Effects of verapamil on exocrine pancreatic secretion in man

Calcium ions are thought to mediate hormonal and cholinergic stimulation of exocrine pancreatic secretion. In order to further eludicate the role of calcium ions in stimulus-secretion coupling of the pancreas, the effect of the calcium antagonist verapamil, which inhibits transmembrane calcium influx, was studied on pancreatic secretion in 35 healthy male volunteers. Every subject had two stimulation periods of 2 hr each with a 3-hr period between the two. Pancreatic secretion was stimulated by cholecystokinin in 12 subjects, by secretin in 14 subjects, and by sham feeding in 6 subjects. Three subjects were studied without any secretory stimulus. Verapamil as an intravenous bolus of 150 micrograms/kg followed by an intravenous infusion of 150 micrograms/kg/hr or saline were given during the two 2-hr stimulation periods in a randomized order. The pancreatic secretory responses to stimulation by cholecystokinin, secretin, or sham feeding, as well as the basal pancreatic secretion without a secretory stimulus were left unaffected by verapamil when compared to the saline control. The results, therefore, call into question the hypothesis that transmembrane calcium influx is a major mediator of pancreatic secretion in response to hormonal or cholinergic stimulation in man.