Twenty-four-hour collections of gastric content in spider monkeys

Abstract

Hourly collections of fasting gastric content were made from six spider monkeys and two macaques with chronic gastric fistulae under conditions which allowed the animals free movement except during the collection period. A rise in pH was observed in 13 of 14 experiments after 6 pm while a return to a pH of 1–2 was seen in nine experiments between 7 and 8 AM the next morning. In two monkeys, each studied on three occasions, there was a significant decrease in volume and acid concentration coincident with the rise in pH. Pepsin concentrations did not change significantly. The electrolyte composition of samples with a pH of 7 or above and a chloride concentration of over 90 mEq/liter, was similar to that of the contents of a vagally-innervated pouch during the night except that the potassium concentration was twice as great in the fistula content. Pouch contents during feeding showed considerable acid secretion. The pH of the fasting gastric content of two macaques was greater than 3 over a 24-hr period.