Muscle pump-induced inhibition of sympathetic vasomotor outflow during low-intensity leg cycling is attenuated by muscle metaboreflex activation
Muscle pump-induced inhibition of sympathetic vasomotor outflow during low-intensity leg cycling is attenuated by muscle metaboreflex activation
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DOI：
10.1152/japplphysiol.00639.2019
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发表时间：
2020-01-01
影响因子：
3.3
通讯作者：
Fadel, Paul J.
中科院分区：
文献类型：
--
作者：
Katayama, Keisho;Barbosa, Thales C.;Fadel, Paul J.
肌肉交感神经活动（MSNA）在低强度的腿部骑行过程中减少，因为肌肉泵诱导的静脉回流增加和心肺压力感受器的负荷增加。然而，当运动强度超过中等强度或持续时间较长时，MSNA在腿部循环期间增加，这表明心肺压力反射的交感神经抑制作用可以被强大的交感神经兴奋性驱动（如骨骼肌代谢反射）所覆盖。因此，我们测试的假设，高强度肌肉代谢反射激活减弱肌肉泵诱导的抑制MSNA在腿部自行车。MSNA（左桡神经）在运动后缺血（PEI）低（PEI-L）和高（PEI-H）强度等长握力运动（分别为20%和40%最大自主收缩）后，在前臂肌肉代谢反射的分级隔离过程中记录。单独和在每次PEI试验（PEI-L+Cycling，PEI-H+Cycling）期间进行腿部循环（15-20 W）。单独骑自行车诱导MSNA爆发频率（BF）和总活性（TA）显著降低。在PEI-L期间进行循环时，MSNA BF和TA也降低。然而，PEI-L +循环期间MSNA的降低幅度[Δ BF：-19 +/- 2%（P < 0.001），Delta TA：-25 +/- 4%（P < 0.001）;平均值+/- SE]小于单独骑自行车期间的值[Δ BF：-39 +/- 5%（P = 0.003），Δ TA：-45 +/- 5%（P = 0.002）]。更重要的是，在PEI-H循环期间MSNA没有降低[Δ BF：-1 +/-2%（P = 0.845），Δ TA：+2 +/-3%（P = 0.959）]。这些结果表明，肌肉泵引起的抑制交感神经血管流出在低强度的腿周期是衰减肌肉代谢反射激活强度依赖mathematicity-dependent mathematicity.NEW &注：有没有可用的数据之间的相互作用的肌肉泵引起的心肺压力反射负荷在腿周期和交感神经兴奋的影响肌肉代谢反射的交感神经抑制作用。在这项研究中，肌肉代谢反射激活减弱抑制肌肉交感神经活动（MSNA）在腿部循环。这可以部分解释MSNA对分级强度动态运动的反应，其中低强度腿部骑行抑制MSNA，而高强度运动增强分级交感神经兴奋。
Muscle sympathetic nerve activity (MSNA) decreases during leg cycling at low intensity because of muscle pump-induced increases in venous return and loading of the cardiopulmonary baroreceptors. However, MSNA increases during leg cycling when exercise is above moderate intensity or for a long duration, suggesting that the sympathoinhibitory effect of the cardiopulmonary baroreflex can be overridden by a powerful sympathoexcitatory drive, such as the skeletal muscle metaboreflex. Therefore, we tested the hypothesis that high-intensity muscle metaboreflex activation attenuates muscle pump-induced inhibition of MSNA during leg cycling. MSNA (left radial nerve) was recorded during graded isolation of the muscle metaboreflex in the forearm with postexercise ischemia (PEI) after low (PEI-L)- and high (PEI-H)-intensity isometric handgrip exercise (20% and 40% maximum voluntary contraction, respectively). Leg cycling (15-20 W) was performed alone and during each PEI trial (PEI-L+Cycling, PEI-H+Cycling). Cycling alone induced a significant decrease in MSNA burst frequency (BF) and total activity (TA). MSNA BF and TA also decreased when cycling was performed during PEI-L. However, the magnitude of decrease in MSNA during PEI-L +Cycling [Delta BF: -19 +/- 2% (P < 0.001), Delta TA: -25 +/- 4% (P < 0.001); mean +/- SE] was less than that during cycling alone [Delta BF: - 39 +/- 5% (P = 0.003), Delta TA: -45 +/- 5% (P = 0.002)]. More importantly, MSNA did not decrease during cycling with PEI-H [Delta BF: - 1 +/- 2% (P = 0.845), Delta TA: +2 +/- 3% (P = 0.959)]. These results suggest that muscle pump-induced inhibition of sympathetic vasomotor outflow during low-intensity leg cycling is attenuated by muscle metaboreflex activation in an intensity-dependent manner.NEW & NOTEWORTHY There are no available data concerning the interaction between the sympathoinhibitory effect of muscle pump-induced cardiopulmonary baroreflex loading during leg cycling and the sympathoexcitatory influence of the muscle metaboreflex. In this study, muscle metaboreflex activation attenuated the inhibition of muscle sympathetic nerve activity (MSNA) during leg cycling. This may explain, in part, the response of MSNA to graded-intensity dynamic exercise in which low-intensity leg cycling inhibits MSNA whereas high-intensity exercise elicits graded sympathoexcitation.