INVESTIGATION OF MECHANISM AT REPERFUSION INJURY AFTER ACUTE MYOCARDIAL INFARCTION

再灌注损伤可能是急性心肌梗死的重要并发症和不良预后。在冠状动脉循环中，NO的耗竭和过量被认为在冠心病和心脏病中起着至关重要的作用。本研究的目的是研制一种用于冠状静脉窦的导管型NO传感器，并评价其在体内的适用性，以及这种导管型NO传感器是否可用于再灌注损伤的研究。在麻醉犬右颈静脉经7-Fr Jr导管在冠状静脉置入软尖4-Fr导管内的NO传感器(创新仪器)以保护血管壁。同时测量冠状动脉左前降支血流速度。左冠状动脉分别注入乙酰胆碱(ACh，0.4和1.0ming/kg)和N-甲基-L-精氨酸(L，10μ/kg/min，20min)刺激和抑制NO的产生。ACh可剂量依赖性地升高冠状静脉窦血浆NO浓度(分别为6.8±2.1 nM和8.2±2.5 nM，p=0.05)。冠脉内注射ACh后，L-NAME降低基础NO浓度(3.1±0.8nM)，抑制NO合成(P=0.0 3和2.8±0.8nM，P=0.0 5)。注射ACh后，NO浓度达到峰值的时间明显长于冠脉血流速度(118±48秒和52±21秒，P=0.04)。总之，新开发的导管式NO传感器可以实时评估冠状静脉窦内NO浓度的变化。这种NO传感器将有助于了解NO在健康和疾病中调节冠状动脉血流和心功能中的作用，诊断冠状动脉内皮功能障碍，并导致再灌注损伤的研究。

Reperfusion injury should be important complication and poor prognosis of acute myocardial infarction. In the coronary circulation, depletion and excessiveness of NO have been considered to play crucial roles in coronary and cardiac diseases. The aim of this study was to develop a catheter-type NO sensor for the coronary sinus and evaluate its applicability in vivo, and whether this catheter-type NO sensor would be useful in the investigation of reperfusion injury. An NO sensor(Innovative Instruments) mounted in 4-Fr catheter with soft tip for protection of vascular wall was placed in the coronary sinus through a 7-Fr JR catheter from the right jugular vein of anesthetized dogs. Coronary flow velocity was measured by a Doppler flowire(Volcano) in the left anterior descending artery, simultaneously. Acetylcholine (ACh,0.4 and 1.0μg/kg) and N^G-methyl-L-arginine(L-NAME,10μg/kg/min for 20min) were infused into the left coronary artery to stimulate and inhibit NO production, respectively. ACh increased the plasma NO concentration in the coronary sinus in a dose-dependent manner(6.8±2.1nM and 8.2±2.5nM, respectively, p=0.05). L-NAME decreased basal NO concentration(3.1±0.8nM) and suppressed the NO synthesis in response to ACh intracoronary injection(1.9±0.6nM, p=0.03 and 2.8±0.8nM, p=0.05 before L-NAME, respectively). The time for base-to-peak change in NO concentration was longer than that in coronary flow velocity after ACh injection(118±48 sec and 52±21,p=0.04). In conclusion, the newly developed catheter-type NO sensor can assess the real-time changes of NO concentration in the coronary sinus. This NO sensor will contribute to understanding the roles of NO in regulations of coronary blood flow and cardiac function in health and disease, diagnosing coronary endothelial dysfunction and lead to the investigation of reperfusion injury.