ADDITIVITY OF STIMULI FOR DRINKING IN RATS

In Exp. I 18 water-deprived rats were injected intravenously with hypertonic NaCl and, in Exp. II, 16 Ss were bled. Factorial analyses of variance and regression tests indicated in both cases that effects of the 2 procedures were strictly additive and caused more drinking than any single procedure, suggesting that, during deprivation of water, the sum of cellular and extracellular deficits may determine the amount to be drunk. This result partly explains why water deprivation is a more effective stimulus of thirst than osmotically equivalent injections of NaCl. Another factor is that serum Na concentration increased by only 2.9% in 48 hr. of water deprivation. (19 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1968 American Psychological Association.