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中的NADH荧光图像和使用分子血流示踪剂测量毛细血管血流分布来分析心肌微循环缺血和线粒体功能障碍的空间异质性。NADH荧光成像系统具有40万像素的CCD摄像机，用于观察激发紫外线下的发射荧光（420 - 570 nm）。该系统的优点是易于通过荧光观察NADH动力学和高空间分辨率与高时间分辨率。采用3H-去甲丙咪嗪（3H-Desmethylimimimpramine）分子血流示踪剂，以100mm的空间分辨率进行血流分布显像。实验采用离体大鼠心脏灌流模型，低氧60秒灌流。在实验期间，记录来自心脏的NADH荧光，并施用分子血流示踪剂。本研究的结果是：缺氧灌注后，NADH强度立即与线粒体内的NADH量成比例增加，并且出现高强度和低强度NADH的混合物（数百微米大小）的斑片状图案。同时用分子示踪剂测量血流分布也显示了空间异质性，每个斑点区域的大小在几百微米量级，这与用NADH荧光观察到的斑块面积几乎相同。此外，在心肌微循环水平上测量的尺寸为100微米的微应变也显示出心脏表面的不均匀性。综合分析，血流、代谢功能障碍和微应变之间存在着分布关系。说明外源性心肌缺血面积与血液分布及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.