| Research Abstract |
This study was aimed to clarify the molecular biophsiological mechanisms of heart failure, and to clarify whether plasma sFas, an inhibitor of apoptosis, can improve the long-term prognosis of rat with old myocardial infarction, as a model of heart failure.
Experiments were performed on 30 6-wk-old male rat for suffering from heart failure caused by myocardial infarction, and the same number of rat for producing Sham operation, as a control. In 1999, we successfully performed to make a model of heart failure after acute myocardial infarction made by ligation of proximal site of left coronary artery.
In 2000, we measured the plasma sFas concentration in 12 weeks heart failure rat model after the myocardial infarction. As a result, plasma sFas was clarified to elevate in heart failure. In addition, in the cardiac muscle tissue of the rat, we recognized TUNEL positive myocytes which suggested existence of DNA fragmentation, as a marker of apoptosis, and upregulation of Fas and Bax, apoptosi
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s inducers. In findings of electron microscope of cardiac muscle tissue, hypertrophy and degeneration of myocytes and deformity of myocytic nucleus were observed. However, specific condensation of chromatin, shrinkage, budding, and apoptotic body of myocytes, which suggested apoptosis, was not observed.
We clarifled the findings of fibrosis in myocytes, which suggested myocyte cell death by optical microscope. In addition, the frequency of the myocytes showing TUNEL positive was equal to or less than 1%. Accordingly, the absence of apoptosis findings with electron microscope did not mean that there was not apoptosis in myocytes, but observation area by electron microscope was too small.
Subsequently, we performed to administrate sFas into the above heart failure rats via intraabdominal injection. However, we did not reach plasma sFas level to produce elevation of persistence of significance, and was not able to confirm improvement of heart failure. Because, turnover of plasma sFas is considered earlier unexpectedly in intraabdominal administration of sFas. Therefore, intraabdominal administration of sFas was not accepted for sFas expression extend over a long period of time. We concluded that gene therapy of sFas is necessary to realize continuous expression in myocardial tissue. Less
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