SPECIFICITY OF DIPSOGENIC EFFECT OF ANGIOTENSINII

Specificity of choice in drinking by sheep was examined when a cafeteria of H2O and of 900 mmol/l solutions of NaCl and KCl was presented, during intracarotid infusion of angiotensin II (800-1200 ng/min) or 4 M NaCl (1.6 ml/min), and following 48 h of H2O deprivation or following Na depletion. H2O was the fluid of predominant choice with angiotensin II, 4 M NaCl infusion and H2O deprivation. Hypertonic NaCl was the choice of Na deficient animals. With a cafeteria of 300 mmol/l solutions, there was no clear discrimination between NaCl and H2O with intracarotid angiotensin II infusion. A 2 choice study of taste preference for H2O or NaCl concentrations with free access indicated sheep elect to take more of higher NaCl concentrations than the rat, and that 300 mmol/l NaCl is not less preferred than H2O in sheep. The dipsogenic effect of supraphysiological cerebral blood concentrations of angiotensin II is biased to H2O drinking when the choice is between H2O and 900 mM NaCl and KCl solutions. It does not induce any specific salt appetite.