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

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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.