Metabolism of arachidonic acid by pancreatic acini: Relation to amylase secretion

Isolated guinea pig pancreatic acini were incubated with exogenous [¹⁴C]arachidonic acid (10 μM) at 37°C for 3 min. The lipids were extracted and separated by thin-layer chromatography. Radiolabeled metabolites were identified by comigration with standards: 0.024% of the recovered radioactivity comigrated with prostaglandin E₂ (PGE₂), 0.016% comigrated with PGF₂[α], 4.9% was incorporated into triglycerides, 1.8% was incorporated into phospholipids, and 93.2% remained as arachidonic acid. The synthesis of PGE₂ and PGF₂[α] was inhibited by indomethacin (ID₅₀, 30 nM). Simultaneous addition of carbachol or caerulein with the [¹⁴C]arachidonic acid did not alter the metabolism of the arachidonate metabolites in the secretion of amylase. Exogenously added PGE₂ and PGF₂[α] (0.3-100 μM) did not induce amylase secretion from isolated acini. Incubation of isolated acini with indomethacin (0.1-28 μM) did not inhibit the release of amylase induced by carbachol or caerulein. From these data, we conclude that isolated guinea pig pancreatic acini are capable of converting a small percentage of exogenous arachidonate to PGE₂ and PGF₂[α]. However, there is no evidence for a role of these compounds in stimulus-secretion coupling.