Amylase secretion from dispersed human pancreatic acini: Neither cholecystokinin A nor cholecystokinin B receptors mediate amylase secretion in vitro

Introduction: In humans, cholecystokinin (CCK) stimulates pancreatic secretion, and CCK-A receptor antagonists prevent it in vivo. However, the human pancreas has been reported to express mainly CCK-B receptors. Aim: To elucidate this discrepancy. Methodology: We prepared dispersed acini from human pancreas and examined whether various doses of CCK stimulated the release of amylase, in comparison with the effects of neuromedin C, carbamylcholine, and secretin. Results: Human pancreatic acini did not respond to any dose of CCK or secretin. Amylase release was stimulated by carbamylcholine and neuromedin C dose-dependently and was inhibited by respective antagonists. The localizations of CCK receptors in the human duodenum were determined. High concentrations of CCK-A receptors were detected in the mucosa as well as in smooth muscle of the duodenum by microautoradiography. Conclusion: In conclusion, human pancreatic acinar cells are responsible for carbamylcholine and neuromedin C but not for secretin. Neither CCK-A nor CCK-B receptor mediates amylase release from human pancreatic acini in vitro. Pancreatic secretion in humans in vivo may be regulated indirectly by CCK (via CCK-A receptors).