Evidence that prostaglandins activate calcium channels to enhance basal and stimulation-evoked catecholamine release from bovine adrenal chromaffin cells in culture

Abstract

The effects of prostaglandins (PGs) on catecholamine (CA) secretion and Ca 2+ fluxes were studied in a primary culture of bovine chromaffin cells. PGD 2, PGF 2α and PGE 2 induced CA release from cultured bovine chromaffin cells in a concentration dependent manner (0.03–3 μM). PGD 2, PGF 2α and PGE 2 at 3 μM elicited maximum CA release of 0.043 ± 0.001, 0.059 ± 0.008, 0.062 ± 0.002 μg/10 6 cells, respectively. Three micromolar of PGD 2, PGF 2α and PGE 2 enhanced CA release induced by acetylcholine (ACh) in a degree of 186 ± 10, 206 ± 6, 150 ± 4% of control respectively. PGs also enhanced CA release induced by 20 mM K +, veratridine and A23187. In Ca 2+-free medium, PGs failed to affect basal and caffeine (50 mM)-induced CA release. PGF 2α increased 45Ca uptake and showed additive effect with ACh on 45Ca uptake. Nicardipine (0.1–10 μM) suppressed CA release and 45Ca uptake induced by PGF 2α, while diltiazem and verapamil failed to affect these responses to PGF 2α. BAY K 8644 (1 μM) potentiated CA release and 45Ca uptake evoked by PGF 2α. These results suggest that PGs enhance basal and stimulation-evoked CA release from chromaffin cells possibly through facilitation of Ca 2+ influx. The mechanisms of action of PGs in adrenal medulla are discussed.