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

[目的]观察心肌细胞表面NADH荧光的变化，探讨一氧化氮(NO)在缺血心肌能量代谢中的作用，以探讨增龄和高血压对心肌能量代谢的影响。[方法]大鼠离体心(WKY为9周，16周；SHR为9周，16周)，用朗宁多夫灌流，低灌流后再灌流。实时录像NADH图像，测量冠脉流出液中NOx浓度的时程变化。[结果]在所有离体心中，低灌注期NADH荧光呈不均一性增强，而后趋于稳定。在再灌流过程中，这种异质荧光模式迅速恢复到对照水平。低灌注期NADH荧光强度的最大变化以16周自发性高血压组明显大于其他组。低灌注期最大NOx产生量在WKY组接近9wk时显著增加，而其他组无明显增加。[结论]低灌流/再灌流过程中心肌能量状态变化不均匀。NO可能通过维持低灌流/再灌注期心肌能量代谢来调节低灌注期冠脉微循环的分布。NADH荧光的异质性分布和时程变化与增龄和高血压有关，可能反映了冠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.