Chronic stress induces sensitization in sympathoadrenal responses
to stress in borderline hypertensive rats.
Mansi, James A., and Guy Drolet.
Centre de Hospitalier de l'Universit[acute]e Laval, Unit[acute]e de
Recherche sur l'Hypertension and D[acute]epartement de Pharmacologie,
Universit[acute]e Laval
APStracts 3:0323R, 1996.
The effects of acute footshock on cardiovascular and sympathoadrenal
responses were investigated in chronically stressed borderline
hypertensive rats (BHR) and Wistar Kyoto (WKY) rats. Male BHRs were
divided into two groups; the maturation group (MAT) were not stressed
while the chronic stress group (AJS) received 8 weeks (5 days/week,
30 minutes/day) of airjet stress coupled to immobilization. Following
chronic stress, the rats were cannulated in the femoral artery and
jugular vein. Resting mean arterial pressure (MAP), heart rate (HR)
and, plasma norepinepherine (NE) levels were higher in the AJS group.
In contrast, chronic stress failed to increase basal arterial
pressure or heart rate in WKY rats. In response to acute footshock,
the MAT group had higher MAP increases at which they plateaued, while
the AJS rats displayed a progressive decline in MAP. This was
associated with higher plasma NE and epinepherine (EPI) levels but a
smaller increase in adrenocorticotropic hormone (ACTH) in AJS versus
MAT rats. This hyperactivity in the sympathoadrenal system of
chronically stressed BHRs may, in part, account for their mild
hypertension.
Received 11 April 1996; accepted in final form 20 August 1996.
APS Manuscript Number R207-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 19 September 1996