Reed H L, Brice D, Shakir K M, Burman K D, D'Alesandro M M, O'Brian J T
Department of Environmental Medicine, Naval Medical Research Institute, Bethesda, Maryland 20814-5055.
J Appl Physiol (1985). 1990 Oct;69(4):1467-72. doi: 10.1152/jappl.1990.69.4.1467.
We investigated the effects of Antarctic residence (AR) on serum thyroid hormone and cardiovascular responses to a 60-min standard cold air (0 degree C) test (SCAT). Serum total thyroxine (TT4) and serum total triiodothyronine (TT3), free T4 (FT4) and T3 (FT3), thyrotropin (TSH), and percent free fraction of T4 (%FT4) and T3 (%FT3) were measured in normal men (n = 15) before and after each of three SCATs. The SCAT was first carried out in California and then repeated after 24 and 44 wk AR. Mean arterial pressure (MAP) and sublingual oral temperature (Tor) were measured before and during each SCAT. The SCAT did not alter thyroid hormones before or after AR. The %FT4 decreased from 0.0334 +/- 0.0017 to 0.0295 +/- 0.0007% (P less than 0.002) with 44 wk AR but without a significant change in TT4 or FT4 for the same period. The %FT3 also decreased from 0.2812 +/- 0.0128 to 0.2458 +/- 0.0067% (P less than 0.005) after 44 wk AR. FT3 decreased (P less than 0.003) but TT3 and TSH were unchanged with 44 wk AR. The decrease in %FT4 and %FT3 may be theoretically accounted for by a 10% increase in either the capacity or the affinity of the serum binding proteins. The SCAT in California increased MAP and did not change Tor. After 44 wk AR, the SCAT no longer increased MAP but did lower Tor. The shift in the Tor and MAP response to the SCAT is consistent with the associated occurrence of cold adaptation during AR. We describe for the first time a decrease in the free fraction of both serum T3 and T4 present with extended polar residence and independent of a SCAT, further characterizing the recently reported "polar T3 syndrome."
我们研究了南极居住（AR）对血清甲状腺激素以及对60分钟标准冷空气（0摄氏度）测试（SCAT）的心血管反应的影响。在15名正常男性中，在三次SCAT中的每次测试前后测量血清总甲状腺素（TT4）、血清总三碘甲状腺原氨酸（TT3）、游离T4（FT4）和T3（FT3）、促甲状腺激素（TSH）以及T4的游离部分百分比（%FT4）和T3的游离部分百分比（%FT3）。SCAT首先在加利福尼亚进行，然后在AR 24周和44周后重复进行。在每次SCAT之前和期间测量平均动脉压（MAP）和舌下口腔温度（Tor）。SCAT在AR前后均未改变甲状腺激素。随着44周的AR，%FT4从0.0334±0.0017降至0.0295±0.0007%（P<0.002），但同期TT4或FT4无显著变化。44周的AR后，%FT3也从0.2812±0.0128降至0.2458±0.0067%（P<0.005）。随着44周的AR，FT3降低（P<0.003），但TT3和TSH未改变。%FT4和%FT3的降低理论上可能是由于血清结合蛋白的容量或亲和力增加10%所致。在加利福尼亚进行的SCAT使MAP升高且未改变Tor。44周的AR后，SCAT不再使MAP升高，但确实降低了Tor。Tor和MAP对SCAT反应的变化与AR期间冷适应的相关发生一致。我们首次描述了长期极地居住时血清T3和T4的游离部分均降低，且与SCAT无关，进一步描述了最近报道的“极地T3综合征”。
