Effect of sham feeding and acute suppression of acid secretion on human gastric lipase secretion

Objective: Gastric lipase and gastric acid are secreted simultaneously. The aim of this study was to investigate whether the acid interferes with the lipase secretion, Thr: secretion of human gastric lipase was studied during blockade of gastric acid secretion and modified sham feeding to estimate the impact of these conditions on bath gastric lipase enzyme activity and immunoreactivity, Methods: Eight healthy volunteers were intubated with a nasogastric tube. We examined gastric aspirates for the amount and activity of lipase secretion during basal conditions, after blockade of acid secretion with a proton pump inhibitor (orneprazole i.v. infusion), and in response to sham feeding (chewing gum) during the blockade. Results: The amount of secreted gastric lipase was unaffected by blockade of acid secretion and increased significantly after sham feeding (169.9 +/- 35.7 mu g/15 min to 348.1 +/- 79.2 mu g/15 min; p < 0.01). Like wise, the output of enzyme activity increased after sham feeding (0.63 +/- 0.09 kU/15 min to 1.52 +/- 0.36 kU/15 min; p < 0.03). The concentration of enzyme activity remained unchanged by blockade of acid secretion, whereas the output of enzyme activity was decreased, probably because of reduced volume secretion or denaturation and conformational changes of the enzyme. Plasma concentrations of gastrin increased in response to blockade of acid secretion (basal 9.6 +/- 1.4 pmol/L to 13.3 +/- 2.9 pmol/L; p < 0.02), Conclusions: Gastric acid secretion is mat a prerequisite for gastric lipase secretion, Lipase enzyme activity, though, is sensitive to anacidic conditions. (C) 1998 by Am. Coll. of Gastroenterology.