1Department of Anesthesia, Copenhagen Muscle Research Center, Rigshospitalet, Copenhagen, Denmark.
J Appl Physiol (1985). 2009 Dec;107(6):1799-805. doi: 10.1152/japplphysiol.00468.2009. Epub 2009 Sep 24.
Activation-induced increase in cerebral blood flow is coupled to enhanced metabolic activity, maybe with brain tissue redox state and oxygen tension as key modulators. To evaluate this hypothesis at the onset of exercise in humans, blood was sampled at 0.1 to 0.2 Hz from the radial artery and right internal jugular vein, while middle cerebral artery mean flow velocity (MCA V(mean)) was recorded. Both the arterial and venous lactate-to-pyruvate ratio increased after 10 s (P < 0.05), and the arterial ratio remained slightly higher than the venous (P < 0.05). The calculated average cerebral capillary oxygen tension decreased by 2.7 mmHg after 5 s (P < 0.05), while MCA V(mean) increased only after 30 s. Furthermore, there was an unaccounted cerebral carbohydrate uptake relative to the uptake of oxygen that became significant 50 s after the onset of exercise. These findings support brain tissue redox state and oxygenation as potential modulators of an increase in cerebral blood flow at the onset of exercise.
激活诱导的脑血流增加与增强的代谢活性相关，可能以脑组织氧化还原状态和氧张力作为关键调节剂。为了在人类运动开始时评估这一假说，从桡动脉和右颈内静脉以 0.1 至 0.2 Hz 的频率采集血液，同时记录大脑中动脉平均血流速度 (MCA V(mean))。在 10 秒后，动脉和静脉乳酸/丙酮酸比值均升高 (P < 0.05)，且动脉比值仍略高于静脉比值 (P < 0.05)。计算得出的平均脑毛细血管氧张力在 5 秒后下降了 2.7 mmHg (P < 0.05)，而 MCA V(mean)仅在 30 秒后才增加。此外，与氧摄取相比，在运动开始后 50 秒出现了未被解释的脑碳水化合物摄取，这一现象具有统计学意义。这些发现支持脑组织氧化还原状态和氧合作为运动开始时脑血流增加的潜在调节剂。
