Protective Effects of $\alpha$-Tocopherol and Ischemic Preconditioning on Hepatic Reperfusion Injury

This study evaluated the effect of $\alpha$-tocopherol ($\alpha$-TC), ischemic preconditioning (IPC) or a combination on the extent of mitochondrial injury caused by hepatic ischemia/reperfusion (I/R). Rats were pretreated with $\alpha$-TC (20 mg/kg per day, i.p.) for 3 days before sustained ischemia. A rat liver was preconditioned with 10 min of ischemia and 10 min of reperfusion, and was then subjected to 90 min of ischemia followed by 5 h or 24 h of reperfusion. I/R increased the aminotransferase activity and mitochondrial lipid peroxidation, whereas it decreased the mitochondrial glutamate dehydrogenase activity. $\alpha$-TC and IPC individually attenuated these changes. $\alpha$-TC combined with IPC ($\alpha$-TC+IPC) did not further attenuate the changes. The mitochondrial glutathione content decreased after 5 h reperfusion. This decrease was attenuated by $\alpha$-TC, IPC, and $\alpha$-TC+IPC. The significant production of peroxides observed after 10 min reperfusion subsequent to sustained ischemia was attenuated by $\alpha$-TC, IPC, and $\alpha$-TC+IPC. The mitochondria isolated after I/R were rapidly swollen. However, this swelling rate was reduced by $\alpha$­TC, IPC, and $\alpha$-TC+IPC. These results suggest that either $\alpha$-TC or IPC reduces the level of mitochondrial damage associated with oxidative stress caused by hepatic I/R, but $\alpha$- TC combined with IPC offers no significant additional protection.