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

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[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.