L-精氨酸对乳猪深低温停循环脑代谢与结构的影响

The Effects of L-arginine on Cerebral Metabolism and Structure Under Deep Hypothermic Circulatory Arrest

目的 通过深低温停循环 ( DHCA)转流模型 ,研究左旋精氨酸 ( L- arg)在低温缺血时对脑代谢和结构的影响。 方法 采用上海种白猪 ,3～ 4周龄 ,随机均分成 4组 :L- arg组 ,左旋硝基精氨酸甲酯 ( L- NAME)组 ,L- arg+ L-NAME组和对照组 ,每组 10只。按临床方法行心肺转流术 ,于转流前、降温末、复温末和转流结束等分别测定颈内静脉一氧化氮 ( NO)、脑皮质三磷酸腺苷 ( ATP)和颈内静脉乳酸含量。并行脑组织学和超微结构观察。 结果 降温末 L-NAME组和对照组 NO含量较其它两组明显下降 ( P<0 .0 1)。复温末 ,除 L- NAME组外 ,其余 3组均恢复至转流前水平( P<0 .0 1) ,L- arg组 NO水平在复温末较转流前高 ( P<0 .0 1)。转流开始后大脑皮质 ATP即有明显下降 ,L- arg组下降幅度最小 ,且在复温末已接近转流前水平 ;L- NAME组下降幅度最大 ( P<0 .0 1)。转流开始后颈内静脉乳酸含量即升高 ,L- arg组和 L- arg+ L- NAME组上升幅度较小 ;降温末和转流结束乳酸含量较其它两组低 ( P<0 .0 1)。大脑皮质组织学和超微结构检查显示 ,大脑皮质细胞结构变化 L- arg组和 L- arg+ L- NAME组较对照组和L- NAME组轻。 结论 深低温停循环手术时 ,应用 L- arg具有较好的脑保护作用 ,而 L- NAME有脑损害作用。 L-

Objective With piglet deep hypothermic circulatory arrest perfusate model , the influences of L arginine (L arg) on cerebral metabolism and structure were studied. Methods Forty piglets(3 4 weeks old) were randomly divided into 4 groups: L arg group, L nitro arginine methyl ester (L NAME) group, L arg+ L NAME group and control group. Each group contained 10 piglets. After the cardiopulmonary bypass (CPB) was established through median sternotomy according to clinical method,intrajugular vein nitric oxide (NO) content, cortex adenosine triphosphate (ATP) and intrajugular vein lactate contents were measured before institusion of CPB, end of cooling, end of rewarming, and the cessation of CPB. The cortex physiology sample were also measured before and after the study. Results At the end of cooling intrajugular vein NO content was lower in L NAME group and control group than in L arg group and L arg+L NAME group ( P <0.01). At the end of rewarming all groups reached to baseline but L NAME group ( P <0.01). During normothermic bypass, L arg group produced much NO than pre CPB status ( P <0.01). After cooling the cortex ATP content decreased significantly, but L arg group had relatively higher ATP content among 4 groups, and at end of rewarming, the ATP content got near to baseline, while on the contrary, L NAME group had the lowest ATP content during cooling and rewarming ( P <0.01). After CPB the lactate content in intrajugular vein gradually increased, but in L arg group and L arg+ L NAME group the lactate content was lower than in L NAME group and control group ( P <0.01), after rewarming L arg group had a trend of declining in intrajugular vein lactate content. Histological and ultrastructure test discovered that significant denaturation of chromosome and mitochondria in L NAME group and control group rather than in L arg group and L arg+ L NAME group. Conclusion In a piglet model of deep hypothermic circulatory arrest L arg has the beneficial effects on cerebral protection and L NAME has the deleterious effects on cerebral protection. The deleterious effects of L NAME on brain are only partially reversed by L arg.