PT  - JOURNAL ARTICLE
AU  - Kan, H.
AU  - Ruan, Y.
AU  - Malik, K. U.
TI  - Signal Transduction Mechanism(s) Involved in Prostacyclin Production Elicited by Acetylcholine in Coronary Endothelial Cells of Rabbit Heart
DP  - 1997 Jul 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 113--122
VI  - 282
IP  - 1
4099  - http://jpet.aspetjournals.org/content/282/1/113.short
4100  - http://jpet.aspetjournals.org/content/282/1/113.full
SO  - J Pharmacol Exp Ther1997 Jul 01; 282
AB  - The purpose of this study was to elucidate the mechanism by which acetylcholine (ACh) promotes prostacyclin (PGI2) production in cultured coronary endothelial cells (CEC) of the rabbit heart. ACh-induced production of PGI2, measured as immunoreactive 6-keto-PGF1 α, was enhanced by increasing the extracellular calcium (Ca++) concentration and reduced by Ca++ depletion. The receptor-operated Ca++channel blocker SK&F96365, but not the voltage-dependent Ca++ channel blockers verapamil or nifedipine, attenuated ACh-induced 6-keto-PGF1 α production and the associated rise in cytosolic Ca++. Thapsigargin, which depleted Ca++ accumulation from the intracellular Ca++ store, did not prevent the ACh-induced rise in cytosolic Ca++. In the absence of extracellular Ca++, ACh and ATP increased cytosolic Ca++ but did not alter 6-keto-PGF1 α production. In permeabilized CEC, guanosine 5′-O-(3-thiotriphosphate) (GTP-γ-S) but not ACh enhanced 6-keto-PGF1 α synthesis. ACh increased 6-keto-PGF1 α production in the presence of GTP-γ-S. These effects of GTP-γ-S were attenuated by guanosine 5′-O-(2-thiotriphosphate). In the absence of extracellular Ca++, ACh or ATP increased cytosolic Ca++ in cells permeabilized with β-escin and loaded with GTP-γ-S; this effect was attenuated by guanosine 5′-O-(2-thiotriphosphate). The effect of ATP but not ACh to mobilize intracellular Ca++ or increase 6-keto-PGF1 α was inhibited by pertussis toxin. The phospholipase C inhibitor D609, which attenuated ACh- and ATP-induced mobilization of intracellular Ca++, did not alter 6-keto-PGF1 α production. The NO synthase inhibitor N-monomethyl-arginine also failed to alter ACh-induced 6-keto-PGF1 α synthesis. These data suggest that, in CEC of the rabbit heart, ACh stimulates prostacyclin production via a pertussis toxin-insensitive G protein and by increasing the influx of extracellular Ca++ through a G protein-independent receptor-operated Ca++ channel. The American Society for Pharmacology and Experimental Therapeutics