Evidence that prostaglandins activate calcium channels to enhance basal and stimulation-evoked catecholamine release from bovine adrenal chromaffin cells in culture.
The effects of prostaglandins (PGs) on catecholamine (CA) secretion and Ca2+ fluxes were studied in a primary culture of bovine chromaffin cells. PGD2, PGF2 alpha and PGE2 induced CA release from cultured bovine chromaffin cells in a concentration dependent manner (0.03-3 microM). PGD2, PGF2 alpha and PGE2 at 3 microM elicited maximum CA release of 0.043 +/- 0.001, 0.059 +/- 0.008, 0.062 +/- 0.002 micrograms/10(6) cells, respectively. Three micromolar of PGD2, PGF2 alpha and PGE2 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 Ca2+-free medium, PGs failed to affect basal and caffeine (50 mM)-induced CA release. PGF2 alpha increased 45Ca uptake and showed additive effect with ACh on 45Ca uptake. Nicardipine (0.1-10 microM) suppressed CA release and 45Ca uptake induced by PGF2 alpha, while diltiazem and verapamil failed to affect these responses to PGF2 alpha. BAY K 8644 (1 microM) potentiated CA release and 45Ca uptake evoked by PGF2 alpha. These results suggest that PGs enhance basal and stimulation-evoked CA release from chromaffin cells possibly through facilitation of Ca2+ influx. The mechanisms of action of PGs in adrenal medulla are discussed.
Koyama
Y
Y
Department of Pharmacology, Hiroshima University School of Dentistry, Japan.
Kitayama
S
S
Dohi
T
T
Tsujimoto
A
A
D000109:Acetylcholine / Q000494:pharmacology; D000313:Adrenal Medulla / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects*; D011453:Prostaglandins / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D002395:Catecholamines; D007473:Ion Channels; D011453:Prostaglandins; D000109:Acetylcholine; D002118:Calcium