Defense of water balance in the rat.

Abstract

Effects of size of daily ration of water on weight, food intake, and rate of bar pressing for various concentrations of sucrose were examined. Linear relations of log weight, food intake, and log rate of bar pressing with log intake of water were found. The results suggest that in the presence of a chronic water deficit there is a reduction in body size which defends the ratio of body water to lean body mass; that this reduction in size is brought about by means of voluntary reduction in food intake; and that asymptotic weight loss on a given schedule may provide 1 useful measure of thirst.