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Type: Artigo de periódico
Title: Acute Administration Of Nicotine Impairs The Hypotensive Responses To Bradykinin In Rats.
Author: Paganelli, M O
Tanus-Santos, J E
Toledo, J C
do Prado, J F
Calegari, V
Moreno, H
Abstract: Nicotine may contribute to smoking-induced endothelial dysfunction because of its ability to impair endothelium-dependent vasodilatation. We investigated whether the acute administration of nicotine changes the hypotensive responses to bradykinin in rats. The effects of pre-treatment with losartan or enalapril on the nicotine-induced changes in the responses to bradykinin were also evaluated. In study 1, anesthetized rats were cannulated via carotid artery for the measurement of mean arterial pressure. Dose-response curves to bradykinin (0.1, 0.4, 1.6, 6.4, 25 and 100 microg/kg) were generated before and 10 min after the injection of nicotine (200 microg/kg, i.v.) or saline. The individual dose-response curves were fitted to a four-parameter logistic equation using the ALLFIT program, which provided an estimate of the maximal response (E(max)) and of the dose of bradykinin producing the half-maximal response (ED(50)). In study 2, rats were pre-treated orally with losartan (10 mg/kg/day) or enalapril maleate (25 mg/kg/day) for 2 weeks. Control rats received tap water alone. After pre-treatment, the rats were anesthetized and used as described in study 1. Nicotine decreased the E(max) (from 73.0+/-7.5 to 65.7+/-3.3 mm Hg; P<0.05) but did not affect the ED(50). In study 2, losartan or enalapril did not affect nicotine-induced decrease in responses to bradykinin; E(max) decreased in both groups (from 68.7+/-6.3 to 62.8+/-4.2 mm Hg, and from 53.8+/-13.0 to 43.1+/-7.1 mm Hg, respectively; P<0.05) without significantly changing the ED(50). These results suggest that nicotine impairs the endothelium-dependent hypotensive responses to bradykinin. This effect is not influenced by inhibition of the angiotensin-converting enzyme or by blockade of the angiotensin AT(1) receptors.
Subject: Angiotensin Receptor Antagonists
Angiotensin-converting Enzyme Inhibitors
Antihypertensive Agents
Blood Pressure
Dose-response Relationship, Drug
Endothelium, Vascular
Ganglionic Stimulants
Rats, Wistar
Receptor, Angiotensin, Type 1
Receptor, Angiotensin, Type 2
Rights: fechado
Identifier DOI: 
Date Issue: 2001
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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