Role of angiotensin ii and catecholamines to blood pressure
variability responses to stress in spontaneously hypertensive
rats.
Gaudet, Elisabeth, Jocelyne Blanc, Jean-Luc Elghozi.
Laboratory of Pharmacology, CNRS URA 1482, Faculty of Medicine
Necker-Enfants Malades, 156 rue de Vaugirard, 75015 Paris, France,
Phone: 33/1/45 66 55 85, Fax: 33/1/40 61 55 84
APStracts 2:0343R, 1995.
The contribution of the renin-angiotensin system (RAS) and the
sympathetic nervous system (SNS) to blood pressure (BP) and heart
rate (HR) variability responses to air-jet stress was assessed in SHR
and in WKY rats. Activity of the endogenous RAS was suppressed by
chronic treatment by a nonpeptide angiotensin II receptor antagonist
(losartan). The role of [alpha]1 adrenoceptor activity was evaluated
in rats by acute administration of prazosin. In untreated animals,
air-jet induced an increase in systolic BP (SBP) (9 +/- 2 mmHg for
WKY and 8 +/- 2 mmHg for SHR) and in HR (56 +/- 19 bpm for WKY and 76
+/- 8 bpm for SHR) followed by an increase of the mid frequency (0.2
-0.6 Hz, MF) component of HR in WKY (183 %) and by an increase of the
MF component of SBP and diastolic BP (DBP) in SHR (65%). Prazosin
prevented BP rises as well as MF component of BP and HR increases
associated with air-jet stress. Chronic suppression of the RAS by
losartan did not alter the BP response to air-jet in WKY and slightly
reduced it in SHR but abolished all the BP and HR variability changes
in both strains. These results indicate that the SNS but not RAS is
essential for the BP rise induced by stress and demonstrate that RAS
in conjunction with SNS is involved in BP and HR variability changes
associated with stress.
Received 18 January 1995; accepted in final form 5 December 1995.
APS Manuscript Number R37-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 December 95