title: Hypertension induced by nitric oxide synthase inhibition activates the atrial natriuretic peptide (ANP) system.
abstract: We assessed the effect of nitric oxide (NO) synthase inhibition on plasma atrial natriuretic peptide (ANP) concentration and content in some brain structures [neurohypophysis (NH), adenohypophysis (AH), medial basal hypothalamus (MHB) and olfactory bulb (OB)] in rats before and after blood volume expansion (BVE). Male Wistar rats were injected i.p. with N(pi)-nitro-L-arginine (L-NNA), 25 mg/kg of body weight, 40 min before the experiment (acute treatment) or L-NNA at a dose of 25 mg/kg body weight, twice a day, for 4 days (chronic treatment). The acute treatment caused an increase in the blood pressure and plasma ANP concentration in rats under basal conditions and after BVE. A decrease in ANP content was observed in the OB and NH, whereas no significant changes were found in the AH or MBH. In chronically treated rats, we also found an increase in blood pressure and in plasma ANP concentration under basal conditions and after BVE. The ANP content increased in the OB, NH and AH. These results indicate that systemic NO synthase inhibition increases ANP concentration in plasma and in areas of the central nervous system. We hypothesize that ANP participates in the hypertension-induced by NO synthesis blockade acting by baroreceptors input to the brain to stimulate ANP release and synthesis that reduces NO prival hypertension.
authors.affiliation: Laboratório de Fisiologia, Escola de Enfermagem de Ribeirão Preto, Universidade de São Paulo, 14040-902 Ribeirão Preto, Brazil. carnioec@eerp.usp.br
authors.forename: Evelin C
authors.initials: EC
authors.lastname: Carnio
authors.forename: Valéria
authors.initials: V
authors.lastname: Rettori
authors.forename: Elaine A
authors.initials: EA
authors.lastname: Del Bel
authors.forename: Samuel M
authors.initials: SM
authors.lastname: McCann
authors.forename: Jose
authors.initials: J
authors.lastname: Antunes-Rodrigues
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000097:blood*; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000378:metabolism; D006973:Hypertension / Q000097:blood* / Q000139:chemically induced; D008297:Male; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000502:physiology; D019335:Nitroarginine; D051381:Rats; D017208:Rats, Wistar
chemical_list: D019335:Nitroarginine; D009320:Atrial Natriuretic Factor; D019001:Nitric Oxide Synthase