observed between hypertensive groups. the data suggest that glutamate acts tonically to drive the RVLM in 2K-1C rats, and this action is modulated by endogenous angiotensin II. the increase in the glutamate actions within the RVLM may contribute to the pathogenesis of renovascular hypertension.