Gastric distention and thirst: Relevance to the osmotic thirst threshold and metering of water intake

Abstract

The osmotic reactivity of the thirst mechanism was measured in dogs when gastric distention was started immediately before intravenous infusion of 5% NaCl, simultaneously with the infusion, and 10–20 or 30–40 min prior to it. Volume of water drunk after 30, 60 and 120 min of the infusion was measured. The effects of distention of the stomach was also determined during drinking and the size of single draughts as well as the cumulative amount of water drunk during 25 min of 5% NaCl infusion were measured. Gastric distention did not influence the osmotic thirst threshold. It was similar independently of the time at which the 5% NaCl infusion was initiated. Total water intake did not change after hypertonic saline infusion; however, gastric distention prolonged the time in which the dogs usually completed drinking (30 min) up to 2 hr. Distention of the stomach during drinking neither interrupted water intake nor changed the pattern of drinking during the hypertonic saline infusion. These results question the role of gastric stretch receptors in the drinking response.