Effects of YS on SOD (A) and MDA (B) levels in liver tissues. After 90 min of ischemia and 6 h of reperfusion, liver tissues were homogenized and assayed for SOD and MDA levels as the index of hepatic oxidative stress. YS with different dose (5, 10, 20 mg/kg) was injected intraperitoneally 24 h and 1 h before ischemia and a third dose was injected intravenously just before reperfusion. For all groups, n = 8. bP < 0.01 compared with sham group; cP < 0.05, dP < 0.01 compared with I/R group.