Impaired function of alpha-2 adrenoceptors in smooth muscle of mesenteric arteries from spontaneously hypertensive rats

Impaired function of alpha-2 adrenoceptors in smooth muscle of mesenteric arteries from spontaneously hypertensive rats

Author Feres, Teresa Autor UNIFESP Google Scholar
Borges, Antonio Carlos Romao Autor UNIFESP Google Scholar
Silva, Eneida de Gusmão Autor UNIFESP Google Scholar
Paiva, Antonio Cechelli de Mattos Autor UNIFESP Google Scholar
Paiva, Therezinha Bandiera Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Abstract 1 the alpha(2)-adrenoceptor function in mesenteric arteries of spontaneously hypertensive rats (SHR) was investigated by comparing membrane potential changes in response to adrenergic agonists in preparations from female SHR, Wistar-Kyoto (WKY) and normotensive Wistar rats (NWR).2 Resting membrane potential was found to be less negative in mesenteric arteries from SHR than in those from NWR and WKY. Apamin induced a decrease in the membrane potential of mesenteric artery rings without endothelium from NWR and WKY, but had no effects in those from SHR. Both UK 14,304 and adrenaline, in the presence of prazosin, induced a hyperpolarization that was significantly lower in de-endothelialized mesenteric rings from SHR than in those from NWR and WKY. in mesenteric rings with endothelium, however, similar hyperpolarization was observed in the three strains.3 in NWR mesenteric rings with endothelium the hyperpolarization induced by activation of alpha(2)-adrenoceptors was abolished by apamin, whereas in intact SHR mesenteric rings this hyperpolarization was slightly reduced by apamin and more efficiently reduced by N-omega-nitro-L-arginine.4 It is concluded that the activity of potassium channels coupled to alpha(2)-adrenoceptors is altered in the smooth muscle cells of SHR mesenteric arteries, contributing to their less negative membrane potential. On the other hand, the endothelial alpha(2)-receptors are functioning in mesenteric vessels from SHR and their stimulation induces a hyperpolarization mainly through the release of nitric oxide.
Keywords alpha-2 adrenoceptors
mesenteric arteries
endothelium
spontaneously hypertensive rats
potassium channels
membrane potential
Language English
Date 1998-11-01
Published in British Journal of Pharmacology. Basingstoke: Stockton Press, v. 125, n. 6, p. 1144-1149, 1998.
ISSN 0007-1188 (Sherpa/Romeo, impact factor)
Publisher Stockton Press
Extent 1144-1149
Origin http://dx.doi.org/10.1038/sj.bjp.0702177
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000077085800005
URI http://repositorio.unifesp.br/handle/11600/25970

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