The specificity of the dipsogenic effect of angiotensin II.

The specificity of choice in drinking by sheep was examined when a cafeteria of water and of 900 mmol/1 solutions of NaCl and KCl was presented, during intracarotid infusion of angiotensin II (800-1200 ng/min) or 4M NaCl (1.6 ml/min), and following 48 hr of water deprivation or following Na depletion. Water was the fluid of predominant choice with angiotensin II, 4M NaCl infusion and water deprivation. The hypertonic NaCl was the clear choice of the Na deficient animals. With a cafeteria of 300 mmol/l solutions, there was no clear discrimination between NaCl and water with intracarotid angiotensin II infusion. A 2 choice study of taste preference for water or NaCl concentrations with free access indicated sheep elect to take more of higher NaCl concentrations than the rat, and that 300 mmol/1 NaCl is not less preferred than water in sheep. The data indicated, overall, that the dipsogenic effect of supraphysiological cerebral blood concentrations of angiotensin II is biased to water drinking when the choice is between water and 900 mM NaCl and KCl solutions. It does not induce any specific salt appetite.