Abstract
1 The effects of three methylene analogues of adenosine 5'-triphosphate (ATP) or 5'-diphosphate (ADP) have been studied on insulin secretion from the isolated perfused pancreas of the rat: 5'-adenylmethylene diphosphonate or beta, gamma-methylene ATP, adenosine 5'-alpha, beta-methylene triphosphate or alpha, beta-methylene ATP and adenosine 5'-alpha, beta-methylene diphosphonate or alpha, beta-methylene ADP. 2 beta, gamma-Methylene ATP did not elicit any increase of insulin release: alpha, beta-methylene ATP and alpha, beta-methylene ADP induced a biphasic stimulation of insulin secretion; this effect was dose-related between 1.65 and 165 mumol/l. Relative potency ATP/alpha, beta-methylene ATP was 1.2 and ATP/alpha, beta-methylene ADP was 0.31. 3 Our results point to the importance of the steric and electronic characteristics of the polyphosphate chain of the analogues of ATP and ADP in inducing an insulin secretory effect. They support the hypothesis of a purine receptor for ATP and ADP.