氨基酸在长时间心脏停搏中对心肌的保护作用

Myocardial Protective Effect of Amino Acids in Prolonged Cardioplegia

目的：探讨谷氨酸盐（Ｇ）和天门冬氨酸盐（Ａ）在长时间心脏缺血的心肌保护作用。方法：离体大鼠工作心模型。心脏在１５°Ｃ缺血１５０分钟。４８只Ｗｉｓｔａｒ大鼠分为３组：１组，即对照组（ｎ＝１６），心脏用多剂量４°ＣＳｔ．Ｔｈｏｍａｓ冷晶体心脏停搏液结合温血停搏液诱导及终末再灌注进行心肌保护；２组（ｎ＝１６）同１组，但温血停搏液含Ｇ和Ａ各１３ｍｍｏｌ／Ｌ；３组（ｎ＝１６）同１组，但Ｓｔ．Ｔｈｏｍａｓ冷晶体心脏停搏液和温血停搏液中均含相同浓度的Ｇ和Ａ。结果：温血停搏液中应用Ｇ和Ａ能增加心肌的收缩性和心输出量，使缺血后心肌耗氧量恢复较好（Ｐ＜０．０５）。Ｓｔ．Ｔｈｏｍａｓ冷晶体心脏停搏液和温血停搏液中应用Ｇ和Ａ均明显增加心肌保护，使心功能和心肌耗氧量几乎完全恢复。缺血后心肌酶漏出少，缺血前后心肌高能磷酸盐含量和含水量无明显变化，超微结构改变也不明显。结论：含Ｇ和Ａ温血停搏液诱导及终末再灌注增加冷晶体心脏停搏液对长时间心脏停搏的心肌保护效果。

Objective:To investigate the effects of glutamate and aspartate(G and A) on prolonged heart ischemia. Methods:Hearts were exposed to global ischemia at 15°C for 150 minutes with an isolated working rat heart model.48 male Wistar rats were randomly divided into 3 groups:Group 1( n =16),control,received multidose of 4°C St.Thomas solution(STS) with warm blood cardioplegia induction and terminal reperfusion.Group 2( n =16),the same as group 1,but received blood cardioplegia enriched with 13mmol/L of G and A each.Group 3( n =16),similar to group 1,but 13mmol/L of G and A each was added in STS and induction and terminal blood cardioplegia. Results:The group 2 showed greater recovery of +dp/dt max ,cardiac output(CO),myocardial oxygen uptake(MVO 2) than group 1( p <0.05).Group 3 had the greatest recovery.After ischemia,the contents of myocardial adenosine triphosphate(ATP)and water had no marked change and myocardial ultrastructure had no apparent damage either;the release of myocardial enzyme such as lactate dehydragenase(LDH)was less. Conclusion:The warm blood cardioplegia induction and terminal reperfusion enriched with G and A increase the effect of myocardial protection in prolonged STS cardioplegia.The G and A added also in STS enhance tolerance of prolonged myocardial ischemia.