Release of cholecystokinin and exocrine pancreatic secretion in response to an elemental diet in human subjects.

We investigated in human volunteers the effects of an elemental diet (ED) containing amino acids on release of endogenous cholecystokinin (CCK) using a highly sensitive and specific radioimmunoassay of CCK and exocrine pancreatic secretion using a dye dilution technique with polyethylene glycol 4000 as a nonabsorbable marker. Intrajejunal administration of ED at three different infusion rates (12.5, 25, and 50 ml/30 min) resulted in a significant increase in plasma CCK concentration in a dose-related manner. Plasma concentrations of gastrin or secretin, however, did not change. Pancreatic secretion of protein, amylase, and bicarbonate also increased significantly. The change in pancreatic secretion of protein, amylase, and bicarbonate output paralleled that of the circulating CCK level but not that of plasma secretin. Thus, the dose of amino acid contained in ED recommended for clinical use can significantly stimulate the release of CCK from the upper small intestine, raising the plasma concentration of CCK. This level can evoke a significant increase in exocrine pancreatic secretion.