Store-operated channels mediate Ca2+ influx and contraction in rat pulmonary artery
Store-operated channels mediate Ca2+ influx and contraction in rat pulmonary artery
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DOI：
10.1161/hh2201.100315
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发表时间：
2001-11-09
影响因子：
20.1
通讯作者：
Gurney, AM
中科院分区：
文献类型：
--
作者：
Ng, LC;Gurney, AM
已提出由Ca 2+库耗竭激活的阳离子通道介导血管平滑肌细胞中的Ca 2+内流。本研究的目的是确定储存操纵的通道在肺动脉平滑肌细胞（PASMCs）中是否具有功能作用。在完整的大鼠肺动脉环，cyclopiazonic酸（CPA）产生了持续的收缩，耐硝苯地平抑制，但取消在Ca 2 +-free溶液和50%的阻断存在下，6 μ mol/L Cd 2+，10 μ mol/L Ni 2+，600 μ mol/L La 3+，和7 μ mol/L SKF 96365。在新鲜分离的PASMCs上，CPA通过刺激二氢吡啶抗性的Ca ~（2+）内流，增加细胞内Ca ~（2+）浓度，10 μ mol/L Ni ~（2+）和7 μ mol/L SKF 96365可阻断Ca ~（2+）内流约50%。在穿孔膜片记录，CPA激活一个持续的内向电流在负膜电位，这持续在透析与BAPTA的细胞，表现出近线性依赖于膜电位时，Cs+是主要的细胞内阳离子，并阻止Ni 2+，Cd 2+，和SKF 96365的浓度防止收缩。该电流对细胞外Ca ~（2+）呈双峰依赖性，在无Ca ~（2+）时增强2倍，在Ca ~（2+）从1.8降至0.2 mmol/L时增强约10倍。RT-PCR显示Trp 1，Trp 3，Trp 4，Trp 5和Trp 6 mRNA的表达，而免疫组化染色鉴定Trp 1，Trp 3，Trp 4和Trp 6通道蛋白在分离的PASMCs。这些亚基中至少有一个可能对PASMCs中的阳离子通道有贡献，阳离子通道被钙池耗尽激活，引起Ca 2+内流和收缩。
Cation channels activated by Ca2+ store depletion have been proposed to mediate Ca2+ influx in vascular smooth muscle cells. The aim of this study was to determine if store-operated channels have a functional role in pulmonary artery smooth muscle cells (PASMCs). In intact rat pulmonary artery rings, cyclopiazonic acid (CPA) produced a sustained contraction that was resistant to inhibition by nifedipine, but abolished in Ca2+-free solution and 50% blocked in the presence of 6 mu mol/L Cd2+, 10 mu mol/L Ni2+, 600 mu mol/L La3+, and 7 mu mol/L SKF96365. In freshly isolated PASMCs loaded with fura-2, CPA increased the intracellular Ca2+ concentration by stimulating dihydropyridine-resistant Ca2+ influx, which was approximate to 50% blocked by 10 mu mol/L Ni2+ and 7 mu mol/L SKF96365. In perforated-patch recordings, CPA activated a sustained inward current at negative membrane potentials, which persisted in cells dialyzed with BAPTA, showed a near linear dependence on membrane potential when Cs+ was the main intracellular cation, and was blocked by Ni2+, Cd2+, and SKF96365 at concentrations preventing contraction. The current showed a bimodal dependence on extracellular Ca2+, being enhanced 2-fold in the absence of Ca2+ and around 10-fold on reducing Ca from 1.8 to 0.2 mmol/L. RT-PCR revealed the expression of Trp1, Trp3, Trp4, Trp5, and Trp6 mRNA, whereas immunostaining identified Trp1, Trp3, Trp4, and Trp6 channel proteins in isolated PASMCs. At least one of these subunits may contribute to cation channels in PASMCs, which are activated by store depletion to bring about Ca2+ influx and contraction.