Orlov Sergei N, Aksentsev Sergei L, Kotelevtsev Sergei V
Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia.
Cell Calcium. 2005 Jul;38(1):53-7. doi: 10.1016/j.ceca.2005.03.006.
In contrast to rat and human erythrocytes, nucleated erythrocytes from two fish species (Cyprinus carpio and Salmo trutta) underwent almost complete haemolysis in 20 min of EDTA addition. Using Ca2+/Mg2+ EGTA-citrate buffer, we observed that half-maximal haemolysis of fish erythrocytes occurs at [Ca2+]o approximately 10 microM independently of extracellular Mg2+ concentration. Attenuation of [Ca2+]o with EGTA also decreased stability of the plasma membrane of vascular smooth muscle cells (VSMC) and HeLa cells, indicated by a three- to five-fold elevation of lactate dehydrogenase release and passive permeability of plasma membrane for Na+. In VSMC, EGTA lowered [Ca2+]i by approximately 20%. This effect was absent in VSMC-loaded with the intracellular Ca2+ chelator BAPTA. In contrast to EGTA, BAPTA did not affect haemoglobin release from fish erythrocytes and passive permeability for Na+ in VSMC. Viewed collectively, our data show that in nucleated cells, extracellular Ca2+ plays a crucial role in the maintenance of plasma membrane integrity.
与大鼠和人类红细胞不同，来自两种鱼类（鲤鱼和褐鳟）的有核红细胞在添加乙二胺四乙酸（EDTA）20分钟后几乎完全溶血。使用钙离子/镁离子-乙二醇双四乙酸-柠檬酸盐缓冲液，我们观察到鱼类红细胞半数最大溶血发生时的细胞外钙离子浓度约为10微摩尔，且与细胞外镁离子浓度无关。用乙二醇双四乙酸（EGTA）降低细胞外钙离子浓度也会降低血管平滑肌细胞（VSMC）和人宫颈癌细胞（HeLa细胞）质膜的稳定性，这表现为乳酸脱氢酶释放增加三到五倍以及质膜对钠离子的被动通透性增加。在血管平滑肌细胞中，EGTA使细胞内钙离子浓度降低约20%。在加载了细胞内钙离子螯合剂1,2-双（2-氨基苯氧基）乙烷-N,N,N',N'-四乙酸（BAPTA）的血管平滑肌细胞中不存在这种效应。与EGTA不同，BAPTA不影响鱼类红细胞中血红蛋白的释放以及血管平滑肌细胞质膜对钠离子的被动通透性。总体来看，我们的数据表明，在有核细胞中细胞外钙离子在维持质膜完整性方面起着关键作用。
