Renal tissue damage and apoptosis. Tubular vacuolation, protein casts, severe inflammatory infiltration as well as haemorrhage were seen in the IR group. In contrast, less tissue damage was seen after rapamycin treatment (A). The score of kidney damage assessed in HE sections at 400× magnification showed that Rapamycin significantly ameliorated kidney damage compared with IR group (B). Apoptotic cells were detected by ISEL fragmented DNAs at 400× magnification. They were hardly seen sham group, but increased after IR injury, which were markedly decreased after Rapamycin treatment (C). The number of apoptotic cells was remarkably higher in IR group than in Rapa group (D). Data are expressed as mean ± SD (n = 5).