Insulin, pancreatic polypeptide, and glucagon release from the chicken pancreas in vitro: Responses to changes in medium glucose and free fatty acid content

Abstract

The effects of glucose and fatty acids on release of insulin, pancreatic polypeptide (APP), and glucagon by the chicken pancreas were investigated in vitro. Small fragments of chicken pancreas were perifused; pancreatic hormones were measured in the effluent perifusate by radioimmunoassay. Elevation of medium glucose from 200 mg/dl to 500 mg/dl did not affect insulin release while elevation to 700 mg glucose/dl produced a sustained increase in insulin output. Glucagon release was consistently suppressed when glucose was elevated to either level. Pancreatic polypeptide secretion was not reduced by increases in medium glucose. Butyrate and valerate (5 m M) did not affect output of any of the hormones measured. Oleate and linoleate (0.3 and 1.0 m M, respectively) both stimulated insulin secretion; linoleate also stimulated APP and glucagon secretion. None of the fatty acids tested directly reduced glucagon or APP output although partial antagonistic effects of the fatty acids on pancreatic secretion were suggested by “off response” increases in the pancreatic hormone output upon removal of the long-chain fatty acids from the perifusion medium.