Hypericin as a Marker for Determination of Myocardial Viability in a Rat Model of Myocardial Infarction

The aim of this study was to investigate the necrosis-avid agent hypericin as a potential indicator for determination of myocardial infarction (MI). Male Sprague-Dawley rats (n = 30) weighing 350 +/- 20 g were subjected to acute reperfused MI. Animals were divided into four groups (n = 6), in which hypericin was intravenously injected at 0, 1, 2 and 5 mg kg(-1) respectively. One day after injection, rats were euthanized with their hearts excised for qualitative and quantitative studies by means of microscopic fluorescence examination to decide the dosage of hypericin. Another group was injected with hypericin at the decided dose and evaluated by fluorescence macroscopy in colocalization with triphenyltetrazoliumchloride (TTC) and histomorphology. Infarct-to-normal contrast ratio and relative infarct size were quantified. Hypericin-induced red fluorescence was significantly brighter in necrotic than in viable myocardium as proven by a six times higher mean fluorescence density. Mean MI area was 35.66 +/- 22.88% by hypericin fluorescence and 32.73 +/- 21.98% by TTC staining (R-2 = 0.9803). Global MI-volume was 34.56 +/- 21.07% by hypericin and 35.11 +/- 20.47% by TTC staining (R-2 = 0.9933). The results confirm that hypericin specifically labeled necrosis, and enhanced the imaging contrast between the infarcted and normal myocardium, suggesting its potential applications for the assessment of myocardial viability.