AJP - Regulatory, Integrative and Comparative Physiology, Vol 250, Issue 5 898-R901, Copyright © 1986 by American Physiological Society
Plasma renin and angiotensin in dehydrated and rehydrated rats
R. Di Nicolantonio and F. A. Mendelsohn
The role of the renin-angiotensin system in the stimulation and termination
of dehydration-induced drinking was examined in the rat. Rats dehydrated
for 48 h had significantly elevated renin, angiotensin II, plasma Na+
concentration, osmolality, and hematocrit when compared with replete
controls. Although plasma Na+ concentration, osmolality, and hematocrit of
dehydrated rats had returned to control replete levels by 2-4 h after the
return of water, the plasma renin and angiotensin II levels exhibited a
further increase on rehydration and remained significantly above
dehydration levels for 2-4 h after the return of water. The levels of renin
and angiotensin II in rehydrated rats were maintained at levels in excess
of the dipsogenic threshold for circulating angiotensin II during the 8-h
period after rehydration, indicating that termination of the drinking is
not dependent on a reduction of circulating angiotensin II. Finally,
rehydrated rats did not drink significantly more than replete controls in
the 1- to 8-h postrehydration period despite plasma angiotensin II levels
in excess of that of the dipsogenic threshold for angiotensin II,
indicating that mechanisms exist which override the dipsogenic action of
circulating angiotensin II.
