On the contribution of group III and IV muscle afferents to the circulatory response to rhythmic exercise in humans
On the contribution of group III and IV muscle afferents to the circulatory response to rhythmic exercise in humans
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DOI：
10.1113/jphysiol.2011.209353
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发表时间：
2011-08-01
影响因子：
5.5
通讯作者：
Richardson, Russell S.
中科院分区：
文献类型：
--
作者：
Amann, Markus;Runnels, Sean;Richardson, Russell S.
我们研究了人体节律性运动中骨骼肌传入反馈在循环控制中的作用。9名健康男性在对照组(Ctrl)和腰椎鞘内注射芬太尼的情况下进行单腿伸膝运动(15/30/45W，每3min)，腰椎鞘内注射芬太尼削弱了Mu阿片受体敏感的肌肉传入。在每项工作的最后一分钟测定心输出量和股血流量，并采集股动脉/静脉血样本。为了排除芬太尼向脑干的头侧迁移，我们记录了对不同水平的高碳酸血症的静息呼吸反应没有变化。静息状态下的血流动力学没有差异。然而，在运动期间，芬太尼阻滞组的心输出量与对照组相比降低了20%(P<；0.05)，其次是心率和每搏量分别降低了6%和13%。在整个运动过程中，平均动脉压(MAP)降低了7%(P<；0.01)，这可能是导致股骨血流量下降15%的原因之一。然而，MAP并不是这种外周血流动力学改变的完全原因，因为血管传导性也减弱(类似于9%)。去甲肾上腺素溢出增加的证据(P=0.09)暗示交感神经流出增加。在使用芬太尼的运动中，股骨血流量的减少与腿部氧气供应减少17%(P<；0.01)和随之而来的动静脉氧气差增加(4-9%)相关，但腿部氧气消耗仍然比对照组低7-13%(P<；0.05)。我们的发现揭示了持续的肌肉传入反馈对确保人类对有节奏的运动做出适当的血流动力学和最终的代谢反应的重要贡献。
We investigated the role of skeletal muscle afferent feedback in circulatory control during rhythmic exercise in humans. Nine healthy males performed single leg knee-extensor exercise (15/30/45 watts, 3 min each) under both control conditions (Ctrl) and with lumbar intrathecal fentanyl impairing mu-opioid receptor-sensitive muscle afferents. Cardiac output and femoral blood flow were determined, and femoral arterial/venous blood samples were collected during the final minute of each workload. To rule out cephalad migration of fentanyl to the brain-stem, we documented unchanged resting ventilatory responses to different levels of hypercapnia. There were no haemodynamic differences between conditions at rest. However, during exercise cardiac output was similar to 20% lower with fentanyl blockade compared to control (P < 0.05), secondary to a 6% and 13% reduction in heart rate and stroke volume, respectively. Throughout exercise mean arterial pressure (MAP) was reduced by 7% (P < 0.01) which is likely to have contributed to the 15% fall in femoral blood flow. However, MAP was not completely responsible for this peripheral haemodynamic change as vascular conductance was also attenuated (similar to 9%). Evidence of increasing noradrenaline spillover (P = 0.09) implicated an elevation in sympathetic outflow in this response. The attenuated femoral blood flow during exercise with fentanyl was associated witha 17% reduction in leg O-2 delivery (P < 0.01) and a concomitant rise in the arteriovenous O-2 difference (4-9%), but leg O-2 consumption remained 7-13% lower than control (P < 0.05). Our findings reveal an essential contribution of continuous muscle afferent feedback to ensure the appropriate haemodynamic and ultimately metabolic response to rhythmic exercise in humans.