Endothelin-1 increases intracellular calcium mobilization but not calcium uptake in rabbit vascular smooth muscle cells.
Conflicting evidence has been reported regarding the role of endothelin-1, a potent vasconstrictor peptide, in stimulating extracellular calcium influx in rabbit vascular smooth muscle. The objective of this study was to elucidate the effects of endothelin-1 on transmembrane 45Ca2+ influx and intracellular calcium mobilization in cultured rabbit aortic smooth muscle cells. In calcium containing buffer, endothelin-1 induced a concentration-dependent 45Ca2+ efflux response over the range of 10 pM to 100 nM with an EC50 of approximately 60 pM. Maximum endothelin-stimulated 45Ca2+ efflux was not affected by the absence of extracellular calcium or the presence of 1 microM verapamil. Endothelin-1 did not induce transplasmalemmal 45Ca2+ uptake at times up to 30 min. These findings suggest that an alteration in intracellular calcium handling, rather than extracellular calcium influx, is responsible for the endothelin-stimulated increase in intracellular calcium concentration in rabbit aortic smooth muscle cells.
Bialecki
R A
RA
Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115.
Izzo
N J
NJ
Colucci
W S
WS
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D016232:Endothelins; D004730:Endothelium, Vascular / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D010455:Peptides / Q000494:pharmacology*; D011817:Rabbits; D014700:Verapamil / Q000494:pharmacology
D016232:Endothelins; D010455:Peptides; D014700:Verapamil; D002118:Calcium