AJP - Heart and Circulatory Physiology, Vol 247, Issue 6 973-H977, Copyright © 1984 by American Physiological Society
Differential effect of vasopressin on angiotensin and norepinephrine pressor action in rats
F. Elijovich, C. R. Barry, L. R. Krakoff and M. Kirchberger
The effect of vasopressin infusion on the pressor dose responses to
angiotensin II and norepinephrine was studied in pentobarbital-anesthetized
and unanesthetized nephrectomized rats. Pressor vasopressin (2-15 ng X kg-1
X min-1) given to anesthetized rats decreased sensitivity to angiotensin II
in a dose-dependent manner (r = 0.88), an effect completely reversible by
dPMeTyrAVP, a vasopressin vascular antagonist. Subpressor vasopressin
(0.5-1 ng X kg-1 X min-1) given to unanesthetized rats diminished
sensitivity to angiotensin II in the presence or absence of pentolinium (10
mg/kg). Shifts in dose-response curves to angiotensin II were always
parallel. In contrast, dose responses to norepinephrine were not modified
by vasopressin in pentolinium-treated rats and showed a small nonparallel
rightward shift in animals without pentolinium. In animals without
pentolinium, the baroreflex-mediated reduction in heart rate elicited by
angiotensin II was not altered by vasopressin infusion. Our data suggest
that vasopressin reduces angiotensin II pressor action by diminishing
pressor sensitivity to the peptide. They indicate that the effect may be
specific, mediated through the vascular receptor for vasopressin and
independent of actions of this hormone on the autonomic nervous system.
