Properties of a native cation channel activated by Ca2+ store depletion in vascular smooth muscle cells
Properties of a native cation channel activated by Ca2+ store depletion in vascular smooth muscle cells
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DOI：
10.1074/jbc.m010104200
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发表时间：
2001-03-16
影响因子：
4.8
通讯作者：
Bolotina, VM
中科院分区：
文献类型：
--
作者：
Trepakova, ES;Gericke, M;Bolotina, VM
细胞内钙库的耗竭激活平滑肌细胞中的容量性钙内流，但介导这种内流的天然钙库操纵通道仍未确定。最近，我们表明，钙内流因子产生的酵母和人血小板与耗尽的Ca 2+商店激活小电导阳离子通道从血管平滑肌细胞（SMC）的离体膜补丁。在这里，我们的特点，这些渠道在完整的细胞和目前的证据表明，他们属于一类的商店经营的渠道，这是激活后，被动耗尽的Ca 2+商店。应用毒胡萝卜素（TG），肌内质网钙ATP酶的抑制剂，个别SMC激活单个3-pS阳离子通道的细胞贴附膜补丁。当从细胞中切除由内而外的膜补丁时，通道仍然活跃。从静息SMC上切除膜斑本身并不能激活通道。用BAPTA负载SMC（1，2-双（2-氨基苯氧基）乙烷-N，N，N '，N'-四乙酸）缓慢消耗钙库而不增加细胞内钙，激活细胞贴附膜中相同的3-pS通道以及SMC中的全细胞非选择性阳离子电流，TG-和BAPTA-激活的3-pS通道具有阳离子选择性，但在Ca 2+，Sr 2+，Ba 2+，Na+、K+和Cs+。开放通道的概率没有改变，在负的膜电位，但在高的正电位显着增加。3-pS通道的激活不依赖于细胞内Ca ~（2+）浓度。TG和各种第二信使（包括Ca 2+、InsP 3、InsP 4、GTP γ S、cAMP、cAMP、ATP和ADP）均未激活由内而外的膜斑中的3-pS通道。因此，3-pS非选择性阳离子通道的存在和激活的TG或BAPTA诱导的细胞内钙库的消耗在完整的SMC。这些天然的钙池操纵的阳离子通道可以解释SMC中的容量性Ca 2+内流，并且可以在调节血管张力中发挥重要作用。
Depletion of intracellular Ca2+ stores activates capacitative Ca2+ influx in smooth muscle cells, but the native store-operated channels that mediate such influx remain unidentified. Recently we demonstrated that calcium influx factor produced by yeast and human platelets with depleted Ca2+ stores activates small conductance cation channels in excised membrane patches from vascular smooth muscle cells (SMC). Here we characterize these channels in intact cells and present evidence that they belong to the class of store-operated channels, which are activated upon passive depletion of Ca2+ stores. Application of thapsigargin (TG), an inhibitor of sarco-endoplasmic reticulum Ca2+ ATPase, to individual SMC activated single 3-pS cation channels in cell-attached membrane patches. Channels remained active when inside-out membrane patches were excised from the cells. Excision of membrane patches from resting SMC did not by itself activate the channels. Load-ing SMC with BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid), which slowly depletes Ca2+ stores without a rise in intracellular Ca2+, activated the same 3-pS channels in cell-attached membrane patches as well as whole cell nonselective cation currents in SMC, TG- and BAPTA-activated 3-pS channels were cation-selective but poorly discriminated among Ca2+, Sr2+, Ba2+, Na+, K+, and Cs+. Open channel probability did not change at negative membrane potentials but increased significantly at high positive potentials. Activation of 3-pS channels did not depend on intracellular Ca2+ concentration. Neither TG nor a variety of second messengers (including Ca2+, InsP3, InsP4, GTP gammaS, cyclic AMP, cyclic GIMP, ATP, and ADP) activated 3-pS channels in inside-out membrane patches. Thus, 3-pS nonselective cation channels are present and activated by TG or BAPTA-induced depletion of intracellular Ca2+ stores in intact SMC. These native store-operated cation channels can account for capacitative Ca2+ influx in SMC and can play an important role in regulation of vascular tone.