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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。
Objective: To observe the effects of different intensity exercises on the functional anti-sympathetic activity of skeletal muscle and to explore the role of nitric oxide (NO) in it. Methods: Forty-five male Sprague-Dawley rats were randomly divided into 4 groups: quiet control group (C), moderate intensity exercise group (ME) and high intensity exercise group (HE) High-intensity treadmill, a total of 8 weeks. Vasoconstriction was induced in the lumbar sympathetic nerves by electrical stimulation (2 Hz and 5 Hz) after anesthesia in rats. The tibial nerve was stimulated by electrical stimulation (twice the threshold of motion and 5.5 times of exercise threshold) to induce moderate and high intensity contraction of the triceps. The changes of femoral vascular electrical conductivity (FVC) induced by sympathetic nerve stimulation in the quiet state and during the process of muscle contraction were recorded. The functional anti-sympathetic activity was expressed as the difference between the rate of change of sympathetic electrical stimulation response and the muscle contraction (Δ% FVC). Results: 1) △% FVC: moderate skeletal muscle contraction, the sympathetic nerve stimulation for the 2 Hz, HE group △% FVC was higher than the C group and the ME group (P <0.05); sympathetic nerve stimulation at 5 Hz, △ FVC in HE group was higher than that in C group (P <0.05). (P <0.05). The △% FVC in HE group was higher than that in ME group (P <0.05). Sympathetic nerve stimulation At 5 Hz stimulation, △% FVC in HE and ME groups was higher than that in C group (P <0.05). (2) The content of NO in plasma: Compared with resting group, the content of NO in plasma of each group increased in medium intensity contraction and high intensity contraction (P <0.05); Compared with moderate intensity contraction, Plasma NO levels were increased (P <0.05). Compared between the two groups, plasma NO levels were higher in ME group and HE group than those in C group (P <0.05), while those in HE group were higher than those in ME group (P <0.05) The ME group and HE group were higher than C group (P <0.05). Conclusion: Exercise can improve the functional anti-sympathetic activity of skeletal muscle and exert exercise intensity-dependent. The mechanism may be related to NO-induced signal transduction pathway to induce vasodilation.