Prostaglandin synthesis and metabolism in isolated pancreatic islets of the rat

Isolated pancreatic islets of Langerhans of the rat which were sonicated and incubated with radiolabeled arachidonic acid for 1 hr synthesized several species of prostaglandins (PGs). Both thin-layer and high-performance liquid (HPLC) chromatographic techniques demonstrated the synthesis by islet sonicates of PGF_2α and PGE₂ equivalents, in addition to the 15-keto-13, 14-dihydro metabolites of these primary PGs. In addition, HPLC allowed the identification of 6-keto-PGF_1α (the metabolite of prostacyclin) as a major PG synthesized from arachidonate by this tissue. Islet vascular elements, as well as endocrine cells, may contribute to the synthesis of the latter compound. Lesser amounts of arachidonate were incorporated into PG-like compounds eluting as thromboxane. The synthesis of PGs was sensitive to the protein concentration of islet sonicate, and a five-fold dilution of protein resulted in a comparable reduction in arachidonate incorporation into PGs. Labeled arachidonate was also incorporated into compounds which elute as hydroxy or hydroperoxy-eicosatetrainoic acids on HPLC. Thus, isolated pancreatic islets synthesize a variety of PGs which may have a physiological role in hormone secretion form this endocrine organ.