Somerson S K, Stokes B T
Exp Neurol. 1987 Apr;96(1):82-96. doi: 10.1016/0014-4886(87)90170-1.
Feedback control in our injury device allowed the impactor to be sensitive to the biomechanical characteristics of the spinal cord and produce mechanically predictable injuries. We tested the hypotheses that (i) extracellular calcium [( Ca2+]e) in the rat spinal cord recovers with a time course dependent on the magnitude of injury intensity, (ii) [Ca2+]e is initially depressed at the injury epicenter to the same degree independent of injury severity, and (iii) acute (less than 3.0 h) recovery of [Ca2+]e to normal values occurs in that group of animals that shows only transient neurologic deficits in the postinjury period. Three levels of injury (light, intermediate, and heavy) were produced by controlling spinal displacement during the injury process. After injury, [Ca2+]e at the injury site decreased to values less than 0.1 mM and then recovered during the next 3 h. Incomplete recoveries occurred in the intermediate- and heavy-injury groups (0.72 +/- 0.01 and 0.58 +/- 0.01 mM, respectively). [Ca2+]e activity in the lightly injured group recovered to normal values by 3 h. Specific injury protocols therefore resulted in reproducible responses in the cellular microenvironment. Behavioral recovery could be predicted from mechanical impact parameters. Animals in the light-injury group had transient neurologic deficits in some behavioral tests (open-field walking) with no alteration in others (inclined-plane analysis). Neurologic tests that required coordination between fore and hind limbs (grid walking) did not reveal significant deficiencies until 14 days postinjury. Those animals in the intermediate and heavy groups showed initial and continuing neurological effects in all behavioral measures. It is therefore probable that acute mechanical descriptors and hypocalcia transients are predictive of the ongoing and subsequent pathology of spinal cord injury.
我们的损伤装置中的反馈控制使撞击器能够对脊髓的生物力学特性敏感，并产生机械上可预测的损伤。我们测试了以下假设：（i）大鼠脊髓中的细胞外钙[Ca2+]e随时间恢复，其时间进程取决于损伤强度的大小；（ii）[Ca2+]e在损伤中心最初降低到相同程度，与损伤严重程度无关；（iii）在损伤后仅表现出短暂神经功能缺损的那组动物中，[Ca2+]e在急性（小于3.0小时）内恢复到正常值。通过在损伤过程中控制脊柱移位产生了三种损伤水平（轻度、中度和重度）。损伤后，损伤部位的[Ca2+]e降至低于0.1 mM的值，然后在接下来的3小时内恢复。中度和重度损伤组出现不完全恢复（分别为0.72±0.01和0.58±0.01 mM）。轻度损伤组的[Ca2+]e活性在3小时时恢复到正常值。因此，特定的损伤方案在细胞微环境中产生了可重复的反应。行为恢复可以从机械冲击参数中预测。轻度损伤组的动物在一些行为测试（旷场行走）中有短暂的神经功能缺损，而在其他测试（斜面分析）中没有改变。需要前肢和后肢协调的神经测试（网格行走）直到损伤后14天才显示出明显的缺陷。中度和重度组的那些动物在所有行为测量中都表现出初始和持续的神经学影响。因此，急性机械描述符和低钙血症瞬变可能预测脊髓损伤的持续和后续病理。
