Department of Physiology, Graduate School of Health Sciences, Hiroshima University, Hiroshima, Japan.
J Appl Physiol (1985). 2012 Jun;112(12):1961-74. doi: 10.1152/japplphysiol.00075.2012. Epub 2012 Apr 12.
Whether neurogenic vasodilatation contributes to exercise hyperemia is still controversial. Blood flow to noncontracting muscle, however, is chiefly regulated by a neural mechanism. Although vasodilatation in the nonexercising limb was shown at the onset of exercise, it was unclear whether central command or muscle mechanoreflex is responsible for the vasodilatation. To clarify this, using voluntary one-legged cycling with the right leg in humans, we measured the relative changes in concentrations of oxygenated-hemoglobin (Oxy-Hb) of the noncontracting vastus lateralis (VL) muscle with near-infrared spectroscopy as an index of tissue blood flow and femoral blood flow to the nonexercising leg. Oxy-Hb in the noncontracting VL and femoral blood flow increased (P < 0.05) at the start period of voluntary one-legged cycling without accompanying a rise in arterial blood pressure. In contrast, no increases in Oxy-Hb and femoral blood flow were detected at the start period of passive one-legged cycling, suggesting that muscle mechanoreflex cannot explain the initial vasodilatation of the noncontracting muscle during voluntary one-legged cycling. Motor imagery of the voluntary one-legged cycling increased Oxy-Hb of not only the right but also the left VL. Furthermore, an increase in Oxy-Hb of the contracting VL, which was observed at the start period of voluntary one-legged cycling, had the same time course and magnitude as the increase in Oxy-Hb of the noncontracting muscle. Thus it is concluded that the centrally induced vasodilator signal is equally transmitted to the bilateral VL muscles, not only during imagery of exercise but also at the start period of voluntary exercise in humans.
神经源性血管舒张是否有助于运动充血仍然存在争议。然而，非收缩肌肉的血流主要受神经机制调节。虽然在运动开始时已经显示出非运动肢体的血管舒张，但尚不清楚中枢指令还是肌肉机械反射负责这种血管舒张。为了阐明这一点，我们使用人类单腿自愿骑行，用右腿测量非收缩股外侧肌（VL）组织血流量的近红外光谱作为指标，测量非收缩 VL 和非运动腿股血流的相对变化。在自愿单腿骑行的起始期间，尽管动脉血压没有升高，但非收缩 VL 和股血流中的 Oxy-Hb 增加（P<0.05）。相比之下，在被动单腿骑行的起始期间，未检测到 Oxy-Hb 和股血流的增加，表明肌肉机械反射不能解释自愿单腿骑行中非收缩肌肉的初始血管舒张。自愿单腿骑行的运动想象增加了不仅右侧而且左侧 VL 的 Oxy-Hb。此外，在自愿单腿骑行的起始期间观察到的收缩 VL 中的 Oxy-Hb 增加与非收缩肌肉中的 Oxy-Hb 增加具有相同的时间过程和幅度。因此，结论是中枢诱导的血管扩张信号同样传递到双侧 VL 肌肉，不仅在运动想象期间，而且在人类自愿运动的起始期间也是如此。
