深低温停循环中不同脑灌注方式皮层超氧化物歧化酶、丙二醛及超微结构的变化

Cerebral protective effects of retrograde cerebral perfusion and selective antegrade cerebral perfusion during deep hypothermic circulatory arrest

目的观察不同脑灌注方法对深低温停循环(DHCA)中脑皮质超氧化物歧化酶(SOD)、丙二醛(MDA)及超微结构的影响,比较不同灌注方式的脑保护效果。方法健康成年杂种犬15条,随机分为3组。I组单纯行DHCA为对照,Ⅱ组DHCA+逆行脑灌注(RCP),Ⅲ组DHCA+选择性顺行脑灌注脑保护(SACP)。转流降温至鼻咽部温18℃时停循环90 min,然后复温再灌注90 min。结果停循环期皮层SOD活性下降而MDA含量上升,复温再灌注时变化更明显,各时间点差异有统计学意义(P7＜0．05)。增加或下降程度以I组最为明显,Ⅱ组次之,Ⅲ组最小。Ⅱ、Ⅲ组与I组比较SOD、MDA变化明显减轻(P＜0．01),Ⅱ、Ⅲ组间亦差异有统计学意义(P＜0．05),与电镜观察结果一致。结论深低温停循环期间SACP有明显脑保护作用,RCP亦可减轻DHCA中脑损害。

Objective To compare the cerebral protective effects between retrograde cerebral perfusion （RCP） and selective antegrade cerebral perfusion （SACP） during deep hypothermic circulatory arrest （DHCA） with canine models. Methods Fifteen healthy adult hybrid dogs were randomly divided into 3 groups （n = 5 in each group）： simple-DHCA （group Ⅰ）, DHCA ＋ RCP （group Ⅱ ） and DHCA ＋ SACP （group Ⅲ ）. Extrocorporeal circulation was established routinely in canines. When the nasopharyngeal temperature was reduced to 18 ℃, DHCA commenced. During DHCA, RCP and SACP were applied respectively in group Ⅱ and group Ⅲ . All models were rewarrned after 90 min and then the cerebral perfusion continued 90 min. The cerebral cortex oxygen free radical parameters such as superoxide dismutase （SOD） and malondialdehyde （MDA）, and ultrastructural changes were observed. Results SOD in brain cortex was decreased and MDA increased during DHCA, and the changes of SOD and MDA were more obvious after rewarm with the difference being significant among different time points （P 〈 0.05）. The activity of SOD was higher and the content of MDA lower in group Ⅲ and Ⅱ than in group Ⅰ . In group Ⅲ the activity of SOD was the highest but that of MDA was the lowest. The change in ultrastructure of nerve cells was concordant with that in SOD and MDA. Conclusion RCP and SACP can partly alleviate brain damage by oxygen free radical during DHCA.