Drinking Behavior in Water Deprived Rats after Angiotensin Receptor Blockade

Angiotensin II is a peptide normally present in the bloodstream and central nervous system. Exogenous angiotensin induces drinking which is inhibited by saralasin, a specific receptor antagonist. Administration of saralasin does not reduce endogenously stimulated drinking. Angiotensin is dipsogenic after intravenous or intracerebroventricular infusion, raising the possibility of multiple access routes to the brain. Water deprived rats were given saralasin by both routes simultaneously to block the access of endogenous angiotensin to recentors reached from blood and ventricular cerebrospinal fluid (CSF). Water deprivation increased plasma (Na+), hematocrit, vasopressin content and renin activity but saralasin treatment did not reduce water intake after 30 or 60 min. Therefore, blood or CSF-bore angiotensin does not appear to be an absolute requirement for water deprivation drinking behavior.