Effect of papaverine on pancreatic exocrine secretion in the dog

The effect of papaverine on the secretion of pancreatic juice in the dog was investigated in preparations of isolated, blood-perfused pancreas. Small doses of papaverine (1-30 microgram) injected intra-arterially did not induce any secretory action. Relatively large doses of papaverine (0.1-1 mg) caused dose-dependent increases in the secretion of pancreatic juice after a delay of a few minutes. The secretory activity of 1 mg of papaverine was approximately equal to that of 0.06 units of secretin. The concentration of bicarbonate in the pancreatic juice induced by papaverine was increased. However, protein concentration was increased slightly. This effect is analogous to that of secretin. Papaverine-induced secretion was not modified by pretreatment with phentolamine, propranolol, atropine, guanethidine and haloperidol. On the other hand, papaverine significantly potentiated the secretion of pancreatic juice induced by secretin. From these results, it is concluded that large doses of papaverine may produce an increase in pancreatic secretion mediated through the increase of intracellular cyclic AMP concentration.