Hu W, Kharlamov A, Wang Y, Perez-Trepichio A D, Jones S C
Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
Brain Res. 2000 Jun 23;868(2):370-5. doi: 10.1016/s0006-8993(00)02360-x.
Changes in sodium, potassium, and water content in brain tissue are important in the progression of pathology that follows ischemic stroke. Determining these parameters regionally in rodent models of experimental ischemia has been limited because typical tissue weights of more than 35 mg are too large. Identifying ischemic tissue to direct tissue sampling towards ischemic cortex is also represents a difficult generally unresolved area. We suggest that larger differences between normal and ischemic cortex of sodium, potassium, and water content than previously observed can be obtained from directed sampling of 2-mg brain tissue in a model of focal cerebral ischemia. In five rats, the middle cerebral artery and both common carotid arteries were occluded for 4.9+/-0.13 h (mean+/-SEM). Punch-sampling of 1-mm diameter tissue cores for water content (H(2)O%) by the wet-dry method, and [Na(+)] and [K(+)] by flame photometry, was guided by the observation of a subtle change in the surface reflectivity of ischemic cortex of quickly dried, 20-microm frozen brain sections, that was confirmed by MAP2 immunohistochemistry. The ratio of the lesion areas as determined by the reflective change and MAP2 immunoreactivity was 0.96+/-0.03 (n=5). In ischemic cortex H(2)O% was 79.9%+/-0.8%, [Na(+)] was 550+/-25 mEq/kg dry-weight, and [K(+)] 94.2+/-19.2 mEq/kg dry-weight (n=5), all significantly different from the values in border zone cortex, and in cortex contralateral to ischemic cortex and border zone (for all samples n=60, mean wet weight 2.037+/-0.046 mg). Differences between ischemic and normal cortex were 5.4+/-1.1%, 317+/-21 mEq/kg dry-weight, -304+/-27 mEq/kg dry-weight (n=5) for H(2)O%, [Na(+)], and [K(+)]. These differences between ischemic and normal cortex are 1.4-2.5, 1-3.11, and 1.4-3.5 times greater, respectively, than previous results obtained using samples weighing 35 mg or more. These results extend the association of sodium and potassium with ischemic brain edema in the rodent model, and show that these classical measurements can keep pace with the regionality of histochemical and morphological methods.
脑组织中钠、钾和水含量的变化在缺血性中风后的病理进展中起着重要作用。在实验性缺血的啮齿动物模型中，局部确定这些参数一直受到限制，因为典型的组织重量超过35毫克太大了。识别缺血组织以将组织采样导向缺血皮层也是一个普遍难以解决的难题。我们认为，在局灶性脑缺血模型中，通过对2毫克脑组织进行定向采样，可以获得比以前观察到的正常皮层和缺血皮层之间更大的钠、钾和水含量差异。在5只大鼠中，大脑中动脉和双侧颈总动脉被阻断4.9±0.13小时（平均值±标准误）。通过湿干法对直径1毫米的组织芯进行含水量（H₂O%）采样，并通过火焰光度法对[Na⁺]和[K⁺]进行采样，这是通过观察快速干燥的20微米冰冻脑切片缺血皮层表面反射率的细微变化来指导的，这一点通过MAP2免疫组织化学得到了证实。由反射变化和MAP2免疫反应性确定的病变面积比为0.96±0.03（n = 5）。在缺血皮层中，H₂O%为79.9%±0.8%，[Na⁺]为550±25 mEq/kg干重，[K⁺]为94.2±19.2 mEq/kg干重（n = 5），所有这些均与边界区皮层以及缺血皮层和边界区对侧的皮层中的值有显著差异（所有样本n = 60，平均湿重2.037±0.046毫克）。缺血皮层与正常皮层之间的差异对于H₂O%、[Na⁺]和[K⁺]分别为5.4±1.1%、317±21 mEq/kg干重、-304±27 mEq/kg干重（n = 5）。缺血皮层与正常皮层之间的这些差异分别比使用重量为35毫克或更多的样本获得的先前结果大1.4 - 2.5倍、1 - 3.11倍和1.4 - 3.5倍。这些结果扩展了啮齿动物模型中钠和钾与缺血性脑水肿的关联，并表明这些经典测量可以与组织化学和形态学方法的局部性保持同步。
