Gastric Acid Does Drive Pancreatic Bicarbonate Secretion

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Abstract
Grossman, M. I. & Konturek, S. J. Gastric acid does drive pancreatic bicarbonate secretion. Scand. J. Gastroent. 1974, 9, 299-302. Earlier studies questioned whether the amount of acid in the duodenum after meals was great enough to stimulate pancreatic secretion. In this study, in dogs with gastric and pancreatic fistulas, a meal of liver was instilled into the gastric fistula, and the pH of the gastric contents was held constant at various levels by continuous intragastric titration. With intragastric pH held at 7.0, pancreatic bicarbonate secretion was low and protein secretion moderate, characteristic of the response to cholecystokinin alone. No augmentation of pancreatic bicarbonate secretion occurred as intragastric pH was lowered from 7.0 to 4.5. Between pH 4.5 and 3.0 bicarbonate secretion rose sharply in response to increasing acidification. Bicarbonate secretion was already near maximal at pH 3.0 and so showed little further increase as pH was lowered to 1.5. Augmentation of pancreatic protein secretion occurred in the same range of pH that caused bicarbonate responses. With a meal held at pH 5.0 by intragastric titration, about 0.4 units/kg-hr of exogenous secretin produced bicarbonate and protein responses equal to those of a natural meal. We conclude that gastric acid plays a major role in driving pancreatic secretion. The small amount of secretin released is highly effective because of the amplifying effect of cholecystokinin released by other constituents of the meal.