运动性疲劳的线粒体膜分子机理研究.III.线粒体质子跨膜势能与运动性内源自由基生成的关系

Study on Molecular Mechanism of Exercise-induced Fatigue in Mitochondrial Membrane.III.Relationship between Proton Potential Energy across Membrane and Generation of Free Radicals during Acute Exercise

目的 :以外源性补充线粒体电子传递载体CoQ10 为干预手段 ,观察一次急性运动后线粒体能量转换速率与线粒体脂质过氧化水平改变的关系 ,进一步探讨运动性内源自由基生成和代谢的途径及可能机理。方法 :雄性SD大鼠 2 4只 ,随机分为 1)正常对照组 (NC ,n =6 ) ;2 )正常运动组 (NE ,n =6 ) ;3)单纯补充CoQ10 对照组 (QC ,n =6 ) ;4)补充CoQ10 运动组 (QE ,n =6 )。以递增负荷达次最大强度急性运动为运动模型 ,测定运动后即刻肝脏线粒体膜CoQ10 和CoQ9结合含量 ,线粒体膜质子泵出与电子传递比值 (H+ / 2e)以及线粒体MDA含量。结果 :(1)NE、QC和QE组线粒体MDA含量均较NC组显著增高 (P <0 .0 5 ) ;(2 )线粒体H+ / 2e呈现与MDA含量相同的显著性变化 (P <0 0 5 ) ;(3)QC和QE组线粒体膜CoQ10 结合含量均较未补充的NC和NE组显著增高 (P <0 0 5 ) ,而线粒体膜内源CoQ9含量则在运动组 (NE和QE)呈显著增高 (P <0 0 5 )。结论 :线粒体膜CoQ结合含量和 /或动员的增加明显提高电子传递和质子跨膜偶联速率。运动性内源自由基生成可能与呼吸链电子流被所建立的高跨膜质子电化学势能抑制 ,而经电子漏途径代谢的能量重新分配有关。

Objective In order to further explore the possible mechanism of exercise-induced endogenous free radicals including their regeneration and metabolic pathway, we observed the effect of exogenous CoQ supplement on hepatic mitochondria energy transforming rate and lipid peroxidantion after an acute exercise.Methods SD rats were forced to run on treadmill using Bedford three-step increamental protocol.The animals were divided into four groups:1.Normal rest control(NC);2.CoQ supplement control(QC).3.Endurance exercise control(EC);4.Supplement of CoQ combined with exercise (QE).Following parameters after exercise were determined:1.The rate of proton pump out and electron transfer of respiratory chain complex Ⅱ+Ⅲ(H +/2e) in the present of Succinate;2.The binding content of exogenous CoQ 10 and endogenous CoQ 9 content in mitochondrial membrane;3.Mitochondrial MDA contents.Results The supplement of exogenous CoQ 10 caused a significant increase in binding CoQ 10 content of QC and QE compared with NC(P<0.05,respectively),and the exercise stress caused enhancing of endogenous CoQ 9 contents in both NE and QE groups(P<0.05,respectively).There were significant increase of mitochomdrial H +/2e in QC,QE and NE compared with NC(P<0.05,respectively).Meanwhile,the mitochondrial MDA contents in QC,QE and NE were higher than those in NC(P<0.05,respectively).ConclusionThe enhanced exogenous CoQ 10 binding into mitochondria and/or enhanced mobilization of endogenous CoQ 9 within mitochondria as the vital electron transfer carriers increased the coupling rate of proton pump out and electron transfer in respiratory chain.However,higher H + proton electron-chemistry potential energy outside membrane could inhibite the electron flows through respiratory chain,which might be linked via electron leak pathway.This redistributing of energy could be responsible to the regeneration of exercise-induced endogenous free radicals.