不同强度运动对骨骼肌功能性抗交感活性的影响

Effects of Different Intensity Exercise on Activity of Functional Sympatholysis in Skeletal Muscle

目的:观察不同强度运动对骨骼肌功能性抗交感活性的影响,并探讨一氧化氮(NO)在其中的作用。方法:45只雄性SD大鼠随机分为安静对照组(C)、中等强度运动组(ME)和高强度运动组(HE),其中C组保持安静状态,ME组进行中等强度、HE组进行高强度跑台运动,共8周。大鼠麻醉后通过电刺激(2 Hz和5 Hz)腰部交感神经诱导血管收缩反应,电刺激(2倍运动阈和5.5倍运动阈)胫神经分别诱发小腿三头肌中等强度和高强度收缩。记录安静状态下以及肌肉收缩过程中交感神经电刺激引发股血管传导性(FVC)的变化,功能性抗交感活性用安静时FVC对交感神经电刺激反应的变化率与肌肉收缩时的差值表示(△%FVC)。结果:1)△%FVC:骨骼肌中等强度收缩,交感神经电刺激为2 Hz时,HE组△%FVC高于C组和ME组(P<0.05);交感神经电刺激为5 Hz时,HE组△%FVC高于C组(P<0.05)。肌肉高强度收缩,交感神经电刺激为2 Hz时,HE组和ME组△%FVC高于C组(P<0.05),HE组△%FVC高于ME组(P<0.05);交感神经电刺激为5 Hz时,HE组和ME组△%FVC高于C组(P<0.05)。2)血浆NO含量:组内与安静时比较,骨骼肌中等强度收缩时和高强度收缩时各组血浆NO含量均升高(P<0.05);与中等强度收缩时比较,高强度收缩时各组血浆NO含量均升高(P<0.05)。组间比较,安静时和中等强度收缩时血浆NO含量在ME组和HE组均高于C组(P<0.05),HE组高于ME组(P<0.05);高强度收缩时血浆NO含量在ME组和HE组均高于C组(P<0.05)。结论:运动可改善骨骼肌功能性抗交感活性并呈现运动强度依赖性,其机制可能与NO介导的信号转导途径诱导血管舒张反应有关。

Purpose：The purpose of this study was to observe the effects of different intensity exercise on activity of functional sympatholysis in skeletal muscle and to investigate the role of nitric oxide（NO）in this process.Methods：Forty-five male SD rats were randomly divided into control（C）,moderate-intensity exercise（ME）and highintensity exercise（HE）groups;rats of C group maintained rest state while those of ME group and HE group performed 8-week moderate or high intensity treadmill running exercise respectively.Rats were anaesthetized and suffered stimulation of the lumbar sympathetic chain（2 Hz and 5 Hz）;the triceps surae was contracted rhythmically（moderate intensity and high intensity respectively）by electric stimulation of sciatic nerve（2 times movement threshold and 5.5 times movement threshold）.The changes of femoral vascular conduction（FVC）induced by sympathetic nerve stimulation were tested at rest state and during contraction.The activity of functional sympatholysis was indicated by the difference of the FVC induced by sympathetic nerve stimulation at rest state and during contraction（△%FVC）.Results：1）△%FVC.HE group＇s%FVC was higher than that of C group and ME group when skeletal muscle was in moderate intensity contraction and sympathetic nerve stimulation was 2 Hz（P〈0.05）,HE group＇s%FVC was higher than that of C group when sympathetic nerve stimulation was 5 Hz（P〈0.05）.When skeletal muscle was in high intensity contraction and sympathetic nerve stimulation was 2 Hz,HE and ME groups＇%FVC was higher than that of C group（P〈0.05）,HE group＇s was higher than ME group＇s（P〈0.05）;when sympathetic nerve stimulation was 5 Hz,that of HE and ME groups＇was higher than that of C group（P〈0.05）.2）NO content in plasma.Compared with the rest state,NO content in plasma of all groups increased after moderate and high intensity contraction of skeletal muscles（P〈0.05）;compared with moderate intensity contraction,NO content in plasma of all groups increased after high intensity contraction（P〈0.05）.NO content in plasma of ME and HE groups was higher than that of C group at rest state and moderate intensity contraction（P〈0.05）,and that of HE group was higher than that of ME（P〈0.05）;it of ME and HE groups was higher than that of C group at high intensity contraction（P〈0.05）.Conclusions：Exercise can improve the activity of functional sympatholysis of skeletal muscle,which shows exercise intensity dependence;the mechanism may be related to vasodilation response induced by NO mediated signal transduction pathway.