Ca2+ paradox injury mediated through TRPC channels in mouse ventricular myocytes
Ca2+ paradox injury mediated through TRPC channels in mouse ventricular myocytes
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DOI：
10.1111/j.1476-5381.2010.00986.x
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发表时间：
2010-12-01
影响因子：
7.3
通讯作者：
Nosaka, Shuichi
中科院分区：
文献类型：
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作者：
Kojima, Akiko;Kitagawa, Hirotoshi;Nosaka, Shuichi
背景与结论心肌细胞内钙离子矛盾现象是与钙超载介导的心肌细胞损伤相关的重要现象。本研究旨在阐明钙反常现象发生的分子和细胞机制。实验方法用共聚焦激光扫描显微镜对荧光素-3负载的静止小鼠心室肌细胞进行荧光成像。关键词钙反常现象很容易通过10-20分钟名义上无钙灌流后细胞外钙的恢复引起。瞬时受体电位经典（TRPC）通道阻断剂（2-氨基乙氧基二苯基硼酸盐，Gd 3+，La 3+）和抗TRPC 1抗体显着减少钙悖论。肌浆网（SR）的Ca 2+含量，咖啡因的应用评估，逐渐下降，在无钙灌注，这是进一步加速代谢抑制。用丁卡因阻断肌浆网Ca ~（2+）漏出，可防止Ca ~（2+）反常现象的发生。Na+/Ca 2+交换（NCX）阻断剂KB-R7943在整个灌流期间显著抑制Ca 2+悖论，但在Ca 2+恢复前和恢复期间加入3 min时效果甚微。SR Ca 2+含量在KB-R7943的Ca 2+耗竭期间得到更好的保持。免疫细胞化学证实了TRPC 1的表达，除了TRPC 3和TRPC 4，在小鼠心室肌细胞。结论和意义这些结果提供证据表明：（i）钙悖论主要是由钙离子通过TRPC内流介导的（可能是TRPC 1）通道，推测由SR Ca 2+耗尽激活;（ii）反向模式NCX对Ca ~（2+）悖论的贡献很小，而在Ca ~（2+）耗竭期间抑制NCX可改善SR Ca ~（2+）负荷，并与小鼠心室肌细胞Ca ~（2+）悖论的发生率降低有关。
BACKGROUND AND PURPOSEThe Ca2+ paradox is an important phenomenon associated with Ca2+ overload-mediated cellular injury in myocardium. The present study was undertaken to elucidate molecular and cellular mechanisms for the development of the Ca2+ paradox.EXPERIMENTAL APPROACHFluorescence imaging was performed on fluo-3 loaded quiescent mouse ventricular myocytes using confocal laser scanning microscope.KEY RESULTSThe Ca2+ paradox was readily evoked by restoration of the extracellular Ca2+ following 10-20 min of nominally Ca2+-free superfusion. The Ca2+ paradox was significantly reduced by blockers of transient receptor potential canonical (TRPC) channels (2-aminoethoxydiphenyl borate, Gd3+, La3+) and anti-TRPC1 antibody. The sarcoplasmic reticulum (SR) Ca2+ content, assessed by caffeine application, gradually declined during Ca2+-free superfusion, which was further accelerated by metabolic inhibition. Block of SR Ca2+ leak by tetracaine prevented Ca2+ paradox. The Na+/Ca2+ exchange (NCX) blocker KB-R7943 significantly inhibited Ca2+ paradox when applied throughout superfusion period, but had little effect when added for a period of 3 min before and during Ca2+ restoration. The SR Ca2+ content was better preserved during Ca2+ depletion by KB-R7943. Immunocytochemistry confirmed the expression of TRPC1, in addition to TRPC3 and TRPC4, in mouse ventricular myocytes.CONCLUSIONS AND IMPLICATIONSThese results provide evidence that (i) the Ca2+ paradox is primarily mediated by Ca2+ entry through TRPC (probably TRPC1) channels that are presumably activated by SR Ca2+ depletion; and (ii) reverse mode NCX contributes little to the Ca2+ paradox, whereas inhibition of NCX during Ca2+ depletion improves SR Ca2+ loading, and is associated with reduced incidence of Ca2+ paradox in mouse ventricular myocytes.