Antihypertensive responses elicited by central moxonidine in rats: Possible role of nitric oxide

Antihypertensive responses elicited by central moxonidine in rats: Possible role of nitric oxide

Autor Moreira, Thiago Santos Autor UNIFESP Google Scholar
Takakura, Ana Carolina Thomaz Autor UNIFESP Google Scholar
Sato, Monica Akemi Google Scholar
Menani, Jose Vanderlei Google Scholar
Colombari, Eduardo Autor UNIFESP Google Scholar
Instituição Universidade Federal de São Paulo (UNIFESP)
Universidade Federal do ABC (UFABC)
UNESP
Resumo In the present study, we investigated the effects of pretreatment with N-G-nitro-L-arginine methyl ester (L-NAME) (nitric oxide synthase inhibitor) injected intravenously (IV) on the hypotension, bradycardia, and vasodilation produced by moxonidine (alpha(2)-adrenergic/imidazoline receptor agonist) injected into the fourth brain ventricle (4th V) in rats submitted to acute hypertension that results from baroreflex blockade by bilateral injections of kynurenic acid (kyn, glutamatergic receptor antagonist) into the nucleus of the solitary tract (NTS) or in normotensive rats. Male Wistar rats (n = 5 to 7/group) anesthetized with IV urethane (1.0 g kg(-1) of body weight) and a-chloralose (60mg kg(-1) of body weight) were used. Bilateral injections of kyn (2.7 nmol 100 nL(-1)) into the NTS increased baseline mean arterial pressure (148 +/- 11 mm Hg, vs. control: 102 +/- 4mm Hg) and baseline heart rate (417 +/- 11 bpm, vs. control: 379 +/- 6 bpm). Moxonidine (20 nmol mu L-1) into the 4th V reduced mean arterial pressure and heart rate to similar levels in rats treated with kyn into the NTS (68 +/- 9 mm Hg and 359 +/- 7 bpm) or in control normotensive rats (66 +/- 7 mm Hg and 362 +/- 8 bpm, respectively). the pretreatment with L-NAME (2 5 mu mol kg-1, IV) attenuated the hypotension produced by moxonidine into the 4th V in rats treated with kyn (104 +/- 6 mm Hg) or in normotensive rats (95 +/- 8 mm Hg), without changing bradycardia. Moxonidine into the 4th V also reduced renal, mesenteric, and hindquarter vascular resistances in rats treated or not with kyn into the NTS and the pretreatment with L-NAME IV reduced these effects of moxonidine. Therefore, these data indicate that nitric oxide mechanisms are involved in hypotension and mesenteric, renal, and hindquarter vasodilation induced by central moxonidine in normotensive and in acute hypertensive rats.
Palavra-chave sympathetic
alpha(2)-adrenergic/imidazoline receptor
blood pressure
hypertension
L-NAME
Idioma Inglês
Data de publicação 2006-06-01
Publicado em Journal of Cardiovascular Pharmacology. Philadelphia: Lippincott Williams & Wilkins, v. 47, n. 6, p. 780-787, 2006.
ISSN 0160-2446 (Sherpa/Romeo, fator de impacto)
Publicador Lippincott Williams & Wilkins
Extensão 780-787
Fonte http://dx.doi.org/10.1097/01.fjc.0000211794.68152.04
Direito de acesso Acesso aberto Open Access
Tipo Artigo
Web of Science WOS:000239036600009
Endereço permanente http://repositorio.unifesp.br/handle/11600/28920

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