Water intake in hypovolemic sheep: effects of crushing the left atrial appendage.

Sheep increased their water intake in proportion to the amount of protein-free, isosmotic fluid that was removed from their blood by ultrafiltration. This behavioral response to hypovolemia was eliminated by crushing the left atrial appendage of the heart. The surgical maneuver had no effect on basal water intake or on the drinking response to a salt load. These findings suggest that left atrial stretch receptors, which influence secretion of antidiuretic hormone when stimulated, may also play an important role in mediating thirst during hypovolemia.