microdialysis approach to quantitative assessment of myocardial ischemic and reperfusion injuries

近年来，我们发展了心脏微透析技术来检测受损心肌的蛋白渗漏，并监测心肌间质肌红蛋白水平作为心肌损伤的指标。使用这种方法，我们研究了异氟烷暴露是否会对缺血或再灌注引起的心肌损伤产生有益的影响。方法：将透析探头植入戊巴比妥麻醉家兔左心室游离壁。透析液肌红蛋白水平作为心肌间质肌红蛋白水平的指标。将兔随机分配到三组中的一组：（1）媒介物组（n=6）不暴露于异氟烷（媒介物，n=6）。（2）吸入1 MAC异氟醚1次，每次30 min（ISO 30 -1，n=6）;（3）吸入2次，每次30 min（ISO 30 -2，n=6），间隔15 min的洗脱期。异氟烷暴露后，缺血前15分钟的洗脱期，然后所有兔进行30分钟的冠状动脉闭塞和60分钟的再灌注。结果：在所有三组中，冠状动脉闭塞使透析液肌红蛋白水平升高，再灌注进一步增加。与载体组相比，ISO 30 -1组仅抑制再灌注期间透析液肌红蛋白水平的增加。ISO 30 -2组在缺血和再灌注期间抑制透析液肌红蛋白水平的增加。结论：单次吸入异氟醚可抑制再灌注期心肌肌红蛋白的释放，但对缺血期心肌肌红蛋白的释放无影响。另一方面，双暴露于异氟烷抑制心肌肌红蛋白释放诱发的缺血和再灌注损伤。反复暴露于异氟烷可能比单次暴露提供更多的心肌缺血或再灌注损伤保护。

Recently we have developed cardiac microdialysis for detecting of protein leakage from the injured myocardium and monitored myocardial interstitial myoglobin levels as an index of myocardial injury. Using this method, we examined whether the exposures to isoflurane would exert a beneficial effect on myocardial injury evoked by ischemia or reperfusion. Methods : A dialysis probe was implanted into the left ventricle free wall in the pentobarbital-anesthetized rabbits. The dialysate myoglobin level served as an index of myocardial interstitial myoglobin levels. Rabbits were randomly assigned to one of three groups : (1)Vehicle group (n=6) was without exposure to isoflurane (vehicle, n=6). (2)Rabbits were made to inhale 1 MAC isoflurane once for 30-min (ISO30-1, n=6) and (3)twice for 30-min (ISO30-2, n=6), with a 15-min washout period interspersed. Isoflurane exposure was followed by a 15-min washout period before ischemia, and all rabbits then underwent 30 min of coronary occlusion and 60 min of reperfusion. Results : In all three groups dialysate myoglobin levels were increased by coronary occlusion and furthermore augmented by reperfusion. In comparison with the vehicle group, the ISO30-1 group suppressed only the increase in the dialysate myoglobin level during reperfusion. The ISO30-2 group suppressed the increases in dialysate myoglobin levels during both the ischemic and reperfusion periods. Conclusion : Single exposure to isoflurane suppressed myocardial myoglobin release during the reperfusion period but not during the ischemic period. On the other hand, dual exposure to isoflurane suppressed both myocardial myoglobin release evoked by both ischemia and reperfusion injury. Repeated exposure to isoflurane exposure may provide more protection against myocardial ischemia or reperfusion injuries than single exposure.