Knoop Sven, de Groot Herbert, Rauen Ursula
Institut für Physiologische Chemie, Universitätsklinikum, Hufelandstr. 55, 45122 Essen, Germany.
Cryobiology. 2008 Apr;56(2):103-13. doi: 10.1016/j.cryobiol.2007.11.002. Epub 2007 Dec 4.
We have previously shown that cold-induced injury to hepatocytes and liver endothelial cells occurs predominantly via an iron-dependent pathway. However, other groups have reported evidences suggesting that Ca(2+) ions could be involved in the process of cold-induced injury of liver cells. We here assessed the relative importance and potential interaction of both pathways in cultured primary hepatocytes and cultured liver endothelial cells. The sequence cold incubation/rewarming of hepatocytes and endothelial cells led to an increase in the cytosolic calcium concentration during the early rewarming phase, but the increased cytosolic calcium concentration did not correlate with cell injury. A partial protection from cold-induced cell injury was achieved by the intracellular calcium chelators Quin-2 and BAPTA. However, additional experiments showed that the ability of these chelators to bind iron was probably responsible for a major part of this protection. Incubation in calcium-free media led to an increased cell injury and a physiological calcium concentration (2.5mM) was protective. In addition, targeting suggested downstream pathways of calcium-dependent cold-induced injury, i.e. by the addition of Ruthenium Red, an inhibitor of mitochondrial Ca(2+) uniporter, or by inhibiting Bax translocation to the mitochondria, did not provide protection from cold-induced injury in both cell types. Taken together, our data suggest that calcium increases but does not play a major role in cold-induced cell injury to hepatocytes and liver endothelial cells.
我们之前已经表明，冷诱导的肝细胞和肝内皮细胞损伤主要通过铁依赖性途径发生。然而，其他研究小组报告的证据表明，Ca(2+)离子可能参与肝细胞冷诱导损伤的过程。我们在此评估了这两种途径在原代培养肝细胞和培养的肝内皮细胞中的相对重要性和潜在相互作用。肝细胞和内皮细胞的冷孵育/复温序列导致复温早期胞质钙浓度升高，但胞质钙浓度升高与细胞损伤无关。细胞内钙螯合剂喹啉-2（Quin-2）和1,2-双（2-氨基苯氧基）乙烷-N,N,N',N'-四乙酸（BAPTA）可部分保护细胞免受冷诱导损伤。然而，进一步的实验表明，这些螯合剂结合铁的能力可能是这种保护作用的主要原因。在无钙培养基中孵育会导致细胞损伤增加，而生理钙浓度（2.5 mM）具有保护作用。此外，针对钙依赖性冷诱导损伤的推测下游途径，即通过添加线粒体Ca(2+)单向转运体抑制剂钌红，或通过抑制Bax转位至线粒体，在这两种细胞类型中均不能提供免受冷诱导损伤的保护。综上所述，我们的数据表明，钙浓度升高，但在冷诱导的肝细胞和肝内皮细胞损伤中不发挥主要作用。
