AMYLASE ACTIVITY IN PANCREATIC-ISLET CELLS

Amylase activity was measured in homogenates of rat whole pancreas, is olated islets and purified islet beta and non-beta islet cells. The sp ecific activity of the enzyme, as expressed relative to protein conten t, was 25 times higher in the pancreas than in islets and not vastly d ifferent in islets and purified beta-cells. No sizeable amylase activi ty was found in purified non-beta cells. In sections of rat pancreatic tissue, immunocytochemistry documented the presence of amylase-like m aterial in acinar cells and islet beta-cells and its virtual absence i n non-beta islet cells. These findings were confirmed in dispersed isl et cells also examined by double immunofluorescence of alpha-amylase a nd either insulin or glucagon. The unexpected presence of amylase acti vity in islet beta cells is considered in the perspective of both thei r ontogeny and the metabolism of glycogen in these cells.