左旋精氨酸对犬深低温停循环脑组织代谢的影响

L-arginine pretreatment lowers cerebral metabolism for cerebral protection during deep hypothermic circulatory arrest

目的利用犬深低温停循环(DHCA)动物模型,观察左旋精氨酸(L-arg)预处理对深低温停循环中犬脑组织代谢的影响。方法健康成年杂种犬15只,随机分为3组(n=5)。对照组:生理盐水假处理;L-arg预处理组:停循环前60min给予L-arg100mg/kg预处理;联合处理组:停循环前60min给予L-arg100mg/kg、7-Ni25mg/kg联合处理。按临床方法建立体外循环转流降温至鼻咽部温18℃停循环,90min后恢复循环复温。分别于停循环前30min、停循环时(0min)、停循环45min、停循环90min、复温再灌注60min抽取颈静脉、颈动脉血测乳酸含量,取脑顶叶皮质测ATP酶活性。实验犬处死后立刻取脑测干湿重。结果L-arg预处理和联合处理脑乳酸净生成及ATP消耗均小于对照组(P<0.05),二处理组间差异无统计学意义(P>0.05)。联合处理组DHCA后脑组织含水量最低,L-arg处理次之,对照组最高,差异有统计学意义(P<0.05)。结论DHCA前给予L-arg预处理能降低脑组织代谢水平,有助于脑保护。

Objective To evaluate the effect of L-arginine pretreatment on cerebral metabolism for cerebral protection during deep hypothermic circulatory arrest （DHCA）. Methods Fifteen healthy adult canines of either sex weighing 14.7±2.4 kg were randomly divided into 3 groups （n=5）, namely the normal saline group, L-arginine pretreatment group （pretreated with 100 mg/kg L-arginine 60 min before DHCA）, and L-arginine combined with 7- nitroindazole treatment group （pretreated with 100 mg/kg L-arginine and 25 mg/kg7-Ni 60 min before DHCA）. For all the canines, extracorporeal circulation was established routinely to allow nasopharyngeal temperature reduction to 18 ℃, at which point DHCA commenced followed 90 min later by reperfusion. At 30 min before DHCA and 0, 45 and 90 min after DHCA as well as at 60 min after reperfusion initiation, blood samples were collected from the jugular vein and arterial to measure the plasma lactic acid, and the cerebral cortex of the parietal lobe was sampled determine the activity of Na^＋-K^＋ATPase. The cerebral water content was also determined after execution of the canines. Results In the two pretreatment groups, the level of lactic acid production （shown by the difference in lactic acid levels between the jugular venous and arterial blood） and the cerebral ATP consumption were similar （P〉0.05）, but both were significantly lower than those of the control group （P〈0.05）. The cerebral water content was the lowest in the combined treatment group, followed by exclusive L-arginine group, and the highest in the control group （P〈0.05）, with significant difference between the 3 groups （P〈0.05）. Conclusion L-arginine pretreatment can lower cerebral metabolism during DHCA to offer protective effect on the brain.