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Titolo:
BAROREFLEX CONTROL OF HEART-RATE AND CARDIAC-HYPERTROPHY IN ANGIOTENSIN-II-INDUCED HYPERTENSION IN RABBITS
Autore:
MALPAS SC; GROOM AS; HEAD GA;
Indirizzi:
UNIV AUCKLAND,SCH MED,DEPT PHYSIOL,PRIVATE BAG 92019 AUCKLAND NEW ZEALAND BAKER MED RES INST PRAHRAN VIC 3181 AUSTRALIA
Titolo Testata:
Hypertension
fascicolo: 6, volume: 29, anno: 1997,
pagine: 1284 - 1290
SICI:
0194-911X(1997)29:6<1284:BCOHAC>2.0.ZU;2-W
Fonte:
ISI
Lingua:
ENG
Soggetto:
RENAL-HYPERTENSION; CHRONIC INFUSION; CONSCIOUS RATS; RATE REFLEX; ARTERIAL; SENSITIVITY;
Keywords:
HEMATOCRIT; HEART RATE; BLOOD PRESSURE HYPERTROPHY, LEFT VENTRICULAR;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
31
Recensione:
Indirizzi per estratti:
Citazione:
S.C. Malpas et al., "BAROREFLEX CONTROL OF HEART-RATE AND CARDIAC-HYPERTROPHY IN ANGIOTENSIN-II-INDUCED HYPERTENSION IN RABBITS", Hypertension, 29(6), 1997, pp. 1284-1290

Abstract

The cardiac hypertrophy observed in hypertension is thought to be responsible for the accompanying deficiency in the baroreflex control of heart rate. In this study, we assessed the baroreflex relationship between heart rate and arterial pressure in a group of seven rabbits during a normotensive period, during the early phase of angiotensin II (Ang II)-induced hypertension (1 week) (50 ng/kg per minute IV via osmotic minipumps), after 7 weeks of continuous hypertension, then 2 days after Ang II was stopped, and finally 7 days after Ang II. Left ventricles were weighed for measurement of left ventricular weight-body weightratio. One week of intravenous Anp II, infusion produced hypertension(mean arterial pressure from 80 +/- 2 up to 115 +/- 8 mm Hg), with significantly increased heart rate and hematocrit. The heart rate-arterial pressure baroreflex curve was shifted to the right, with a significant 45% reduction in the gain of the reflex (-6.4 +/- 1.5 to -3.5 +/- 0.2 beats per minute/mm Hg). After 7 weeks of Ang II, arterial pressure was still elevated (112 +/- 4 mm Hg) and the gain of the baroreflex curve still somewhat attenuated, although it was no longer markedly different from normotensive levels (gain, -5.09 +/- 0.95, 20% reduction from normotensive level). Two days after the Ang II infusion was stopped, arterial pressure had returned to normotensive levels, although hematocrit and heart rate remained elevated. At this time, the baroreflex curve was similar to prehypertensive control levels, with no furtherchanges when measured again 7 days after Ang II. Cardiac hypertrophy was present when measured at 7 days after angiotensin (left ventricular weight-body weight ratio: 1.78 +/- 0.05 versus 1.35 +/- 0.04 g/kg, hypertensive versus normotensive, P<.05). Thus, although Ang II infusion produced an initial deficit in the baroreflex control of heart rate,this effect became less as the hypertension continued. Furthermore, although cardiac hypertrophy developed, its presence did not appear to be sufficient to produce a decrease in barosensitivity independent of raised arterial pressure.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 05/07/20 alle ore 13:31:05