Budd G M, Brotherhood J R, Thomas D W, Beasley F A, Hendrie A L, Jeffery S E, Lincoln G J, Solaga A T
National Institute of Occupational Health and Safety, Sydney NSW, Australia.
Eur J Appl Physiol Occup Physiol. 1993;67(5):450-6. doi: 10.1007/BF00376462.
The purpose of this study was to see whether artificial acclimatization to cold would reduce the pressor response to noradrenaline (NA) as natural acclimatization has been shown to do, and whether it would induce nonshivering thermogenesis. Three white men were infused with NA at four dosage levels between 0.038 and 0.300 microgram.kg-1.min-1 (2-23 micrograms.min-1), before and after artificial acclimatization to cold and again 4 months later when acclimatization had decayed. Acclimatization was induced by ten daily cold (15 degrees C) baths of 30-60 min followed by rapid rewarming in hot (38-42 degrees C) water, and was confirmed by tests of the subjects' responses to whole-body cooling in air. Three control subjects also underwent the first and third tests. Acclimatization substantially reduced the pressor response to NA at 0.150 and 0.300 micrograms.kg-1.min-1, confirming earlier findings by the same technique in naturally acclimatized men, and its decay increased this response to beyond its initial levels (P < 0.05 for both changes). Acclimatization did not change the response to NA of heart rate, subjective impressions, skin temperature of finger and toe, pulmonary ventilation, or plasma free fatty acids and ketone bodies. At no time did NA increase oxygen consumption, or increase skin temperature or heat flow over reported sites of brown fat. These findings would seem to show that acclimatization to cold reduces sensitivity to the pressor effect of NA but does not induce nonshivering thermogenesis, and that the reduced sensitivity is replaced by a hypersensitivity to NA when acclimatization decays.
本研究的目的是观察人工冷适应是否会像自然冷适应那样降低对去甲肾上腺素（NA）的升压反应，以及人工冷适应是否会诱导非寒战产热。三名白人男性在人工冷适应前后以及4个月后适应消退时，分别以0.038至0.300微克·千克⁻¹·分钟⁻¹（2至23微克·分钟⁻¹）的四个剂量水平输注NA。通过每天10次30 - 60分钟的15摄氏度冷水浴，随后在38 - 42摄氏度热水中快速复温来诱导适应，并通过测试受试者对空气中全身冷却的反应来确认。三名对照受试者也接受了第一次和第三次测试。冷适应显著降低了在0.150和0.300微克·千克⁻¹·分钟⁻¹剂量下对NA的升压反应，这与之前用相同技术在自然冷适应男性中得到的结果一致，并且适应消退后该反应增加到超过初始水平（两种变化均P < 0.05）。冷适应并未改变心率、主观感受、手指和脚趾皮肤温度、肺通气或血浆游离脂肪酸和酮体对NA的反应。NA在任何时候都没有增加氧气消耗，也没有增加棕色脂肪报道部位的皮肤温度或热流。这些发现似乎表明，冷适应降低了对NA升压作用的敏感性，但不会诱导非寒战产热，并且当适应消退时，降低的敏感性会被对NA的超敏反应所取代。
