STIMULATION BY PROSTAGIANDIN E2 OF GLUCAGON AND INSULIN RELEASE FROM ISOLATED RAT PANCREAS

To ascertain whether prostaglandins (PG) may play a role in the secretion of glucagon and in an attempt to elucidate the conflicting observations on the effects of PG on insulin release, the isolated in-tact rat 5 ancreas was perfused with solutions containing 1.1 x 10sg to 1.8 x lo- M PGE2. In the presence of 5.6 mM glucose significant in-crements in portal venous effluent levels of glucagon and insulin were observed in response to minimal concentrations of 2.8 x 10-8 and 1.4 x lo-%l PGE2, respectively; a dose-response relationship was evident for both hormones at higher concentrations of PGE2. When administered over 60 seconds, 1.4 x lo-6M PGE2 resulted in a significant increase in glucagon levels within 24 seconds and in insulin within 48 seconds. Ten-minute perfusions of 1.4 x 10m6M PGE2 elicited biphasic release of both islet hormones; Phase I glucagon release preceded that of insulin. Both phases of the biphasic glucagon and insulin release which occur-red in response to 15-minute perfusions of 10 mM arginine were aug-mented by PGE2. cagon and These observations indicate that PGE2 can evoke glu-insulin release at concentrations close to those observed by others in the extracts of rat pancreas. We conclude that PG may be involved in the regulation of secretion of glucagon and insulin and may mediate and/or modify the pancreatic islet hormone response to other secretagogues. ACKNOWLEDGEMENTS PGE2 was a gift of Dr. John Pike of the Upjohn Company, Kalamazoo, MI. The radioimmunoassays of glucagon and insulin were performed with the skillful technical assistance of Mrs. S. Grauds and Mssrs. G