AJP - Endocrinology and Metabolism, Vol 254, Issue 4 E490-E495, Copyright © 1988 by American Physiological Society
Effect of vasopressin blockade on blood pressure during water deprivation in intact and baroreceptor-denervated conscious dogs
L. C. Gregory, E. W. Quillen Jr, L. C. Keil, D. Chang and I. A. Reid
Department of Physiology, University of California, San Francisco 94143.
Previous studies have provided evidence that vasopressin plays an important
role in blood pressure regulation during water deprivation. However, these
investigations have been complicated by reflex compensatory increases in
cardiac output and renin secretion. The aim of the present study was to
investigate the effect of blockade of the vasoconstrictor action of
vasopressin in conscious water-deprived dogs in which the low- and/or
high-pressure baroreceptors were denervated to minimize reflex responses.
Vasopressin blockade in sham-operated dogs (n = 7) did not change arterial
pressure. Heart rate rose from 78 +/- 9 to 119 +/- 13 beats/min (P less
than 0.01), and plasma renin activity increased from 10.9 +/- 2.1 to 21.6
+/- 4.6 ng.ml-1.3 h-1 (P less than 0.01). In carotid sinus-denervated dogs
(n = 6), vasopressin blockade again failed to decrease arterial pressure.
Heart rate increased from 105 +/- 10 to 132 +/- 10 beats/min (P less than
0.01), and plasma renin activity rose from 6.8 +/- 1.7 to 15.5 +/- 2.4
ng.ml-1.3 h-1 (P less than 0.01). The antagonist also failed to change
blood pressure in cardiac-denervated dogs (n = 5). Heart rate increased
from 111 +/- 9 to 119 +/- 1 beats/min (P less than 0.01), but plasma renin
activity did not increase significantly. In marked contrast, vasopressin
blockade in sinoaortic/cardiac-denervated dogs (n = 7) promptly decreased
arterial pressure from 115 +/- 8 to 94 +/- 7 mmHg (P less than
0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
