RT Journal Article
SR Electronic
T1 Signal Transduction Mechanism(s) Involved in Prostacyclin Production Elicited by Acetylcholine in Coronary Endothelial Cells of Rabbit Heart
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 113
OP 122
VO 282
IS 1
A1 H. Kan
A1 Y. Ruan
A1 K. U. Malik
YR 1997
UL http://jpet.aspetjournals.org/content/282/1/113.abstract
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