DeGraba T J, Ostrow P T, Grotta J C
Department of Neurology, University of Texas Medical School, Houston 77030.
Stroke. 1993 Aug;24(8):1212-6; discussion 1216-7. doi: 10.1161/01.str.24.8.1212.
One explanation for inconclusive results with calcium channel blockers in human acute stroke trials may be incomplete information about the time course of calcium-mediated ischemic neuronal injury. This study explores the temporal relation between duration of focal ischemia and the functional activity of increased intracellular calcium as measured by calcium-calmodulin binding.
Calcium-calmodulin binding, determined by immunohistochemical assay of free calmodulin, was measured in 60 male spontaneously hypertensive rats after 2 minutes and after 1, 2, 4, and 24 hours of permanent tandem common carotid and middle cerebral artery occlusion, and after 1 and 2 hours of reversible middle cerebral artery occlusion followed by 1 and 22 hours of reperfusion, respectively. Light microscopic histological damage was measured after 1 hour of occlusion with 23 hours of reperfusion and after 24 hours of occlusion.
Significant loss of calmodulin staining in the core of the infarction was noted by 1 hour and became maximal after 4 hours of ischemia. No reversal of calmodulin staining loss was noted after reperfusion following 1 and 2 hours of ischemia. Cortical necrosis seen by light microscopy correlated well with the area of maximal calcium-calmodulin binding. The border zone area, represented by a mild loss of calmodulin staining surrounding the central core of maximal binding, gradually decreased in size and became incorporated into the central core after 4 hours of ischemia; it may represent an area of reversible ischemia.
Calcium-calmodulin binding correlates with duration of focal ischemia, and histological neuronal necrosis corresponds to the cortical areas displaying a significant loss of calmodulin staining. Inasmuch as loss of calmodulin staining represents a marker for calcium-mediated activity after ischemia, it suggests a window of opportunity within 4 hours after acute stroke for therapeutic intervention with calcium antagonists.
钙通道阻滞剂在人类急性卒中试验中结果不明确的一种解释可能是关于钙介导的缺血性神经元损伤时间进程的信息不完整。本研究探讨局灶性缺血持续时间与通过钙调蛋白结合测量的细胞内钙增加的功能活性之间的时间关系。
通过对游离钙调蛋白的免疫组织化学测定来确定钙调蛋白结合，在60只雄性自发性高血压大鼠中进行测量，分别在永久性串联颈总动脉和大脑中动脉闭塞2分钟后以及1、2、4和24小时后，以及在可逆性大脑中动脉闭塞1和2小时后再灌注1和22小时后进行测量。在闭塞1小时后再灌注23小时以及闭塞24小时后测量光镜下的组织学损伤。
在缺血1小时时梗死核心区钙调蛋白染色明显缺失，并在缺血4小时后达到最大程度。缺血1和2小时后再灌注，未观察到钙调蛋白染色缺失的逆转。光镜下所见的皮质坏死与最大钙调蛋白结合区域密切相关。以最大结合中心核心周围钙调蛋白染色轻度缺失为代表的边缘区面积逐渐减小，在缺血4小时后并入中心核心；它可能代表可逆性缺血区域。
钙调蛋白结合与局灶性缺血持续时间相关，组织学上的神经元坏死对应于显示钙调蛋白染色明显缺失的皮质区域。由于钙调蛋白染色缺失代表缺血后钙介导活性的标志物，这提示急性卒中后4小时内存在用钙拮抗剂进行治疗干预的机会窗口。
