The effects of prostaglandins on secretion of glucagon and inselin by the perfused rat pancreas

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Abstract
The secretion of both glucagon and insulin by the isolated perfused rat pancreas was significantly stimulated by 10-7 M PG[prostaglandin]H2. Experiments to show that the stimulated secretion was mediated by conversion of PGH2 to TX[thromboxane]A2 or TXB2 revealed no correlation between the amount of secretion and the amount of thromboxane formed. Conversion of PGH2 with a crude platelet thromboxane synthase preparation caused a progressive loss of ability to secrete insulin,, whereas the capacity to stimulate release of glucagon remained at about 1/2 the maximal level. This relatively stable and selective secretagog action on the .alpha.-cells appeared to be due to the formation of PGD2 by the platelet preparation. Direct administration of PGD2 confirmed this interpretation and showed clearly that this PG is a potent secretagog for glucagon with little activity in stimulating the release of insulin. Results showed high and relatively equal stimulation of secretion by .alpha.- and .beta.-cells with exogenous PGE2, PGF2.alpha. and PGH2, little or no secretion by either cell type with TXA2, TXB2 or PGI2, and a unique selective stimulatory action of PGD2 upon the .alpha.-cell.