尼莫地平和氯胺酮对缺血再灌注兔脑血流及代谢的影响

Effects of Nimodipin and Ketamine on Cerebral Blood Flow and Metabolism in Rabbits with Cerebral IschemicReperfusion

摘要:

目的：观察尼莫地平和氯胺酮对全脑缺血再灌注兔脑血流及代谢的影响。方法：制作兔全脑缺血再灌注模型 ,随机分为缺血组、尼莫地平组和氯胺酮组 ,假手术组为对照组。结果：①缺血组于再灌注2 ,6 ,2 4h内大脑中动脉平均血流速度 (Vm)分别为(14 .5 0± 3.2 5 ) ,(14 .13± 2 .96 ) ,(14 .31± 2 .96 )cm/s,明显低于缺血前[(2 3.4 4± 3.13)cm/s]及同时间点其它 3组(P <0 .0 5 ) ,其它 3组缺血或假手术前后及 3组之间大脑中动脉Vm无明显差异。②与缺血或假手术前比较 ,4组缺血再灌注后血乳酸值均明显增高 (P <0 .0 5 )。缺血组和尼莫地平组再灌注后血乳酸和动静脉氧压差 (AVDO2 )明显高于缺血前和同时间点的假手术组和氯胺酮组(P <0 .0 5 )。③尼莫地平组血压、心率在再灌注 2h ,6h明显低于缺血前及其它 3组 (P <0 .0 5 )。结论：尼莫地平和氯胺酮均可增加脑血流 ,氯胺酮同时可减低血乳酸和AVDO2 ,提示小剂量氯胺酮有一定脑保护作用。该实验尼莫地平未能改善脑代谢及预后 ,可能与其心血管抑制副作用有关。

Abstract:

OBJECTIVE: To study the effects of nimodipin and ketamine on cerebral blood flow and metabolism in rabbits with global ischemic reperfusion. METHODS: The model of global cerebral ischemic reperfusion was established in rabbits. The ischemic rabbits were randomly assigned into an ischemic group, a nimodipin treatment group and a ketamine treatment group (n=8 each). Eight sham operated rabbits were served as the non ischemic controls. RESULTS: ①The mean flow velocities (Vm) [( 14.50 ± 3.25 ), ( 14.13 ± 2.96 ) and ( 14.31 ± 2.96 ) cm/s] of right middle cerebral artery (MCA) in the ischemic group at 2 h, 6 h and 24 h of reperfusion were significantly decreased compared with that of pre ischemia [( 23.44 ± 3.13 ) cm/s] and those of the control group, nimodipin treatment group and ketamine treatment group (P< 0.05 ). There was no significant difference in the Vm between before and after operation in the control group, nimodipin treatment group and ketamine treatment group; no significant difference was noted among the three groups. ②Compared with the indexes before operation, the plasma lactic acids in all four groups at 2 h, 6 h and 24 h after ischemic reperfusion were significantly increased (P< 0.05 ). The plasma lactic acid level and arteriovenous oxygen differences (AVDO 2) were higher in both the ischemic and nimodipin treatment groups than those in the non ischemic control and ketamine treatment groups after reperfusion (P< 0.05 ). ③ The mean blood pressure and heart rate decreased in the nimodipin group at 2 h and 6 h after reperfusion compared with those of before administrating nimodipin and those of the other three groups (P< 0.05 ). CONCLUSIONS: Both nimodipin and ketamine could improve cerebral blood flow velocity of rabbits. Ketamine could decrease plasma lactic acid level and AVDO 2, indicating ketamine may have protective effects on brain of rabbits with ischemic reperfusion. Nimodipin failed to improve the cerebral metabolism might be the consquence of its effects of restraining the function of cardiovascular system.