IMAGING OF MYOCARDIAL METABOLISM AND CORONARY MICROCIRCULATION DURING MYOCARDIAL ISCHEMIA/REPERFUSION

[目的]通过观察心肌表面NADH荧光的变化，探讨心肌缺血时一氧化氮（NO）对心肌能量代谢的贡献以及衰老和高血压对这些参数的影响。[方法]离体大鼠心脏（WKY为9、16周，SHR为9、16周）langendorff灌注，低灌注后再灌注。实时视频记录NADH图像，并测量冠状动脉流出物中NOx浓度的随时间变化。{结果]在所有离体心脏中，低灌注时NADH荧光均呈非均匀性增加，然后达到稳定水平。这种非均匀的荧光模式在再灌注期间迅速恢复到对照水平。低灌注时NADH荧光强度的最大变化在16周SHR组明显大于其他组。低灌注时的最大NOx产量在9周左右显著增加，而其他组没有增加。[结论]低灌注/再灌注时心肌能量状态变化具有异质性。一氧化氮可能在低灌注/再灌注心肌能量代谢维持方面参与了低灌注时冠状动脉微循环分布的调节。NADH荧光的异质性分布和时间变化与衰老和高血压有关，可能反映了冠状动脉微循环和心肌氧平衡的功能和结构变化。

[Objective] To evaluate the contribution of nitric wide (NO) to myocardial energy metabolism during ischemia aid the effects of aging and hypertension on those parameters, we observed changes in myocardial surface NADH fluorescence. [Methods] Isolated rat hearts (WKY of 9, 16 wks ; SHR of 9, 16 wks) were Langendorff-perfused and were subjected to hypoperfusion followed by reperfusion. NADH images were real-timely video-recorded and time-course changes in NOx concentration in the coronary effluent was measured. {Results] In all isolated hearts, NADH fluorescence during hypoperfusion increased heterogeneously and then reached a steady level. This heterogeneous fluorescent pattern returned to the control level rapidly during reperfusion. Maximum changes of NADH fluorescent intensity during hypoperfusion were significantly greater in 16-wk SHR than that in other groups. Maximum NOx production during hypoperfusion significantly increased approximately in 9-wk WKY, while did not increase in other group. [Conclusions] Myocardial energy status changes heterogeneously during hypoperfusion/reperfusion. NO seems to be involved in regulation of the distribution of coronary microcirculation during hypoperfusion in the aspect of maintenance of the myocardial energy metabolism during hypoperfusion/reperfusion. The heterogenous distribution and time-course changes of NADH fluorescence were correlated with aging and hypertension and may reflect functional and structural changes in the coronary microcirculation and myocardial oxgen balance.