| Summary: | 碩士 === 國立交通大學 === 應用化學系分子科學碩博士班 === 99 === Ischemia-reperfusion injury refers to the increased damage occurring to the tissue during reperfusion after a period of ischemia. Ischemia-reperfusion has long been recognized as the major complication of cardiac arrest, stroke, and organ transplantation, and remains one of the most active topics in fundamental biomedical research. The ability to evaluate timely the damage of tissue caused by ischemia-reperfusion is essential to understand to the pathogenesis. The knowledge produced is also important for the development of interventions to prevent or cure ischemia-reperfusion injury. By far, post-reperfusion histopathological examination remains a commonly employed method to assess ischemia-reperfusion injury. We have developed a minimally invasive, label-free, and real-time means to assess ischemia-reperfusion injury. By using an intravital microscope, we have obtained time-lapse autofluorescence images of rat liver during ischemia and reperfusion. We found the autofluorescence of the liver tissue decreased by 40-50 % rapidly during ischemia, but restored gradually during reperfusion. The rate and extent of recovery of the autofluorescence intensity during reperfusion depended strongly on the duration of ischemia. The autofluorescence intensity recovered to 90 % of the base line asymptotically and rapidly (<10 min) for short ischemia (20 min). In contrast, the recovery of the autofluorescence images exhibited heterogeneous patterns and the rate of recovery was significantly slower for long ischemic time (> 60 min). Moreover, we observed occasional or long-lasting no-reflow in some regions of this tissue. To elucidate the origin of the autofluorescence and to account the observation, we employed control experiments with inhibitors of mitochondria and flavin, and the results strongly suggested that the autofluorescence was produced from flavin bound to mitochondrial proteins. Based on the results, we further hypothesized that the spatiotemporal variation of autofluorescence images observed during ischemic-reperfusion was attributed to the conversion of flavin between the non-fluorescent reduced state and fluorescent oxidized state.
|
|---|
