钙通道阻滞剂对缺血再灌注兔脑皮层NO和含水量及细胞内游离钙的影响

The effects of calcium channel blockers on nitric oxide, water content of cerebral cortex,and intracellular free cytoplasmic calcium after cerebral ischemia-reperfusion in rabbit

目的 探讨一氧化氮 (NO)在缺血再灌注脑损伤中的作用 ,比较两类钙通道阻滞剂的脑保护作用。方法 采用四血管夹闭法制作兔脑缺血再灌注模型。首先测定假手术及再灌注不同时间兔脑皮层NO及含水量。并将动物分为假手术组、安慰剂组、尼莫地平组、氯胺酮组、尼莫地平 +氯胺酮治疗组 ,于再灌注 30min开始持续静脉给药至再灌注 6h。测定脑皮层NO、含水量、细胞内游离钙([Ca2 + ]i)相对荧光强度。结果 再灌注后脑皮层NO、含水量逐渐升高 ,于再灌注 6h达较高水平 [分别为 (14 7± 1 7) μmol/g ,(86 7± 1 9) % ,P <0 0 5 ],NO与含水量间具有相关性 (P <0 0 1)。尼莫地平、尼莫地平 +氯胺酮组NO明显降低 [分别为 (5 1± 0 9) μmol/g、(5 1± 1 1) μmol/g ,P <0 0 1],尼莫地平、氯胺酮以及尼莫地平 +氯胺酮组含水量明显降低 [分别为 (76 3± 4 0 ) %、(81 0± 1 9) %、(78 2± 1 4 ) % ,P <0 0 1],尼莫地平组较氯胺酮组降低更明显 (P <0 0 1)。安慰剂组 [Ca2 + ]i 较假手术组明显升高 [分别为 (2 6 8± 1 4 )、(5 0± 0 4 ) ,P <0 0 1],尼莫地平、氯胺酮及尼莫地平 +氯胺酮治疗后 [Ca2 + ]i 明显降低 [分别为 (7 7± 1 1)、(13 3± 2 0 )、(9 0± 2 0 ) ,P <0 0 1]。尼莫地平组较氯胺酮?

Objective This experiment was designed to study the role of nitric oxide during cerebral ischemia reperfusion damage, to evaluate the protective effects of different calcium channel blockers, nimodiping and ketamine Methods A rabbit model of ischemia was established by transient clamping the bilateral common artery and vertebral artery for 30 min Thirty six New Zealand rabbits were randomly divided into 6 groups: control group, reperfusion 0 5 h, 1 5 h, 3 h, 6 h and 24 h groups The contents of cortex homogenates NO and water were measured Another 36 rabbits were randomly divided into five groups: control group, nimodipine group [5 μg/kg injected intravenously within 20 min as the first dosage, 0 5 μg/(kg·min) as the maintenance dosage], ketamine group [20 mg/kg injected intravenously within 30 min as the first dosage, 10 mg/(kg·h) as the maintenance dosage], nimodipine plus ketamine group and, placebo group (0 9% normal saline) All rabbits were dripped intravenously with different drugs 0 5 h after the reperfusion, and executed 6 h after the reperfusion The contents of cortex homogenates NO and water and the intracellular free cytoplasmic calcium were measured by the application of Griess method, Fluo 3 as a fluorescent calcium indicator, and the confocal laser scanning microscopy for visualizing [Ca 2+ ] i in fresh brain slice, respectively Results The contents of NO and water in cerebral cortex increased markedly 6 hours after the reperfusion [(14 7±1 7)μmol/g and (86 7±1 9)%, respectively, P <0 05] There was a correlation between the content of NO and water ( r =0 577, P <0 01) The content of NO decreased significantly in the nimodipine group and nimodipine plus ketamine group [(5 1±0 9) and(5 1±1 1)μumol/g,respectively, P <0 01] The water content of cerebral cortex declined dramatically in the nimodipine, ketamine, and nimodipine plus ketamine groups [(76 3±4 0),(81 0±1 9) and (78 2±1 4)%, respectively, P <0 01 ] The effect was more obvious in the nimodiping group than the ketamine group Compared to the control group, [Ca 2+ ] i in the placebo group dramatically increased after the ischemia reperfusion [(5 0±0 4) and (26 8±1 4), P <0 01] The levels of [Ca 2+ ] i declined dramatically in the nimodipine, ketamine and nimodipine plus ketamine groups [(7 7±1 1),(13 3±2 0) and(9 0±2 0), P <0 01], among which the decrease was much obvious in the nimodipine group than in the ketamine group ( P <0 01) Conclusion NO showed a closer relationship with the ischemia reperfusion injuries Both nimodipine and ketamine have the protective effect to the ischemia cortex Nimodipine seemed to play a significant role of protection than ketamine