AJP - Heart and Circulatory Physiology, Vol 244, Issue 1 115-H120, Copyright © 1983 by American Physiological Society
Role of angiotensin and vasopressin on blood pressure of ganglionic blocked dogs
P. C. Houck, M. J. Fiksen-Olsen, S. L. Britton and J. C. Romero
This study was designed to investigate the possible role of angiotensin and
vasopressin in the maintenance of arterial blood pressure during acute
blockade of the autonomic nervous system. Two groups of eight dogs each
were anesthetized with pentobarbital sodium, and autonomic ganglia were
blocked with hexamethonium (20 mg/kg). Thirty minutes later group 1
received the vasopressin antagonist 1-(beta-mercapto-beta,
beta-cyclopentamethylene propionic acid),2-(O-methyl)tyrosine arginine
vasopressin (10 micrograms/kg) followed after a 30-min interval by
captopril (1 mg/kg). Group 2 received the same drugs, except the order of
administration of vasopressin antagonist and captopril was reversed.
Vasopressin antagonist during ganglionic blockade (group 2) produced a
greater fall in blood pressure than did captopril during ganglionic
blockade (group 1). These data indicate that vasopressin plays a greater
pressor role than angiotensin in the acute response to ganglionic blockade.
Additional studies were performed to determine if the autonomic nervous
system alone can support the resting blood pressure in the anesthetized
dog. Combined blockade of angiotensin and vasopressin without autonomic
blockade produced a significant decrease in blood pressure, suggesting that
the autonomic nervous system alone is not able to support the control blood
pressure in the anesthetized dog.
