Evidence for receptor-mediated bivalent-cation entry in A10 vascular smooth-muscle cells.
In fura-2-loaded A10 vascular smooth-muscle cells, 1 nM-vasopressin and 200 nM-endothelin evoked a rapid transient rise in intracellular free Ca2+ concentration [( Ca2+]i), which was then followed by a maintained elevation of [Ca2+]i. The maintained elevation of [Ca2+]i was only partially inhibited by 5 microM-nifedipine, but completely abolished in the presence of 1 mM-EGTA. When extracellular Ca2+ was replaced with 1 mM-Mn2+ (Mn2+ quenches fura-2 fluorescence), both endothelin and vasopressin evoked an Mn2+ quench of the fluorescence from the intracellularly trapped fura-2, even in the presence of 5 microM-nifedipine. These data suggest that both vasopressin and endothelin promote a bivalent-cation influx and provide further evidence for receptor-mediated Ca2+ entry in vascular smooth muscle.
Simpson
A W
AW
University Laboratory of Physiology, Oxford, U.K.
Stampfl
A
A
Ashley
C C
CC
D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D002413:Cations, Divalent; D002460:Cell Line; D016232:Endothelins; D004730:Endothelium, Vascular; D008345:Manganese / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D009532:Nickel / Q000494:pharmacology; D009543:Nifedipine / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D014667:Vasopressins / Q000494:pharmacology
D015220:Calcium Channels; D002413:Cations, Divalent; D016232:Endothelins; D010455:Peptides; D011956:Receptors, Cell Surface; D014667:Vasopressins; D008345:Manganese; D009532:Nickel; D009543:Nifedipine; D002118:Calcium