Increase in Lysophosphatidylethanolamine in the Cell Membrane upon the Regulated Exocytosis of Pancreatic Acinar AR42J Cells

Abstract

A specific cytosolic phospholipase A2 inhibitor, arachidonyl trifluoromethyl ketone (AACOCF₃), was found to inhibit the regulated exocytosis of pancreatic acinar AR42J cells. When AR42J cells were stimulated with cholecystokinin octapeptide (CCK-8), the regulated exocytosis monitored by amylase release was rapidly activated and increased by 2.5-fold during one hour. After AR42J cells were treated with AACOCF₃, amylase release by CCK-8 remained at the basal level. Thus, changes in the composition of membrane phospholipids before and after stimulation were investigated. Within 1 min after CCK-8 stimulation, lysophosphatidylethanolamine (lysoPE) in the cellular membranes of AR42J was increased while lysophosphatidylcholine stayed unchanged. In the presence of AACOCF₃, lysoPE was not increased by CCK-8. Those results indicate that the increment of lysoPE is linked to the regulated exocytosis.