Blocking effects of verapamil on pancreatic exocrine secretion induced by dopamine in the dog

The effects of verapamil on the dopamine-induced pancreatic exocrine secretion were investigated in the isolated and blood-perfused canine pancreas at a constant flow rate in situ. All drugs were given intra-arterially. Dose-related increases in the volume of pancreatic secretion induced by dopamine (1-10 micrograms) were reduced by infusion of 50 and 100 micrograms/min of verapamil, but were not affected by diltiazem (100 micrograms/min) and dilazep (100 micrograms/min) infusions. Protein concentration in pancreatic juice induced by dopamine was decreased significantly by the infusion of verapamil, diltiazem and dilazep, but bicarbonate concentration was not. These results suggest that verapamil reduced the dopamine-induced pancreatic secretion by virtue of its dopamine antagonist activity and inhibited protein secretion by virtue of its calcium channel blocking action.