Inhibition of water intake by ouabain administration in sheep

Abstract

Intracarotid infusion of ouabain (1280 ng/min) over 4 1 2 hr virtually abolished water intake of sheep in response to intracarotid infusion of either angiotensin II (800 ng/min) or 4 M NaCl (1.6 ml/min for 20 min). Ouabain treatment did not affect mean arterial pressure either before or during infusion of angiotensin. Neither ouabain nor angiotensin administration affected plasma [Na] or [K] or CSF [K]. During ouabain, but not during control infusion, angiotensin administration significantly decreased CSF [Na]. Ouabain administration also decreased water intake after 23 1 2 or 48 hr water deprivation. In the 23 1 2 hr deprivation experiments, food was made available immediately prior to wate..