Mg2+ and caffeine-induced intracellular Ca2+ release in human vascular endothelial cells.
Interaction of ionized magnesium ([Mg2+]o) and caffeine in regulation of intracellular free calcium concentration ([Ca2+]i) in human aortic endothelial cells was studied using fura-2 and digital imaging microscopy. In 1.2 mM [Mg2+]o, basal [Ca2+]i was 73.7 +/- 22.4 nM, with a heterogeneous distribution within the cells. No significant changes of basal [Ca2+]i were found either when cells were treated with 10 mM caffeine or when [Mg2+]o was lowered from 1.2 mM to 0.3 mM. However, a combined superfusion of the cells with 0.3 mM [Mg2+]o and 10 mM caffeine resulted in a significant elevation of [Ca2+]i to 382.8 +/- 57.1 nM, probably by release of Ca2+ from internal stores, which was attenuated by NiCl2 (1 mM). These results suggest that a Ca(2+)-induced Ca2+ release mechanism is involved in regulation of [Ca2+]i in endothelial cells, which may be either regulated or modulated by Mg2+.
Zhang
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A
Department of Physiology, State University of New York, Brooklyn 11203.
Cheng
T P
TP
Altura
B T
BT
Altura
B M
BM
D001011:Aorta / Q000166:cytology / Q000378:metabolism; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016257:Fura-2; D006801:Humans; D008274:Magnesium / Q000494:pharmacology*
D002110:Caffeine; D008274:Magnesium; D002118:Calcium; D016257:Fura-2