Effects of Ischemic Preconditioning, Adenosine and Pinacidil on Expression of Apoptosis in the Rectus Femoris Muscles of the Rats after Ischemia and Timely Reperfusion

Kim, Byung Chun; Paik, Doo Jin; Ahn, Dong Choon; Cho, Won Gil; Lee, Kwan Hyung; Hwang, Kyu Sung; Chung, Ho Sam

Abstract

The ischemia and reperfusion injury of skeletal muscle is caused by generation of reactive oxygen species. Recently, apoptosis has been associated with oxidative stress in a number of cell systems. The effects of ischemic preconditoining in cardiac muscle have been established as rendering muscle tolerance to ischemic reperfusion damage via opening of KAPT channel and activation of adenosine A1 receptor. The effects and mechanisms of ischemic preconditioning are not known clearly. The present study was performed to investigate the effect and the mechanisms of ischemic preconditioning by measuring the incidences of apoptosis on timely reperfused ischemic muscles. The healthy Sprague -Dawley rats weighing from 200 g to 250 g were used as experimental animals. Under pentobarbital (50 mg/kg) anesthesia, lower abdominal incision was done and left common iliac artery was ligated by using vascular clamp for 2 hours. Rectus femoris muscles were obtained at 0 hour, 1 hour, 2 hours, 6 hours, 12 hours and 24 hours of reperfusion. The group of ischemic preconditioning underwent three episodes of 5 minutes occlusion and 5 minutes reperfusion of common iliac artery followed by 2 hours of ischemia and timely reperfusion. Adenosine (50 microgram/kg) or pinacidil (1 mg/kg) were administered intravenously before ischemia and 2 hours of ischemia and timely reperfusion was done. 6 microM of paraffin sections were obtained. The incidencies of apoptosis were observed by use of in situ apoptosis detection kit. The results obtained were as follows. 1. The reactivities to apoptosis in the rectus femoris muscle increased after 2 hours of ischemia and timely reperfusion. 2. After 2 hours of ischemia and timely reperfusion with ischemic preconditioning and the treatment of pinacidil, the reactivities to apoptosis in all groups decreased markedly. 3. After 2 hours of ischemia and timely reperfusion with the treatment of adenosine, the reactivities to apoptosis in all groups were similar to those in the group of 2 hours of ischemia and reperfusion. Consequently, these results suggest that the reactivities to apoptosis decrease after 2 hours of ischemia and timely reperfusion with ischemic preconditioning. The effect of ischemic preconditioning is related to opening of KATP channel partly.