Regional differences in maturation-and age-related changes of heat loss effector function in relation to exercise habits.

为了研究青春期前男孩和老年男性的热损失效应器功能，在一系列的六个实验中，他们的热和冷反应与年轻男性的反应进行了比较。(1)在适度运动和热暴露的实验中，青春期前的男孩可以通过躯干更大的血管舒张来有效地调节体温，尽管出汗较少。此外，在空气温度（高于皮肤温度）较高的情况下，与年轻男子相比，男孩的血管扩张和头部出汗迅速增加。根据男孩背部和大腿的最大皮肤血管传导性（CVC_<max>）高于年轻男性（通过局部加热试验）的结果，男孩的主动血管舒张可能部分受到皮肤血管结构中与成熟相关的改变的影响。(2)与年轻男性相比，在寒冷环境中，男孩四肢的皮肤温度较低。男孩下肢温度的机制不同 ...更多信息 按研究中心：1）手指上更大的血管收缩和更大的表面积与质量比（Ad/质量），以及2）大腿上更大的Ad/质量和更大的身体脂肪（不是由于血管收缩）。与成熟相关的血管收缩变化的区域差异不受皮肤上冷点数量的影响，因为男孩与年轻男子有相似的冷点。(3)与年轻男性相比，老年男性在热暴露期间背部和大腿的血管舒张较低，尽管两组之间前额，胸部和手指的血管舒张相似。年轻<max>人和老年人的大腿和背部（通过局部加热）的CVC_相似，尽管老年人的前臂CVC<max>_较低。因此，热应激时背部和大腿血管舒张功能的降低是由于血管收缩和舒张系统的增龄性改变，而不是皮肤血管系统本身的改变。(4)此外，在冷暴露期间，老年男性在背部和大腿上显示出较低的血管收缩，但在前额，胸部和手指上没有，这表明衰老导致钝性血管收缩，并且区域差异存在于与年龄相关的血管收缩功能的衰减中，不仅热应激，而且冷应激。(5)上述血管舒张反应和血管收缩反应在男孩中分别与VO_2密切相关，在老年男性<2max>中分别与计步器读数和VO_2密切相关<2max>。结论是，运动习惯可能是改善男孩和老年男性血管功能的一种手段。少

To examine heat loss effector function of prepubertal boys and older men, their heat and cold responses during a series of six experiments were compared with the responses of young men. (1) During both experiments of moderate exercise and heat exposure, prepubertal boys could thermoregulate as efficiently as young men by greater vasodilation on their trunk despite lower sweating. Furthermore, in the case of higher air temperature (than skin temperature), boys showed a rapid increment of vasodilation and sweating on the head, compared to young men. Based on the results that boys had higher maximal cutaneous vascular conductance (CVC_<max>) on the back and thigh compared to young men (by local heating test), the active vasodilation of boys may be affected partially by maturation-related modification in the structure of cutaneous vasculature. (2) In cold exposures boys showed lower skin temperatures on limbs, compared to young men. The mechanism of lower limb temperatures in boys differed … More by sites : 1) greater vasoconstriction and larger surface area-to-mass ratio (Ad/mass) on the finger, and 2) larger Ad/mass and greater body fatness (not due to vasoconstriction) on the thigh. Regional differences in maturation-related modification of vasoconstriction were not affected by the number of cold spots on skin, since boys had similar cold spots with young men. (3) Compared to young men, older men had lower vasodilation on the back and thigh during heat exposure, although vasodilation was similar between both groups on the forehead, chest, and finger. CVC_<max> on thigh and back (by local heating) was similar between young and older men, although forearm CVC_<max> was lower in older men. Therefore it was suggested that the lower vasodilation on the back and thigh to heat stress was due to age-related modification of vasoconstrictor and vasodilator system rather than to the change of cutaneous vasculature itself. (4) Furthermore, during cold exposure older men showed lower vasoconstriction on the back and thigh, but not on the forehead, chest and finger, suggesting that aging leads to blunt vasoconstriction, and regional differences exist in the age-related decrements of vasomotor function to not only heat but also cold stress. (5) Vasodilative and vasoconstrictive responses mentioned above were closely related to VO_<2max> in boys and both factors of pedometer readings and VO_<2max> in older men, respectively. It was concluded that exercise habits could be a means to improve vasomotor function in both boys and older men. Less