ACh-induced calcium transients in primary cultures of rabbit aortic endothelial cells.
Acetylcholine (ACh) causes vascular smooth muscle relaxation by releasing endothelium-derived relaxing factor (EDRF) from endothelial cells (EC). Although a pivotal role for cytosolic free Ca2+ ([Ca2+]i) has been implicated in the generation and/or release of EDRF by various agonists, there is no conclusive evidence showing that ACh increases [Ca2+]i in EC. In the present study, using the Ca2+-sensitive fluorescent indicator fura-2, we show for the first time that ACh (10(-5) M) increases [Ca2+]i six- to sevenfold above prestimulus levels in primary cultures of rabbit aortic EC (RbAEC). ACh effects are dose dependent [effective concentration producing 50% of the maximum response (EC50) approximately 9 X 10(-7) M] and are blocked by atropine, a selective muscarinic receptor antagonist. The [Ca2+]i increase is due both to the mobilization of intracellular Ca2+ and to the influx of extracellular Ca2+. A 5-min incubation of RbAEC with 4 beta-phorbol 12-myristate 13-acetate (10(-7) M) inhibits ACh-induced [Ca2+]i transients, suggesting that the signaling pathway involved in ACh receptor signal transduction may be modulated via protein kinase C. These cultured EC provide a unique in vitro model system for studying mechanisms involved in ACh-induced EDRF release.
Danthuluri
N R
NR
Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts.
Cybulsky
M I
MI
Brock
T A
TA
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism; D001572:Benzofurans; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D005456:Fluorescent Dyes; D016257:Fura-2; D007700:Kinetics; D008297:Male; D011817:Rabbits; D013050:Spectrometry, Fluorescence / Q000379:methods; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D001572:Benzofurans; D005456:Fluorescent Dyes; D000109:Acetylcholine; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; D016257:Fura-2