The mechanism and significance of pentagastrin-stimulated water intake in the pig.

The role of gastric secretion in drinking was investigated. Treatment of pigs with cimetidine (300 mg IV), which inhibits gastric secretion, did not change the level of feed or water intake, or alter the temporal relationship between eating and drinking. Gastric infusions of 0.15 M HCl (5 ml.kg-1.h-1) did not increase drinking. Pentagastrin infusion (0.05 microgram.kg-1.min-1) increased water intake in some, but not all pigs during a 1-hour infusion. Plasma protein levels increased significantly during 1-hour pentagastrin infusions (0.05 microgram.kg-1.min-1), indicating an estimated fall in blood volume of 2.5%. Captopril (1.75 mg/kg IV), which blocks the renin-angiotensin system, abolished pentagastrin-stimulated drinking. It was concluded that gastric secretion does not play a direct role in normal, periprandial drinking but that in pigs the renin-angiotensin system is involved in pentagastrin-stimulated drinking.