INCREASE IN LYSOPHOSPHATIDYLETHANOLAMINE IN THE CELL-MEMBRANE UPON THE REGULATED EXOCYTOSIS OF PANCREATIC ACINAR AR42J CELLS

A specific cytosolic phospholipase A2 inhibitor, arachidonyl trifluoro methyl ketone (AACOCF(3)), was found to inhibit the regulated exocytos is of pancreatic acinar AR42J cells, When AR42J cells were stimulated with cholecystokinin octapeptide (CCB-8), the regulated exocytosis mon itored by amylase release was rapidly activated and increased by 2.5-f old during one hour, After AR42J cells were treated with AACOCF(3), am ylase release by CCK-8 remained at the basal level, Thus, changes in t he composition of membrane phospholipids before and after stimulation were investigated, Within 1 min after CCK-8 stimulation, lysophosphati dylethanolamine (lysoPE) in the cellular membranes of AR42J was increa sed while lysophosphatidylcholine stayed unchanged, In the presence of AACOCF(3), lysoPE was not increased by CCK-8, Those results indicate that the increment of lysoPE is linked to the regulated exocytosis.