title: Possible role of endogenous prostaglandins in glucagon secretion by isolated guinea-pig islets.
abstract: Previous studies have demonstrated that prostaglandins stimulate glucagon secretion in vitro and in vivo. The present work was aimed at investigating the influence of two inhibitors of prostaglandin synthesis, isopropyl-2 nicotinoyl-3 indole (L8027) and indomethacin, on basal and arginine- or noradrenaline-stimulated glucagon release from isolated guinea-pig islets incubated in the absence of glucose. L8027 (10(-4) and 10(-5) mol/l) did not alter basal glucagon release, blocked almost completely the glucagon response to arginine (10(-2) mol/l), had no effect on the glucagon release induced by noradrenaline (10(-4) mol/l), but reduced the stimulatory effect of a lower concentration of noradrenaline (5.10(-7) mol/l). The kinetic study of this inhibitory effect demonstrated that (1) it necessitates preincubation of the islets with L8027 for 30 minutes before the addition of arginine, (2) after a short preincubation period (30 minutes) in the presence of L8027, removal of the inhibitor at the time of arginine stimulation resulted in enhanced glucagon response, (3) on the contrary, after a prolonged incubation period (75 min) with arginine and L8027, the inhibitory effect remained transiently detectable after removal of L8027. Indomethacin similarly blocked arginine- and noradrenaline-induced glucagon secretion. These results suggest that an intra-insular synthesis of prostaglandins is involved in the A cell response to arginine and noradrenaline.
mesh_terms: D000818:Animals; D001120:Arginine / Q000494:pharmacology; D005934:Glucagon / Q000378:metabolism*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007515:Islets of Langerhans / Q000378:metabolism*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D011448:Prostaglandin Antagonists / Q000494:pharmacology*; D011453:Prostaglandins / Q000494:pharmacology*
chemical_list: D011448:Prostaglandin Antagonists; D011453:Prostaglandins; D005934:Glucagon; D001120:Arginine; D009638:Norepinephrine; D007213:Indomethacin