Inhibitory effects of pirenzepine on cholecystokinin and secretin stimulation on exocrine and endocrine rat pancreas.

Effects of pirenzepine, a newly developed anticholinergic drug, on exocrine and endocrine pancreatic functions stimulated by cholecystokinin octapeptide and secretin were studied in both isolated pancreatic acini and the isolated perfused pancreas of rats. In the isolated acini, pirenzepine did not have any significant effect on cholecystokinin-induced amylase release but caused an inhibition of amylase secretion initiated by secretin and shifted the dose-response curve for amylase secretion to the right. In the isolated perfused pancreas stimulated with 100 pM cholecystokinin octapeptide, addition of 10 microM pirenzepine before as well as after 20 min of perfusion significantly inhibited pancreatic juice flow but not enzyme output. In contrast, pirenzepine caused an inhibition of secretin-stimulated enzyme secretion, but not pancreatic juice flow. The stimulatory effect of both cholecystokinin octapeptide and secretin on insulin secretion was also inhibited by pirenzepine. The present data indicate that pirenzepine may have an influence on pancreatic exocrine and endocrine function by inhibiting endogenous cholinergic activity of the pancreas when a large dose is given.