Masuki Shizue, Nose Hiroshi
Department of Sports Medical Sciences, Institute on Aging and Adaptation, Shinshu University Graduate School of Medicine, Matsumoto 390-8621, Japan.
J Physiol. 2003 Nov 15;553(Pt 1):191-201. doi: 10.1113/jphysiol.2003.047530. Epub 2003 Aug 22.
To assess the role of arterial baroreflex control in muscle blood flow (MBF) and voluntary locomotion, mean arterial pressure (MAP), MBF, and electromyograms (EMGs) were measured in freely moving mice before (CNT) and after blocking the afferent or efferent pathway of arterial baroreflexes, carotid sinus denervation (CSD), or intraperitoneal administration of phentolamine (BLK), respectively. MAP was measured through a catheter placed in the femoral artery. MBF was measured with a needle-type laser-Doppler flowmeter and recorded through a low-pass filter with an edge frequency of 0.1 Hz. The frequency and duration of locomotion were judged from EMG recordings in the hindlimb. These probes were implanted at least 2 days before the measurements. Muscle vascular conductance (MVC = MBF/MAP) in all groups started to rise within 1 s after the onset of locomotion, but the increasing rate in CSD and BLK was significantly higher than in CNT for the first 9 s (P < 0.001). MAP in CSD and BLK significantly decreased below the baseline within 1 s and this was highly correlated with the increase in MVC for the first 9 s (R2 = 0.842, P < 0.001), whereas MAP in CNT increased significantly 8 s after the onset of locomotion. Although the total period of movement in a free-moving state for 60 min was not significantly different between CNT and CSD (P > 0.1), the frequency of movement with a short duration of 0.1-0.4 min was higher in CSD than in CNT (P < 0.001), which was highly correlated with the reduction in MAP accompanying each period of movement (R2 = 0.883, P < 0.01). These results suggest that arterial baroreflexes suppress vasodilatation in contracting muscle to maintain MAP at the onset of voluntary locomotion, and are necessary to continue a given duration of locomotion in mice.
为评估动脉压力反射控制在肌肉血流（MBF）和自主运动中的作用，分别在阻断动脉压力反射的传入或传出通路、进行颈动脉窦去神经支配（CSD）或腹腔注射酚妥拉明（BLK）之前（CNT）和之后，对自由活动的小鼠测量平均动脉压（MAP）、MBF和肌电图（EMG）。MAP通过置于股动脉的导管进行测量。MBF用针型激光多普勒血流仪测量，并通过边缘频率为0.1 Hz的低通滤波器进行记录。根据后肢的EMG记录判断运动的频率和持续时间。这些探头在测量前至少植入2天。所有组的肌肉血管传导率（MVC = MBF/MAP）在运动开始后1秒内开始上升，但在最初的9秒内，CSD组和BLK组的上升速率显著高于CNT组（P < 0.001）。CSD组和BLK组的MAP在1秒内显著降至基线以下，这与最初9秒内MVC的增加高度相关（R2 = 0.842，P < 0.001），而CNT组的MAP在运动开始后8秒显著增加。尽管CNT组和CSD组在自由活动状态下60分钟的总运动时间没有显著差异（P > 0.1），但持续时间为0.1 - 0.4分钟的短时间运动频率在CSD组高于CNT组（P < 0.001），这与每个运动周期伴随的MAP降低高度相关（R2 = 0.883，P < 0.01）。这些结果表明，动脉压力反射在自主运动开始时抑制收缩肌肉中的血管舒张以维持MAP，并且对于小鼠持续给定持续时间的运动是必要的。
