Effect of divalent cations on gastrointestinal hormone release and exocrine pancreatic secretion in dogs

Abstract

The purpose of this study was to examine the effect of three common divalent cations (Ca2+, Mg2+, and Zn2+) on the release of cholecystokinin (CCK-33), pancreatic polypeptide (PP), and gastrin. Five dogs with pancreatic and gastric fistulas were given 1-h intraduodenal infusions of calcium (5 mmol X kg-1 X h-1), magnesium (4 mmol X kg-1 X h-1), or zinc (1 mmol X kg-1h-1). At another time the same dogs were given an intravenous bolus followed immediately by a 1-h infusion of calcium (0.36 mmol/kg [bolus], 0.36 mmol X kg-1 X h-1), magnesium (0.25 mmol/kg [bolus], 0.25 mmol X kg-1 X h-1), or zinc (0.03 mmol/kg [bolus], 0.03 mmol X kg-1 X h-1). Intraduodenal infusions of calcium, magnesium, and zinc significantly stimulated CCK-33, PP, and gastrin release. Intravenous calcium stimulated CCK-33, PP, and gastrin release to 245, 193, and 155% of basal levels, respectively. Intravenous magnesium increased CCK-33 to 123% of basal levels but did not stimulate PP and gastrin levels. Intravenous zinc stimulated release of CCK-33, PP, and gastrin to 126, 185, and 124%, respectively. This study shows that calcium, magnesium, and zinc can stimulate release of CCK-33, PP, and gastrin in much the same manner. We suggest that these cations may have a nonspecific electrical action that results in an alteration of membrane permeability, which leads to release of gastrointestinal hormones.