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Titolo:
ROLE OF ENDOGENOUS ANG-II AND AT(1) RECEPTORS IN REGULATING ARTERIAL BAROREFLEX RESPONSES IN NEWBORN LAMBS
Autore:
SEGAR JL; MINNICK A; NUYT AM; ROBILLARD JE;
Indirizzi:
UNIV IOWA HOSP & CLIN,DEPT PEDIAT,200 HAWKINS DR IOWA CITY IA 52242 UNIV IOWA,DEPT PEDIAT IOWA CITY IA 52242 UNIV IOWA,CTR CARDIOVASC IOWA CITY IA 52242
Titolo Testata:
American journal of physiology. Regulatory, integrative and comparative physiology
fascicolo: 6, volume: 41, anno: 1997,
pagine: 1862 - 1873
SICI:
0363-6119(1997)41:6<1862:ROEAAA>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
SPONTANEOUSLY HYPERTENSIVE RATS; SYMPATHETIC-NERVE ACTIVITY; NUCLEUS-TRACTUS-SOLITARII; ANGIOTENSIN-II; HEART-RATE; VENTROLATERAL MEDULLA; BARORECEPTOR REFLEX; ANTAGONIST LOSARTAN; CONSCIOUS RABBITS; CHRONIC INFUSION;
Keywords:
BLOOD PRESSURE; HEART RATE; RENAL SYMPATHETIC NERVE ACTIVITY; PHENYLEPHRINE; NITROPRUSSIDE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
52
Recensione:
Indirizzi per estratti:
Citazione:
J.L. Segar et al., "ROLE OF ENDOGENOUS ANG-II AND AT(1) RECEPTORS IN REGULATING ARTERIAL BAROREFLEX RESPONSES IN NEWBORN LAMBS", American journal of physiology. Regulatory, integrative and comparative physiology, 41(6), 1997, pp. 1862-1873

Abstract

The present study was designed to test the hypothesis that endogenousangiotensin II (ANG II) influences baroreflex control of heart rate (HR) and renal sympathetic nerve activity (RSNA) early in life and to determine whether these actions are mediated by angiotensin AT(1) or AT(2) receptors. To test this hypothesis, we studied the effects of systemic and central administration of losartan, a selective AT(1) receptor antagonist, and PD-123319, a selective AT(2) antagonist, on baroreflex-mediated control of HR and RSNA in conscious newborn lambs. Systemic administration of losartan decreased resting mean arterial blood pressure (MABP) from 70 +/- 3 to 58 +/- 4 mmHg (P < 0.05) without producing reflex increases in HR or RSNA. The baroreflex response curves wereshifted to the left as indicated by a decrease in the arterial pressure at the midpoint of the curve for HR (83 +/- 3 to 75 +/- 4 mmHg) andRSNA (74 +/- 2 to 69 +/- 3 mmHg; P < 0.05 for both). Losartan also reset HR and RSNA baroreflex curves when changes in baseline blood pressure were prevented by simultaneous infusion of phenylephrine. In contrast, a sustained decrease in arterial pressure of 10-12 mmHg with nitroprusside failed to shift the baroreflex function curves. PD-123319 had no effect on baseline HR, MABP, RSNA, or baroreflex responses. Lateral ventricle administration of losartan but not PD123319 also produceda decrease in arterial pressure (81 +/- 4 to 73 +/- 3 mmHg, P < 0.05)and reset the baroreflex for HR and RSNA toward lower pressure. Theseresults demonstrate that. early in life, endogenous ANG II exerts a tonic effect on baroreflex control of HR and RSNA to shift. the curves toward higher pressure levels. The alterations in arterial baroreflex function appear independent of direct ANG II effects on arterial pressure and are mediated by AT(1) receptors.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 15/08/20 alle ore 19:20:00