Induction of apoptosis during the early phase of reperfusion after rat liver ischemia

This study was designed to investigate the induction of apoptosis during the reperfusion phase following warm liver ischemia in vivo. We evaluated apoptotic bodies (ABs) in sections stained with hematoxylin and eosin (H. E.) and positive hepatocytes in sections stained by the in situ nick end labeling method (TUNEL method) during the reperfusion phase up to 48 h after a 70% liver ischemia for 30 or 60min in duration (30 or 60 min group). The peak number of ABs in H. E.-stained sections was observed at 1 to 3 h in the 30 min group and 3 to 6 h in the 60 min group. The number of ABs gradually fell as the length of the perfusion period increased, and few ABs were observed at 24 and 48 h after reperfusion. A peak number of TUNEL-positive hepatocytes was recognized at 3 h after reperfusion in both groups, after which the numbers decreased gradually. DNA extracted from both groups was electrophoresed on a 1.5% agarose gel. In both groups, a ladder-like pattern over smear pattern was recognized at 3 h after reperfusion. These results show that hepatocyte apoptosis was induced during the early phase of reperfusion after rat liver ischemia morphologically and biochemically, which suggests that hepatocyte apoptosis may be associated with ischemia and reperfusion injury.