An angiotensin-independent, hypotension-induced, sodium appetite in the rat

We have investigated the role of peripheral angiotensin II in the generation of hypotension (without hypovolaemia)-induced salt intake in rats treated with an IV infusion of the quaternary ammonium peripheral ganglion blocker Penthonium. At a dose of 15.4 mg/ml this compound induces a significant decrease in blood pressure from the beginning of the infusion. Intake of 3% NaCl was significantly increased only on the first day (1.7 +/- 0.3 ml, n = 7, p < 0.01 vs. the day before) and this induced salt appetite was not altered (2.3 +/- 0.9 ml, n = 7, p < 0.05 vs. the day before) by intracerebroventricular administration of a nonpeptide AII-type 1 receptor specific antagonist, Losartan, at a dose known to block AII-induced drinking (250 ng). We conclude from these results that AII liberated in response to the hypovolaemia is probably not responsible for the subsequent induced intake of NaCl which may be the result of a direct barosensitive input to the salt appetite centers of the brain.