ABSTRACT
The study objective was to investigate time dependent effects of ischemic-reperfusion on cardiomyocyte apoptosis. Male Sprague-Dawley rats [270-330 gr] were randomly divided into four groups [n=10] and anesthetized by sodium pentobarbital [50-60 mg/kg-IP]. The hearts of rats in each of three treatment groups were removed and quickly mounted on a Langendorff apparatus and perfused by a modified Krebs-Henseleit solution under constant pressure at 37 degree C. During the stabilization time, 30 minute regional ischemia [which was followed with 60, 90 or 120 minute reperfusion in respective T/60min, T/90 min and T/120 min reperfusion groups] was established, while in the control group the hearts were intact. Immunohistochemical detection of apoptotic cells was performed using an in-situ cell death detection [TUNEL] kit. The positive cardiomyocytes counted in five random high power fields in each sample. Data were presented as mean +/- SEM for each group. In the control group, the number of apoptotic cells was 1.0 +/- 0.4, while in the treatment groups of T/60min, T/90 min and T/120 min reperfusion, the corresponding numbers were 2.0 +/- 0.5, 3.0 +/- 0.3 and 6.0 +/- 0.3, respectively. Although the difference between T/60 min and T/90 min and T/60 min and control group was not significant [p>0.05], the difference between T/60 min and T/120 min [p<0.001], T/90 min and T/120 min [p<0.01], T/90 min and control [p<0.01] and T/120 min and control [p<0.001] was significant. We demonstrated that the duration of ischemic-reperfusion insult can affect the apoptosis changes in cardiomyocytes