[Effect of hyperbaric oxygen treatment on mitochondrial free radicals after transient focal cerebral ischemia in rats].

Objective: To investigate the effect of hyperbaric oxygen(HBO)therapy on mitochondrial free radicals after transient focal cerebral ischemia in rats.

Methods: The male SD rats were randomly assigned into two groups, control and HBO groups. All animals were subjected to 90 min intra-luminal middle cerebral artery occlusion (MCAO) with the regional cerebral blood flow monitored in vivo by laser Doppler flowmetry. HBO treatment was performed in a pressure chamber with 100% O(2)(3 ATM 1 h) 3 h after ischemia. Twenty-four hours after ischemia, mitochondria in the ischemic core and penumbra were isolated and the contents of H(2)O(2), O(2)(*-), MDA, SOD, GSH-PX and GSH in mitochondria were measured respectively.

Result: After cerebral ischemia-reperfusion, contents of mitochondrial H(2)O(2), O(2)(*-), MDA increased, while the SOD, GSH-PX and GSH in the mitochondria decreased significantly both in the ischemic core and the ischemic penumbra, compared with those in the normal controls(P<0.05). In the ischemic penumbra, HBO therapy increased significantly the content of O(2)(*-)(P<0.05), enhanced the activity of SOD, and decreased the level of MDA (P<0.05). However, HBO therapy did not change the level of MDA, though it also increased the content of O(2)(*-) and the activity of SOD in the ischemic core. HBO therapy had no significant effect on the contents of H(2)O(2), GSH-PX and GSH in the ischemic mitochondria.

Conclusion: HBO therapy initiated early after acute transient cerebral ischemia in rats can increase the mitochondrial free radicals level, but also increase the activity of the anti-radical enzymes. HBO treatment inhibits the lipid peroxidation damage of mitochondria in the ischemic penumbra, but not in the ischemic core, which indicates that the mitochondrial function plays a role in the reaction of the free radical in the ischemic area after HBO therapy.