AJP - Regulatory, Integrative and Comparative Physiology, Vol 257, Issue 5 1212-R1218, Copyright © 1989 by American Physiological Society

ARTICLES

Sodium appetite and thirst in cattle subjected to dehydration

J. R. Blair-West, D. A. Denton, M. J. McKinley and R. S. Weisinger
Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria, Australia.

Cows having free access to water (hydrated) or deprived of water for 26.5 h (dehydrated) were infused for 3 h with angiotensin II or captopril solutions intravenously (iv) or intracerebroventricularly (icv) beginning 1 h before access to 0.3 M NaHCO3/NaCl solution for 2 h. The results agree with the results of the experiments with the same agents and doses in Na-deficient cows. Only iv infusion of angiotensin II stimulated Na appetite and only icv infusion of angiotensin II stimulated thirst. Therefore, barriers to the penetration of angiotensin II in the brain determined the particular site of action and elicited response. Dehydration did not stimulate Na appetite and, as shown previously, Na deficiency did not stimulate thirst, but both behaviors seem to be influenced by angiotensin-related mechanisms in the brain. The inability of iv angiotensin II to stimulate Na appetite in hydrated cows might be explained by the lack of a response caused by, and common to, Na deficiency and dehydration, e.g., upregulation of angiotensin II receptors, or reduced extracellular fluid volume.

This article has been cited by other articles:

				M. J. Cairns, P. Burns, R. Di Nicolantonio, M. J. McKinley, and M. L. Mathai Influence of brain angiotensin on thermoregulation and hydromineral balance during pregnancy in rats J Appl Physiol, May 1, 2005; 98(5): 1813 - 1819. [Abstract] [Full Text] [PDF]

				J. T. FITZSIMONS Angiotensin, Thirst, and Sodium Appetite Physiol Rev, July 1, 1998; 78(3): 583 - 686. [Abstract] [Full Text] [PDF]