Lysophosphatidylinositol, but not lysophosphatidic acid, stimulates insulin release. A possible role for phospholipase A2 but not de novo synthesis of lysophospholipid in pancreatic islet function.

In the current study, lysophosphatidylinositol is shown to promote insulin release in a manner having characteristics of physiologic exocytosis--that is, it is dose-dependent, saturable, reversible, inhibitable and unassociated with detrimental effects on subsequent islet functioning. Lysophosphatidylglycerol had similar insulinotropic effects. However, lysophosphatidic acid was ineffective over a wide range of concentrations. These studies provide further support for the postulated role of phospholipase A-generated lysophospholipids in signal transduction in the pancreatic islet but suggest that any de novo synthesis of lysophosphatidic acid from metabolites of glucose (M. Dunlop and R. Larkins, Biochem. Biophys. Res. Comm. 132:467, 1985) is unlikely to contribute directly to the insulin secretion induced by that fuel.