Analysis of abnormal coronary micro-circulation in a diabetic or hypertensive rat heart by simultaneous measurement of NADH fluorescence and blood flow distribution

我们的研究有两个特点。用烟酰胺腺嘌呤二核苷酸(NADH)荧光直接显示心肌细胞线粒体的低氧状态，用高分辨率、40微米和100微米的分子流示踪剂显示血流。本文测定了糖尿病大鼠缺血前后朗宁多夫制剂中紫外线激发的NADH荧光强度。我们通过将去甲基丙咪胺(~3H-DMI)灌流到心肌中来测量血流分布，然后将其切片并打印在成像板上。对冠脉微循环最重要的线粒体氧代谢和心肌血流分布进行一次性测量尚无先例研究。我们还研究了高血压大鼠，从NADH荧光研究中发现，心肌微循环中存在血流分布的不均一性，这种不均一性在缺血时会增强。分子示踪法证实了这一点。两种方法的微循环最小单位长度相同，约为400微米。在高血压的基础研究方面，不对称二甲基精氨酸(ADMA)水平与一氧化氮(NO)的产生显著高于对照组。在糖尿病大鼠的NADH荧光研究中，从常氧到低氧状态的时间常数趋于短，从低氧到常氧状态的时间常数趋于长。这支持了糖尿病大鼠的心脏易受缺血的影响。此外，缺血状态下的再灌注血流量与NO的产生密切相关。

There are two features of our study. Direct visualization of mitochondrial hypoxic state of the myocytes by nicotinamide adenine dinucleotide (NADH) fluorescence and blood flow visualization with molecular flow tracers with high resolution, 40 microns and 100 microns respectively. We mearsured NADH fluorescence intensity excited by ultraviolet ray in Langendorff preparation of diabetic rats with or without ischaemic condition. We measured blood flow distribution by perfusing tritiated desmethyl-imipramine (^3H-DMI) into the myocardium, which was later sliced and printed on an imaging plate. There is not any precedent study that measured at a time mitochondrial oxygen metabolism and myocardial blood flow distribution, which are most significant to coronary microcirculation. We also dealt with hypertensive rats in our study.From the NADH fluorescence study, we found that there is blood flow distribution heterogeneity in myocardial microcirculation, which is enhanced during ischaemia. This was confirmed by the molecular tracer method. The minimum unit length of microcirculation was in the same size in both methods, about 400 microns. As to basic research on hypertension, asymmetric dimethylarginine (ADMA) level was significantly elevated in relation to nitric oxide (NO) production compared with control rats. In NADH fluorescence study of diabetic rats, the time constant from normoxic to hypoxic state tended to be shorter and the time constant from hypoxic to normoxic state tended to be longer. This supports that diabetic rat hearts are vulnerable to ischaemia. In addition, reperfusion blood flow after ischaemic condition is deeply related to NO production.