急性运动中线粒体能量转换调节的生物力能学分析:ROS和UCP3的作用

Bioenergetic Implications of Regulation of Mitochondrial Energy Transferring during Acute Exercise: The Role of ROS and UCP3

目的:研究1次耐力性运动过程中,骨骼肌线粒体ROS生成与UCP3表达与线粒体生物力能学改变的关系,及其在线粒体能量转换调控中的作用。方法:建立SD大鼠3级递增负荷跑台运动实验模型,分别以安静态、运动45min、90min、120min和150min时为实验观察点(time course),测定骨骼肌线粒体ROS生成,膜电位水平,态4呼吸速率,ATP合成速率,线粒体解偶联蛋白3(UCP-3)mRNA及其蛋白表达。结果:运动过程中ROS生成呈先升高后下降的变化趋势,运动120min时达峰值,其中运动45min、90min、120min和150min时ROS生成均较安静时显著升高(P<0·05,P<0·001,P<0·001和P<0·01),运动150min时ROS生成较120min时显著下降(P<0·001)。态4呼吸速率亦呈先升高后下降的并行性变化趋势,其中运动90和120min时较安静时显著增加(P<0·01和P<0·001),并于120min时达到峰值,150min时较120min时显著降低(P<0·001)。各实验观察点大鼠线粒体膜电位无显著差异(P>0·05)。ATP合成速率于运动45min时增加随后减小,150min时较45min时显著减小。UCP3mRNA和蛋白表达水平总体呈升高趋势,其中UCP3mRNA表达在运动至90min、120min及150min时均较安静时显著升高(P<0·001,P<0·01和P<0·01),其蛋白表达水平升高相对滞后一个时间段,在运动至120min及150min时较安静时显著升高(均P<0·001)。结论:一次性耐力运动初期ROS大量产生这一过程使线粒体膜维持适宜的跨膜电位,线粒体ATP合成速率降低是ROS线粒体能量转换过程调节线粒体功能的初始环节。随着ROS大量生成,其可能通过“ROS-质子漏”和“ROS-UCP3-质子漏”两条途径在运动中线粒体能量转换的精确调控中起“分子开关”作用,并作为始动因素参与了呼吸链电子传递与能量转换的能量分配的反馈调节,调控ATP生成。

Aims The purpose of present study was to investigate the bioenergetic implications of effects of ROS generation and UCP3 expression on the regulation of mitochondrial energy transferring during acute exercise. Methods SD rats were divided into 5 groups： resting group and exercise groups running for 45, 90, 120 and 150min respectively on the treadmill according to the Bedford＇s incremental protocol and they were sacrificed at rest or immediately after exercise for above pre - setting time course. The following parameters were determined： （1） ROS generation, state 4 rate, transmembrane potential and ATP synthesis rate of separated mitochondria; （2） Expression of UCP3 mRNA in muscle homogenate and its protein in mitochondria. Results （1） Mitochondrial ROS generation were significantly higher at 45, 90 and 120min than at rest （P 〈 0.05, P 〈0.001, and P 〈 0.001, respectively） with the peak at the point of 120min, then obviously declined at 150rain subsequently （P 〈 0.001 ）. （2） In a parallel change, state 4 rate increased significantly after exercising for 90 and 120min （ P 〈 0.01 and P 〈 0.001, respectively） and lowered after exercising for 150min （ P 〈 0.001 ）. （3） There was not significant change in the transmembrane potential. （4）The ATP synthesis rate increased at 45rain （ P 〈 0.05）and then decreased. （5） There were remarkably higher levels of UCP3 mRNA at 90, 120 and 150min （ P 〈 0.001, P 〈 0.01 and P 〈 0.01, respectively）, and following UCP3 protein contents increased at 120 and 150min （both P 〈 0.001 ）. Conclusions We hypothesize that ROS generation itself is the re - distribution of electron flux and a protection mechanism of the mitochondrial function by keeping the proper transmembrane potential and it is the initial effect of ROS generation in the regulation of mitochondrial energy transferring. During exercise ROS may serve as a ＇Molecular Switch＇ which lead to direct and indirect electric leak by activated proton conductance of UCP3 and as the initial factor involving the feedback regulation between respiratory chain electron transport and mitochondrial energy transferring procedure.