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Titolo:
Brain renin-angiotensin system and ouabain-induced sympathetic hyperactivity and hypertension in Wistar rats
Autore:
Huang, BS; Leenen, FHH;
Indirizzi:
Univ Ottawa, Inst Heart, Hypertens Unit, Ottawa, ON K1Y 4W7, Canada Univ Ottawa Ottawa ON Canada K1Y 4W7 ens Unit, Ottawa, ON K1Y 4W7, Canada
Titolo Testata:
HYPERTENSION
fascicolo: 1, volume: 34, anno: 1999,
pagine: 107 - 112
SICI:
0194-911X(199907)34:1<107:BRSAOS>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
PERIPHERAL OUABAIN; SODIUM; DIGOXIN; FACILITATION; HYPOTHALAMUS; INHIBITOR; RECEPTORS; RELEASE; MACAQUE; DOGS;
Keywords:
baroreflex; renal nerves; stress, air-jet; guanabenz; renin-angiotensin system;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Life Sciences
Citazioni:
32
Recensione:
Indirizzi per estratti:
Indirizzo: Leenen, FHH Univ Ottawa, Inst Heart, Hypertens Unit, 40 Ruskin St, Ottawa,ON K1Y 4W7,Canada Univ Ottawa 40 Ruskin St Ottawa ON Canada K1Y 4W7 Y 4W7,Canada
Citazione:
B.S. Huang e F.H.H. Leenen, "Brain renin-angiotensin system and ouabain-induced sympathetic hyperactivity and hypertension in Wistar rats", HYPERTENSIO, 34(1), 1999, pp. 107-112

Abstract

In Dahl salt-sensitive rats on a high salt diet or normotensive rats with chronic central infusion of sodium, increased brain "ouabain" results in sympathetic hyperactivity and hypertension, possibly by activating the brain renin-angiotensin system. In the present study, we tested whether the hypertension caused by exogenous ouabain also depends on activation of brain renin-angiotensin system. In Wistar rats, ouabain (50 mu g/d) was infused subcutaneously for 14 days with the use of osmotic minipumps. Concomitantly, inone group, the angiotensin II type 1 receptor blocker losartan (1 mg/kg per day) was infused intracerebroventricularly. On day 15, mean arterial pressure, heart rate, central venous pressure, and renal sympathetic nerve activity were recorded in conscious rats at rest and in response to air-jet stress, intracerebroventricular injection of the alpha(2)-agonist guanabenz (25 and 75 mu g) or angiotensin II (30 ng), acute volume expansion, and ramp changes of blood pressure by +/-50 mmHg with phenylephrine and nitroprusside. Compared with control rats, in rats treated with ouabain, resting mean arterial pressure was significantly increased (111+/-4 versus 93+/-3 mm Hg; P<0.05), and increases or decreases in mean arterial pressure, heart rate, and renal sympathetic nerve activity in response to air stress or guanabenzwere enhanced significantly. These effects of ouabain were prevented when losartan was given concomitantly. Maximal slopes of arterial baroreflex control of renal sympathetic nerve activity and heart rate tended to be decreased in ouabain-treated versus control rats and were significantly increasedin ouabain-treated rats with versus without losartan. No differences in cardiopulmonary baroreflex function were detected. It seems that by day 14 to15, the central effect of ouabain on baroreflex control prevails over its peripheral sensitizing effect on baroreceptors, leading to a tendency of desensitization. These results indicate that chronic administration of ouabain activates the brain renin-angiotensin system, resulting in decreased sympathoinhibition and increased sympathoexcitation, impairment of baroreflex function, and hypertension.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/09/20 alle ore 03:58:05