Peltonen Juha E, Paterson Donald H, Shoemaker J Kevin, Delorey Darren S, Dumanoir Gregory R, Petrella Robert J, Kowalchuk John M
Unit for Sports and Exercise Medicine, Institute of Clinical Medicine, University of Helsinki, Paasikivenkatu 4, 00250 Helsinki, Finland.
Respir Physiol Neurobiol. 2009 Oct 31;169(1):24-35. doi: 10.1016/j.resp.2009.08.013. Epub 2009 Sep 1.
To examine if cerebral (frontal cortex) and skeletal muscle (m. vastus lateralis) deoxygenation and cerebral blood flow velocity (V(mean)) in the middle cerebral artery differentiated between normoxic and hypoxic (end-tidal P(O)(2) 71 mmHg) conditions, and if they were associated with hypoxic ventilatory chemosensitivity and cerebrovascular responsiveness, 8 men performed incremental cycling trials (30W/min ramp) under normoxic (T1-N) and hypoxic (T1-H) conditions until volitional fatigue, or until arterial O2 saturation decreased below 80%. The tests were repeated (T2-N; T2-H) on another day with supplemental O2 (Sup-O2) at the end of exercise. The V(mean) response was similar in normoxia and hypoxia. In hypoxia compared to normoxia, cerebral deoxygenation ( upward arrow deoxyhemoglobin concentration (Delta[HHb]) and downward arrow tissue oxygenation index (TOI)) was greater at a given work rate. A strong hypoxic ventilatory chemosensitivity was associated with a rapid reduction of cerebral TOI (r=0.94, P<0.001). Muscle deoxygenation was similar in normoxia and hypoxia suggesting greater muscle blood flow in hypoxia compared to normoxia and thus the existence of control features that match muscle perfusion and O2 delivery tightly with O2 demand during exercise. Sup-O2 reduced both cerebral and muscle deoxygenation, at least transiently.
为了研究大脑（额叶皮质）和骨骼肌（股外侧肌）的脱氧情况以及大脑中动脉的脑血流速度（V(mean)）在常氧和低氧（呼气末P(O)(2) 71 mmHg）条件下是否存在差异，以及它们是否与低氧通气化学敏感性和脑血管反应性相关，8名男性在常氧（T1-N）和低氧（T1-H）条件下进行递增式自行车试验（30W/分钟斜坡递增），直至自愿疲劳，或直至动脉血氧饱和度降至80%以下。在另一天运动结束时补充氧气（Sup-O2）的情况下重复进行测试（T2-N；T2-H）。常氧和低氧条件下V(mean)反应相似。与常氧相比，在低氧状态下，在给定工作率时大脑脱氧情况（脱氧血红蛋白浓度上升（Delta[HHb]）和组织氧合指数下降（TOI））更明显。强烈的低氧通气化学敏感性与大脑TOI的快速降低相关（r = 0.94，P < 0.001）。常氧和低氧条件下肌肉脱氧情况相似，这表明与常氧相比，低氧状态下肌肉血流量更大，因此存在在运动期间使肌肉灌注和氧气输送与氧气需求紧密匹配的控制机制。补充氧气至少在短期内降低了大脑和肌肉的脱氧情况。
