AJP - Regulatory, Integrative and Comparative Physiology, Vol 241, Issue 3 152-R157, Copyright © 1981 by American Physiological Society
Isoproterenol-induced thirst: renal and extrarenal mechanisms
R. Rettig, D. Ganten and A. K. Johnson
When given systemically, isoproterenol will induce water intake in various
species. The drug also causes hypotension and renin release from the
kidney. Angiotensin II and arterial baroreceptors have been hypothesized to
be involved in the mediation of beta-adrenoceptor agonist-induced thirst,
but their relative importance has been disputed. In the present series of
experiments, isoproterenol was infused intravenously at different rates
into nephrectomized and ureteric-ligated rats. Thus, different levels of
hypotension could be achieved and maintained while water intake was
measured. Also, plasma levels of angiotensin II were determined in
ureteric-ligated rats following the intravenous infusion of a dipsogenic
dose of isoproterenol. The results indicate that for moderate blood
pressure changes a renal-related factor, probably angiotensin II, plays a
major role in the mediation of isoproterenol-induced thirst. Under extreme
conditions involving a very dramatic drop of arterial blood pressure,
extrarenal mechanisms (e.g., arterial baroreceptors) are implicated.
