Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism of Maastricht University Medical Center+, the Netherlands.
Acta Physiol (Oxf). 2011 Dec;203(4):419-27. doi: 10.1111/j.1748-1716.2011.02336.x. Epub 2011 Aug 12.
Higher winter mortality in elderly has been associated with augmented systolic blood pressure (SBP) response and with impaired defense of core temperature. Here we investigated whether the augmented SBP upon mild cold exposure remains after a rewarming period, and whether SBP changes are linked to thermoregulation. Therefore, we tested the following hypotheses: cold-induced increase in SBP (1) remains augmented after rewarming in elderly compared to young adults (2) is related to non-shivering thermogenesis (NST) upon mild cold (3) is related to vasoconstriction upon mild cold.
Blood pressure, energy expenditure (EE), skin and core temperature, skin perfusion (abdomen, forearm, both sides of hand) and % body fat were measured in 12 young adults (Y) and 12 elderly (E). Supine subjects were exposed to a thermoneutral baseline 0.5 h (T(air) = 30.1°C), 1 h mild cold (T(air) = 20.7°C), 1 h rewarming (T(air) = 34.8°C) and 1 h baseline (T(air) = 30.5°C).
Upon mild cold only the young adults showed significant NST (Y: +2.5 ± 0.6 W m(-2), P < 0.05). No significant age effects in vasoconstriction were observed. After rewarming per cent change in SBP (%ΔSBP) remained significantly increased in both age groups and was augmented in elderly (Y: +5.0% ± 1.2% vs. E: +14.7% ± 3.1%, P < 0.05). Regression analysis revealed that %ΔSBP significantly related to ΔEE upon mild cold (P < 0.01, r(2) = 0.35) and in elderly also to %body fat (P < 0.02, r(2) = 0.57).
Individual changes in SBP after rewarming correlate negatively to NST. Elderly did not show NST, which explains the greater SBP increase in this group. In elderly a relatively large %body fat protected against the adverse effects of mild cold.
老年人冬季死亡率较高与收缩压（SBP）反应增强以及核心体温保护受损有关。在这里，我们研究了轻度寒冷暴露后 SBP 的增强反应在复温期后是否仍然存在，以及 SBP 的变化是否与体温调节有关。因此，我们检验了以下假设：（1）与年轻人相比，老年人在复温后轻度寒冷引起的 SBP 增加（1）仍然增强；（2）与轻度寒冷时的非颤抖性产热（NST）有关；（3）与轻度寒冷时的血管收缩有关。
12 名年轻成年人（Y）和 12 名老年人（E）的血压、能量消耗（EE）、皮肤和核心温度、皮肤灌注（腹部、前臂、双手两侧）和%体脂进行了测量。仰卧位受试者暴露于 0.5 小时的温热基线（T（空气）= 30.1°C），1 小时轻度寒冷（T（空气）= 20.7°C），1 小时复温（T（空气）= 34.8°C）和 1 小时基线（T（空气）= 30.5°C）。
只有年轻成年人在轻度寒冷时表现出明显的 NST（Y：+2.5 ± 0.6 W m（-2），P < 0.05）。观察到血管收缩无明显年龄效应。复温后，两组 SBP 的百分比变化（%ΔSBP）仍显著增加，且老年人增加（Y：+5.0%±1.2% vs. E：+14.7%±3.1%，P < 0.05）。回归分析表明，%ΔSBP 与轻度寒冷时的ΔEE 显著相关（P < 0.01，r（2）= 0.35），在老年人中也与%体脂相关（P < 0.02，r（2）= 0.57）。
复温后 SBP 的个体变化与 NST 呈负相关。老年人没有表现出 NST，这解释了该组 SBP 增加更大的原因。在老年人中，相对较大的%体脂可防止轻度寒冷的不利影响。
