Glucose-induced phospholipid hydrolysis in isolated pancreatic islets: quantitative effects on the phospholipid content of arachidonate and other fatty acids

摘要: Abstract Our recent findings indicate that glucose-induced insulin secretion from isolated pancreatic islets is temporally associated with accumulation of substantial amounts free arachidonic acid and arachidonate may serve as a second messenger for intracellular calcium mobilization in islets. In an effort to determine the source this released arachidonate, endogenous fatty composition phospholipids has been determined by thin-layer chromatographic separation phospholipids, methanolysis methyl esters, quantitative gas analyses. The relative abundance judged their content was phosphatidylcholine (PC), 0.63; phosphatidy-lethanolamine (PE), 0.23; phosphatidylinositol (PI), 0.067; phosphatidylserine (PS), 0.049. Arachidonate constituted 17% total islet content, PC contained 43% arachidonate. Islets incubated [3H]arachidonate presence 28 mM d -glucose incorporated radiolabel into considerably higher specific activity than PE, PS or PI. glucose 30 min significantly lower 3 glucose, smaller effects were observed molar decrement 3.2 pmol/islet under these conditions, which sufficient account previously (2 pmol/islet). A sensitive method involving negative ion-chemical ionization-mass spectrometric analyses pentafluorobenzyl esters acids derived trace lysophosphatidylcholine (lyso-PC) developed, glucose-stimulation found reduce lyso-PC about 10-fold. These secretagogue induces phospholipid hydrolysis suggest be major accumulates glucose-stimulated