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Titolo:
Chronic activation of central alpha(2)-adrenoceptors prevents hypertensionin DOCA-salt rats
Autore:
Cabral, AM; da Silva, IF; Gardioli, CR; Menegaz, RG;
Indirizzi:
Fed Univ Espirito Santo, Biomed Ctr, Dept Physiol Sci, BR-29040090 Vitoria, ES, Brazil Fed Univ Espirito Santo Vitoria ES Brazil BR-29040090 BCtoria, ES, Brazil
Titolo Testata:
AUTONOMIC NEUROSCIENCE-BASIC & CLINICAL
fascicolo: 3, volume: 82, anno: 2000,
pagine: 146 - 153
SICI:
1566-0702(20000814)82:3<146:CAOCAP>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
BLOOD-PRESSURE; RENAL-FUNCTION; CLONIDINE; AGONISTS; WATER; SITE;
Keywords:
DOCA-salt hypertension; xylazine; yohimbine; alpha(2)-adrenoceptor; urinary sodium excretion; renal excretory function; renal nerve activity;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
24
Recensione:
Indirizzi per estratti:
Indirizzo: Cabral, AM Fed Univ Espirito Santo, Biomed Ctr, Dept Physiol Sci, BR-29040090 Vitoria, ES, Brazil Fed Univ Espirito Santo Vitoria ES Brazil BR-29040090 BCBrazil
Citazione:
A.M. Cabral et al., "Chronic activation of central alpha(2)-adrenoceptors prevents hypertensionin DOCA-salt rats", AUTON NEURO, 82(3), 2000, pp. 146-153

Abstract

The effects of chronic intracerebroventricular (i.c.v.) injections of the alpha(2)-adrenoceptor agonist, xylazine, on blood pressure were examined inDOCA-salt rats. Acute studies also examined the renal sympathetic nerve activity (RSNA) and renal excretory responses produced by i.c.v. xylazine in rats with established DOCA-salt hypertension. Rats implanted with a chronici.c.v. cannula for drug injection were used. In chronic studies, four groups were investigated: control rats treated with s.c. soybean oil and i.c.v.saline; DOCA-salt rats (s.c. deoxycorticosterone acetate) receiving i.c.v.saline, xylazine or the alpha(2)-adrenoceptor antagonist, yohimbine. During vehicle or DOCA-salt treatment, xylazine (0.2 ng/mu g) or yohimbine (10 mu g/kg) was injected i.c.v. daily (three times). In DOCA-salt rats receiving i.c.v. saline, resting mean arterial pressure (MAP) was elevated on days 15 and 30 (135+/-5 and 160+/-6 mmHg, respectively). Chronic i.c.v. xylazinesignificantly attenuated the rise in MAP produced by DOCA-salt (day 15, 118+/-5 mmHg; day 30, 121+/-4 mmHg). Alternatively, chronic i.c.v. yohimbine shortened the onset (day 15, 152+/-7 mmHg) and augmented the hypertension in DOCA-salt rats (0 survival by day 30). In acute studies, i.c.v. xylazine elicited a profound natriuresis and diuresis as well as a reduction in RSNAwithout altering MAP. This study demonstrates that the ongoing (tonic) activity of central alpha(2)-adrenoceptor mechanisms are critically involved in regulating blood pressure in the DOCA-salt treated rat. In this manner, an enhanced activity of central alpha(2)-adrenoceptor systems acts to protect against a rise in blood pressure. In contrast, the attenuation of centralalpha(2)-adrenoceptor stimulation evokes hypertension. The central action of xylazine to prevent hypertension may be associated with the inhibition of sympathetic outflow to the kidneys and evokes an enhanced natriuresis. Byinhibiting the avid sodium retention elicited by DOCA-salt treatment, the central activation of alpha(2)-adrenoceptors delays the onset and the severity of hypertension in this pathological model. (C) 2000 Published by Elsevier Science B.V. All rights reserved.

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Documento generato il 25/01/20 alle ore 10:19:40