microdialysis approach to quantitative assessment of myocardial ischemic and reperfusion injuries

最近，我们发展了心脏微透析，用于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，我们研究了异氟醚的暴露是否会对缺血或再灌流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钠麻醉的兔左室游离壁。透析液肌红蛋白水平可作为心肌间质肌红蛋白水平的指标。将兔随机分为3组：(1)溶剂组(n=6)，不吸入异氟醚(n=6)。(2)吸入1MAC异氟醚1次，每次30min(ISO30-1，n=6)；(3)吸入两次，每次30min(ISO30-2，n=6)，间隔15min。异氟醚暴露后，在缺血前进行15min的洗脱，然后所有兔接受30min的冠脉阻断和60min的再灌流。结果：三组患者的透析液肌红蛋白水平均在冠脉闭塞后升高，再灌流后进一步升高。与赋形剂组相比，ISO30-1组仅抑制再灌流期间透析液中肌红蛋白水平的增加。ISO30-2组抑制了缺血和再灌注期透析液中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，但不影响缺血期的肌红蛋白释放。另一方面，异氟醚的双重暴露抑制了由缺血和再灌注损伤引起的心肌肌红蛋白的释放。与单次暴露相比，重复暴露于异氟醚可对心肌缺血或再灌注损伤提供更多的保护。

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.