Basal calcium entry in vascular smooth muscle
Basal calcium entry in vascular smooth muscle
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DOI：
10.1016/j.ejphar.2004.09.060
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发表时间：
2004-11-28
影响因子：
5
通讯作者：
Ruegg, UT
中科院分区：
文献类型：
--
作者：
Poburko, D;Lhote, P;Ruegg, UT
Basal calcium leak into smooth muscle was identified 30 years ago yet remains poorly understood. We characterized this leak measuring Ca-45(2+) uptake into cultured rat aortic smooth muscle cells. Wash solution (0 degreesC) containing lanthanum (3 mM) removed extracellular tracer and increased cellular Ca-45(2+) retention more effectively than EGTA (0.2 mM). Basal Ca2+ entry was 1.45x10(9) Ca2+ (.) cell(-1) (.) min(-1). This translated to similar to250 mumol(-1) (.) min(-1) given cell volumes of 4-15 pl as determined by 3-D image reconstruction. Gadolinium (100 muM) blocked 80% of the leak and exhibited a biphasic concentration-response relation (IC(50)s=1 muM and 2 mM). Organic ion channel blockers also inhibited similar to80% of the leak; 45% by nifedipine (10 muM), 7% was exclusively blocked by SKF 96365 (1-[b-[3-(4-Methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole) (50 muM) and 23% was exclusively sensitive to 2-aminoethoxydiphenylborate (2-APB, 75 muM). Reverse transcriptase polymerase chain reaction revealed TrpCl, 4 and 6 mRNA, and we propose that 2APB may selectively block TrpC4-containing channels. We conclude that basal Ca2+ entry is mainly due to a basal open probability of excitable Ca2+-channels. (C) 2004 Elsevier B.V. All rights reserved.
