Gastric factors controlling water- and salt-solution-drinking.

Abstract

The role of gastric factors in the control of water drinking and the drinking of salt solns. was studied experimentally by a stomach-tubing technique that permits direct introduction of solns. into the rat stomach, without involvement of taste and other mouth receptors. Drinking increases as a function of concn. of soln. drunk up to the isotonic point, and then it decreases (preference-aversion function). Hypertonic loads elevate the drinking of water and hypotonic solns. and depress the drinking of hypertonic solns. Comparable water loads depress the drinking of water and hypo-tonic solns. and elevate the drinking of hypertonic solns. Vols. of load as small as 0.5 cc. affect drinking as descr. above; but vols. as large as 10.0 cc. tend to depress drinking under all conditions except where 3% NaCl is loaded and water is drunk. In this one condition, drinking is elevated dramatically. Making animals wait for 1 hr. between loading and drinking yields substantially the same result as allowing them to drink immediately after loading. Animals with esophageal fistulas exhibit preference-aversion curves for NaCl; but their ingestion of hypertonic solns. is much higher than that of control animals, emphasizing the inhibitory role of hypertonic solns. in the stomach in the normal animal. Apparently water drinking and the drinking of salt solns. are under the control of: (a) Taste and other sensory mechanisms in the mouth, (b) gastric distension, and (c) dehydration produced by osmotic effects of hypertonic solns. on the stomach.