Endocrine secretion of alpha-amylase by the pancreas

The effect of the gastrointestinal hormone, cholecystokinin-pancreozymin (CCK-PZ), on the flux of alpha-amylase across the basolateral surface of the pancreas into interstitial fluid was measured by following its appearance in the medium bathing whole rabbit pancreas in organ culture. CCK-PZ increased the rate of amylase release by about an order of magnitude for the maximum applied dose. The response was only observed at concentrations of CCK-PZ that were supramaximal for ductal enzyme secretion (320 pmol/l to 10 nmol/l). Over this range, amylase secretion into the bath varied widely with dose, whereas that into the duct remained relatively unchanged. These observations, in conjunction with others, suggest that the acinar cell, and not the duct system, is the direct source of this amylase and that there is a natural secretion of digestive enzyme from the acinar cell in the endocrine direction that is augmented by CCK-PZ or a homologous peptide.