Leybaert L, de Hemptinne A
Laboratorium voor Normale en Pathologische Fysiologie, Universiteit Gent, Belgium.
Exp Brain Res. 1996 Dec;112(3):392-402. doi: 10.1007/BF00227945.
Intracellular calcium ions are, in addition to free radicals, an important mediator of tissue destruction following traumatic injury to the spinal cord. In vivo measurements of calcium in the interstitial space and in the tissue suggest the occurrence of a posttraumatic shift of calcium from the extracellular to the intracellular compartment at the injury site. No information is, however, available on the posttraumatic changes of calcium in the intracellular compartment, where the ion exerts its crucial messenger function. We developed an in vitro model of local traumatic spinal injury, using a spinal cord slice preparation, allowing us to investigate injury-related changes of intracellular free calcium. The injury consisted of the impact of a small needle, and intracellular free calcium was measured with fura-2. Application of the injury at different places within the gray matter caused a transient and reproducible increase in the fura-2 fluorescence ratio. This injury-induced ratio increase was largely, but not completely, suppressed under zero extracellular calcium conditions. It was also largely depressed in the presence of high extracellular potassium and in the absence of extracellular sodium. It was modestly depressed by the calcium channel blocker nifedipin, by the calcium release channel blocker dantrolene, and by the gap junction blockers halothane and octanol. The calcium channel blocker flunarizine, the N-methyl D-aspartate (NMDA)-receptor-channel blocker MK-801 and the endoplasmic reticulum calcium-ATPase blocker thapsigargin had no effect. The experiments suggest that injury is associated with an increase in intracellular free calcium that is mediated by calcium influx, in part via L-type calcium channels. They furthermore give evidence that sodium influx and gap junctions are involved in these injury-associated changes of intracellular free calcium.
除自由基外，细胞内钙离子是脊髓创伤性损伤后组织破坏的重要介质。对间质空间和组织中钙的体内测量表明，损伤部位存在创伤后钙从细胞外隔室向细胞内隔室的转移。然而，关于细胞内隔室中钙的创伤后变化尚无信息，而钙离子在该隔室中发挥其关键的信使功能。我们使用脊髓切片制备技术建立了局部创伤性脊髓损伤的体外模型，使我们能够研究与损伤相关的细胞内游离钙的变化。损伤由小针撞击造成，并用fura-2测量细胞内游离钙。在灰质内不同位置施加损伤会导致fura-2荧光比值出现短暂且可重复的增加。这种损伤诱导的比值增加在细胞外钙为零的条件下大部分但并非完全受到抑制。在细胞外钾浓度高且无细胞外钠的情况下，它也大幅降低。钙通道阻滞剂硝苯地平、钙释放通道阻滞剂丹曲林以及缝隙连接阻滞剂氟烷和辛醇可使其适度降低。钙通道阻滞剂氟桂利嗪、N-甲基-D-天冬氨酸（NMDA）受体通道阻滞剂MK-801和内质网钙ATP酶阻滞剂毒胡萝卜素则无作用。实验表明，损伤与细胞内游离钙增加有关，这种增加部分通过L型钙通道由钙内流介导。此外，实验还证明钠内流和缝隙连接参与了这些与损伤相关的细胞内游离钙变化。
