Analysis on local blood flow, metabolic NADH distribution and micro-mechanical dysfunction during ischaemia of coronary micro-circulation

我们通过直接评价冠状动脉微循环NADH荧光图像和分子血流示踪剂测量毛细血管血流分布，分析心肌微循环缺血和线粒体功能障碍的空间异质性。NADH荧光成像系统有一个40万像素的CCD相机，用于观察发射荧光（420 - 570 nm）对激发紫外线的影响。该系统具有易于荧光观测NADH动力学和高空间分辨率和高时间分辨率的优点。血流分布成像采用分子血流示踪剂（3h -去甲基咪帕明），空间分辨率为100mm。实验采用离体大鼠心脏60秒低氧灌注制备。实验期间，记录心脏NADH荧光，并给予分子血流示踪剂。本研究的结果是：缺氧灌注后，NADH强度与线粒体内NADH数量成比例增加，出现高、低NADH强度混合的斑片状模式（大小为几百微米）。分子示踪剂同时测量的血流分布也显示出空间的不均匀性，每个斑点区域的大小都在几百微米左右，这与NADH荧光观察到的斑块区域几乎一致。此外，在100微米大小的心肌微循环水平上测量的微应变在心脏表面也表现出异质性。综上所述，血流量、代谢功能障碍和微应变之间存在分布关系。提示异质心肌缺血面积与血液分布和线粒体代谢功能障碍密切相关。

We analyzed ischaemia of myocardial micro-circulation and spatial heterogeneity of mitochondrial dysfunction by direct evaluation of NADH fluorescent image in coronary micro-circulation and measurement of capillary blood flow distribution using molecular blood flow tracer. NADH fluorescence imaging system has a CCD camera with 400 thousand pixels to observe the emission fluorescence (420 - 570 nm) against ex-citation ultraviolet ray. The advantages of this system are easy observation by fluorescence for NADH dynamics and high spatial resolution with high time resolution. Blood flow distribution imaging was achieved with molecular blood flow tracer (3H-Desmethylimipramine) with 100 mm spatial resolution. Experiment was performed by 60 seconds hypoxic perfusion in isolated rat heart perfusion preparation. During the experiment, NADH fluorescence from the heart was recorded and molecular blood flow tracers were administered. The findings of the present study were; NADH intensity increased in proportion to the intra-mitochondrial NADH amount immediately after hypoxic perfusion and patchy patterns appeared with mixture of high and low intensity of NADH (several hundreds microns in size). Simultaneous measurement of blood flow distribution by molecular tracers also showed spatial heterogeneity and the size of each spotty area was in order of several hundred microns, which was almost identical with the patch area observed by NADH fluorescence. Furthermore, micro-strain measured at the level of myocardial micro-circulation with the size of a hundred microns also showed heterogeneity on the surface of a heart. Taken together, there is a relationship in distribution among blood flow, metabolic dysfunction and micro-strain. This indicates that hetrogenous myocardial ischaemic area is closely related with blood distribution and mitochondrial metabolic dysfunction.