Amino acids as in vitro secretogogues of avian pancreatic polypeptide (APP) and insulin from the chicken pancreas

Abstract

The potential for a direct effect of selective amino acids on avian pancreatic polypeptide (APP) and insulin secretion was investigated using a system of perifused microfragments of chicken pancreas. Leucine, isoleucine, phenylalanine, and valine produced a sustained increase in APP release when each was evaluated at 5-m M concentrations; 15 m M arginine also produced a sustained increase in APP secretion. The secretory response differed among the amino acids such that 5 m M leucine and isoleucine produced a transitory increase in insulin secretion while lysine, phenylalanine, and arginine produced a sustained increase in insulin secretion. In general, APP secretion exhibited a greater maximal response and a lower threshold for stimulation by various amino acids in vitro than did insulin. The significance of this effect is somewhat unclear due to the failure of intravenous arginine or leucine to alter circulating levels of APP in vivo. In conclusion, amino acids directly increase APP secretion from the chicken pancreas in vitro; although they are relatively unresponsive to glucose, perifused chicken B cells respond to amino acids as do B cells from mammalian species.