Inoue Y, Shibasaki M
Department of Hygiene, Kobe University School of Medicine, Japan.
Eur J Appl Physiol Occup Physiol. 1996;74(1-2):78-84. doi: 10.1007/BF00376498.
Ten older (aged 64-76 years) and ten younger (aged 20-24 years) healthy men were exposed to a standard heat stress [by placing the lower legs and feet in a water bath at 42 degrees C while sitting in a controlled environment (ambient temperature 35 degrees C and 45% relative humidity) for 60 min]. During passive heating, the rectal temperature of the older men was significantly greater (P < 0.05) and mean skin temperature was lower (P < 0.001), compared to the younger men. Skin blood flow by laser Doppler flowmetry (LDF) was significantly lower on the chest and thigh for the older men (P < 0.001), but forehead LDF did not differ between the groups. The percentages of total LDF in the older men to total LDF in the younger men for the last 30 min were 99%, 58% and 50% on the forehead, chest and thigh, respectively. The age-related differences in LDF responses mirrored cutaneous vascular conductances (CVC), since no group and time effects were observed in mean arterial blood pressure during the test. During the last 30 min the local sweat rates (msw) on the back and thigh were significantly lower for the older men (P < 0.02), but not on forehead, chest and forearm, although the older men had lower msw during the first 30 min exposure regardless of site (P < 0.03). The percentages of total msw in the older men to total msw in the younger men during the last 30 min were 105%, 99%, 63%, 106% and 88% on the forehead, chest, thigh, forearm, and back, respectively. During the latter half of the exposure, the older men had similar LDF, CVC and msw on the forehead, lower LDF and CVC and a similar msw on the chest, and lower LDF, CVC and msw on the thigh, compared to the younger men. These results suggest firstly that regional differences exist in the age-related decrement of cutaneous vasodilatation as well as sweat gland function, secondly that the age-related decrement in cutaneous vascular function may precede a decrement in sweat gland function, and thirdly that the successive decrements may develop sequentially from the lower limbs to the upper body, and head.
十名年龄较大（64 - 76岁）和十名年龄较小（20 - 24岁）的健康男性接受了标准热应激（将小腿和脚部置于42摄氏度的水浴中，同时坐在可控环境中（环境温度35摄氏度，相对湿度45%）60分钟）。在被动加热过程中，与年轻男性相比，老年男性的直肠温度显著更高（P < 0.05），平均皮肤温度更低（P < 0.001）。通过激光多普勒血流仪（LDF）测量，老年男性胸部和大腿的皮肤血流量显著更低（P < 0.001），但两组之间前额的LDF没有差异。在最后30分钟内，老年男性前额、胸部和大腿的LDF占年轻男性总LDF的百分比分别为99%、58%和50%。LDF反应的年龄相关差异反映了皮肤血管传导性（CVC），因为在测试过程中平均动脉血压未观察到组间和时间效应。在最后30分钟内，老年男性背部和大腿的局部出汗率（msw）显著更低（P < 0.02），但前额、胸部和前臂没有差异，尽管在最初30分钟的暴露过程中，无论部位如何，老年男性的msw都更低（P < 0.03）。在最后30分钟内，老年男性前额、胸部、大腿、前臂和背部的msw占年轻男性总msw的百分比分别为105%、99%、63%、106%和88%。在暴露的后半段，与年轻男性相比，老年男性前额的LDF、CVC和msw相似，胸部的LDF和CVC更低但msw相似，大腿的LDF、CVC和msw更低。这些结果表明，首先，皮肤血管舒张以及汗腺功能的年龄相关减退存在区域差异；其次，皮肤血管功能的年龄相关减退可能先于汗腺功能的减退；第三，这些连续的减退可能从下肢向上身和头部依次发展。
