Insulin, prostaglandin E2 and glucagon release by human tissue incubated in vitro. Influence of indomethacin

In view of reports that prostaglandins influence insulin and glucagon secretion, we have studied PGE2, insulin and glucagon release from fragments (15-20 mg) of human insulinoma tissue incubated in vitro in the absence or presence of indomethacin (100 mumol/liter) an inhibitor of prostaglandin synthesis. Acid-ethanol extraction of this tissue showed the following hormonal contents : insulin : 7.17 U and glucagon 84.4 ng per g of tissue (wet weight). In the absence of indomethacin, the mean release of PGE2, insulin and glucagon into the incubation medium was 3.65 +/- 1.3 pmol, 10.5 +/- 1.2 mU and 708.4 +/- 141.8 pg in two hours (mean of 5 vials containing 2 fragments of 15-20 mg of tissue). PGE2 release was significantly inhibited in the presence of indomethacin (0.89 +/- 0.23 pmol). This effect was associated with a significantly higher insulin (16.8 +/- 1.9 mU/2 hours) and lower glucagon (176 +/- 19.7 pg/2 hours) release. These results support the view that insular tissue possesses a prostaglandin synthesis system which positively modulates glucagon secretion whereas it negatively influences insulin release.