Buckwalter J B, Clifford P S
Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53295, USA.
Am J Physiol. 1999 Nov;277(5):H1872-7. doi: 10.1152/ajpheart.1999.277.5.H1872.
The purpose of this study was to determine whether the autonomic nervous system is involved in skeletal muscle vasodilation at the onset of exercise. Mongrel dogs (n = 7) were instrumented with flow probes on both external iliac arteries. Before treadmill exercise at 3 miles/h, 0% grade, hexamethonium (10 mg/kg) and atropine (0.2 mg/kg) or saline was infused intravenously. Ganglionic blockade increased resting heart rate from 87 +/- 5 to 145 +/- 8 beats/min (P < 0.01) and reduced mean arterial pressure from 100 +/- 4 to 88 +/- 5 mmHg (P < 0.01). During steady-state exercise, heart rate was unaffected by ganglionic blockade (from 145 +/- 8 to 152 +/- 5 beats/min), whereas mean arterial pressure was reduced (from 115 +/- 4 to 72 +/- 4 mmHg; P < 0.01). Immediate and rapid increases in iliac blood flow and conductance occurred with initiation of exercise with or without ganglionic blockade. Statistical analyses of hindlimb conductance at 5-s intervals over the first 30 s of exercise revealed a statistically significant difference between the control and ganglionic blockade conditions at 20, 25, and 30 s (P < 0.01) but not at 5, 10, and 15 s of exercise. Hindlimb conductance at 1 min of exercise was 9.21 +/- 0.68 and 11.82 +/- 1.32 ml. min(-1). mmHg(-1) for the control and ganglionic blockade conditions, respectively. Because ganglionic blockade did not affect the initial rise in iliac conductance, we concluded that the autonomic nervous system is not essential for the rapid vasodilation in active skeletal muscle at the onset of exercise in dogs. Autonomic control of skeletal muscle blood flow during exercise is manifested through vasoconstriction and not vasodilation.
本研究的目的是确定自主神经系统是否在运动开始时参与骨骼肌血管舒张。用杂种狗（n = 7），在双侧髂外动脉上安装流量探头。在以3英里/小时、0%坡度进行跑步机运动前，静脉注射六甲铵（10mg/kg）和阿托品（0.2mg/kg）或生理盐水。神经节阻断使静息心率从87±5次/分钟增加到145±8次/分钟（P<0.01），并使平均动脉压从100±4mmHg降低到88±5mmHg（P<0.01）。在稳态运动期间，心率不受神经节阻断的影响（从145±8次/分钟到152±5次/分钟），而平均动脉压降低（从115±4mmHg到72±4mmHg；P<0.01）。无论是否进行神经节阻断，运动开始时髂血流量和血管传导率立即迅速增加。对运动最初30秒内每隔5秒的后肢血管传导率进行统计分析，结果显示在运动20、25和30秒时，对照和神经节阻断条件之间存在统计学显著差异（P<0.01），但在运动5、10和15秒时无差异。运动1分钟时，对照和神经节阻断条件下后肢血管传导率分别为9.21±0.68和11.82±1.32ml·min-1·mmHg-1。由于神经节阻断不影响髂血管传导率的初始升高，我们得出结论，自主神经系统对于狗运动开始时活跃骨骼肌的快速血管舒张不是必需的。运动期间骨骼肌血流的自主控制通过血管收缩而非血管舒张表现出来。
