Pancreatic bicarbonate, serum gastrin, and secretin responses to meals varying in pH

1977.-The role of secretin in the postprandial bicarbonate response by the pancreas is not clear. This study reports secretin and bicarbonate secretion afier exogenous and endog-enous acidification of meal. In dogs with gastric and pan-creatic fistulas, a liver extract meal at various pH levels was introduced into the stomach and kept at the preselected pH by intragastric titration. Gastric acid, pancreatic bicarbonate, serum gastrin, and plasma secretin were measured. The meal at pH 7 produced an increase of gastrin levels of 230 % above basal and a gastric acid output from a basal of 0.8-16.9 meq/30 min. Acidification of the meal evoked a pH-dependent reduc-tion of gastrin and gastric acid secretion, a PI&dependent elevation of pancreatic bicarbonate, and significant elevation of secretin at pH 3 (43 % above basal) and at pH 2 (80 % above basal). Postprandial endogenous acidification of a meal, with