Schlader Zachary J, Coleman Gregory L, Sackett James R, Sarker Suman, Chapman Christopher L, Johnson Blair D
Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, USA.
Exp Physiol. 2016 Sep 1;101(9):1218-1229. doi: 10.1113/EP085837. Epub 2016 Aug 2.
What is the central question of this study? Do increases in metabolic heat production and sweat rate precede the initiation of thermoregulatory behaviour in resting humans exposed to cool and warm environments? What is the main finding and its importance? Thermoregulatory behaviour at rest in cool and warm environments is preceded by changes in vasomotor tone in glabrous and non-glabrous skin, but not by acute increases in metabolic heat production or sweat rate. These findings suggest that sweating and shivering are not obligatory for thermal behaviour to be initiated in humans. We tested the hypothesis that acute increases in metabolic heat production and sweating precede the initiation of thermoregulatory behaviour in resting humans exposed to cool and warm environments. Twelve healthy young subjects passively moved between 17 and 40°C rooms when they felt 'too cool' (C→W) or 'too warm' (W→C). Skin and internal (intestinal) temperatures, metabolic heat production, local sweat rate (forearm and chest) and cutaneous vascular conductance (CVC; forearm and fingertip) were measured continually. Compared with pretest baseline (31.8 ± 0.3°C), skin temperature was higher at C→W (32.0 ± 0.7°C; P = 0.01) and W→C (34.5 ± 0.5°C; P < 0.01). Internal temperature did not differ (P = 0.12) between baseline (37.2 ± 0.3°C), C→W (37.2 ± 0.3°C) and W→C (37.0 ± 0.3°C). Metabolic heat production was not different from baseline (40 ± 9 W m ) at C→W (39 ± 7 W m ; P = 0.50). Forearm (0.06 ± 0.01 mg cm min ) and chest (0.04 ± 0.02 mg cm min ) sweat rate at W→C did not differ from baseline (forearm, 0.05 ± 0.02 mg cm min and chest, 0.04 ± 0.02 mg cm min ; P ≥ 0.23). Forearm CVC was not different from baseline (0.30 ± 0.21 perfusion units (PU) mmHg ) at C→W (0.24 ± 0.11 PU mmHg ; P = 0.17), but was higher at W→C (0.65 ± 0.33 PU mmHg ; P < 0.01). Fingertip CVC was different from baseline (2.6 ± 2.0 PU mmHg ) at C→W (0.70 ± 0.42 PU mmHg ; P < 0.01) and W→C (4.49 ± 1.66 PU mmHg ; P < 0.01). Thermoregulatory behaviour at rest in cool and warm environments is preceded by changes in vasomotor tone in glabrous and non-glabrous skin, but not by acute increases in metabolic heat production or sweat rate.
本研究的核心问题是什么？在处于凉爽和温暖环境中的静息人体中，代谢产热和出汗率的增加是否先于体温调节行为的启动？主要发现及其重要性是什么？在凉爽和温暖环境中静息时的体温调节行为之前，无毛和有毛皮肤的血管舒缩张力会发生变化，但代谢产热或出汗率不会急剧增加。这些发现表明，出汗和颤抖并非人体启动体温调节行为的必要条件。我们检验了这样一个假设：在处于凉爽和温暖环境中的静息人体中，代谢产热和出汗的急剧增加先于体温调节行为的启动。12名健康的年轻受试者在感觉“太冷”（C→W）或“太热”（W→C）时，在17至40°C的房间之间被动移动。持续测量皮肤和内部（肠道）温度、代谢产热、局部出汗率（前臂和胸部）以及皮肤血管传导率（CVC；前臂和指尖）。与测试前基线（31.8±0.3°C）相比，C→W时皮肤温度较高（32.0±0.7°C；P = 0.01），W→C时皮肤温度也较高（34.5±0.5°C；P < 0.01）。基线（37.2±0.3°C）、C→W（37.2±0.3°C）和W→C（37.0±0.3°C）之间的内部温度无差异（P = 0.12）。C→W时的代谢产热与基线（40±9 W m）无差异（39±7 W m；P = 0.50）。W→C时前臂（0.06±0.01 mg cm min）和胸部（0.04±0.02 mg cm min）的出汗率与基线（前臂，0.05±0.02 mg cm min和胸部，0.04±0.02 mg cm min；P≥0.23）无差异。C→W时前臂CVC与基线（0.30±0.21灌注单位（PU） mmHg）无差异（0.24±0.11 PU mmHg；P = 0.17），但W→C时较高（0.65±0.33 PU mmHg；P < 0.01）。C→W时指尖CVC与基线（2.6±2.0 PU mmHg）不同（0.70±0.42 PU mmHg；P < 0.01），W→C时也不同（4.49±⒈66 PU mmHg；P < 0.01）。在凉爽和温暖环境中静息时的体温调节行为之前，无毛和有毛皮肤的血管舒缩张力会发生变化，但代谢产热或出汗率不会急剧增加。
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