Prostanoid responses of bovine adrenal medullary cells: lack of effect of opioids.

The effects of opioid compounds on catecholamine (CA) secretion and phosphatidylinositol turnover induced by prostaglandins E1 (PGE1) and E2 (PGE2) in cultured bovine adrenal medullary cells have been studied. PGE1 induced CA secretion at 100 nM and above. PGE2 was more potent, inducing CA secretion at 1-10 nM. Both prostaglandins required extracellular calcium to induce CA release. Neither etorphine nor diprenorphine (1 nM-10 microM) affected CA secretion induced by 1 microM PGE1 or 0.1 microM PGE2. PGE1 a small increase in phosphatidylinositol turnover at 10 microM, but had no effect at lower concentrations. PGE2 was effective at 1 and 10 microM. Etorphine and diprenorphine had no effect on phosphatidylinositol turnover induced by PGE1 or PGE2. The results indicate prostaglandins can facilitate CA secretion independently of their effects on phosphatidylinositol metabolism. They also indicate that endogenous adrenal opioid peptides do not act on the opioid binding sites found on adrenal medullary cells to modify their responses to prostaglandins.