C. G. Crandall: Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, 7232 Greenville Avenue, Dallas, TX 75231, USA.
Exp Physiol. 2013 Nov;98(11):1597-607. doi: 10.1113/expphysiol.2013.074104. Epub 2013 Jul 12.
This study tested the hypothesis that hyperthermia attenuates the increase in cerebral perfusion during cognitive activation. Mean middle cerebral artery blood velocity (MCAV(mean)) served as an index of cerebral perfusion, while the nBack test (a test of working memory) was the cognitive task. Hyperthermia was characterized by elevations (P < 0.001) in skin (by 5.0 ± 0.8 °C) and intestinal temperatures (by 1.3 ± 0.1 °C) and reductions (P < 0.020) in mean arterial pressure (by 11 ± 10 mmHg), end-tidal CO2 tension (by 3 ± 6 mmHg) and MCAV(mean) (by 10 ± 9 cm s(-1)). Hyperthermia had no influence on nBack test performance (mean difference from normothermia to hyperthermia, -1 ± 11%; P = 0.276) or, counter to the hypothesis, the increase in MCAV(mean) during nBack testing (mean difference from normothermia to hyperthermia: 0 ± 16 cm s(-1); P = 0.608). These findings indicate that the capacity to increase cerebral perfusion during cognitive activation is unaffected by hyperthermia.
本研究旨在验证高温是否会减弱认知激活过程中脑灌注的增加这一假设。大脑中动脉平均血流速度（MCAVmean）作为脑灌注的指标，而 nBack 测试（一种工作记忆测试）则作为认知任务。高温的特点是皮肤温度（升高 5.0±0.8°C）和肠道温度（升高 1.3±0.1°C）升高（P＜0.001），平均动脉压（降低 11±10mmHg）、呼气末二氧化碳分压（降低 3±6mmHg）和 MCAVmean（降低 10±9cm/s）降低（P＜0.020）。高温对 nBack 测试表现没有影响（与正常体温相比，高温下的平均差异为-1±11%；P=0.276），也与假设相反，高温时 nBack 测试期间 MCAVmean 的增加（与正常体温相比，高温下的平均差异为 0±16cm/s；P=0.608）没有影响。这些发现表明，在认知激活期间增加脑灌注的能力不受高温的影响。
