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

为了检测青春期前男孩和老年男性的热损失效应功能，对他们在一系列六个实验中的冷热反应与年轻男性的反应进行了比较。(1)在适度运动和高温暴露的实验中，青春期前的男孩可以像年轻男性一样有效地调节体温，因为他们的躯干上有更大的血管扩张，尽管出汗较少。此外，在气温较高(高于皮肤温度)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率(CVC_lt；max&gt；)高于年轻男子的结果(局部加热试验)，男孩的主动血管扩张可能部分受到皮肤血管结构成熟相关的改变的影响。(2)在寒冷的环境中，男孩四肢的皮肤温度低于年轻男性。男童不同…状态下肢体温度变化的机制更多的部位：1)手指上更大的血管收缩和更大的表面积/质量比(Ad/质量)，以及2)大腿上更大的Ad/质量和更多的身体脂肪(不是由于血管收缩)。与成熟相关的血管收缩调节的地区差异不受皮肤上冷点数量的影响，因为男孩和年轻男性有相似的冷点。(3)与年轻男性相比，在高温暴露期间，老年男性背部和大腿的血管扩张程度较低，尽管两组人的额部、胸部和手指的血管扩张程度相似。年轻男性和老年男性大腿和背部(局部加热)的CVC_&lt；max&gt；相似，尽管老年男性的前臂CVC_&lt；max&gt；较低。因此，我们认为热应激引起的背部和大腿的低血管扩张是由于年龄相关的血管收缩和血管扩张系统的改变，而不是皮肤血管系统本身的改变。(4)冷暴露时，老年男性的背部和大腿血管收缩较弱，而前额、胸部和手指血管收缩较弱，提示衰老导致血管收缩迟钝，不仅对热应激，而且对冷应激的血管收缩功能随年龄的降低存在地区差异。(5)上述舒血管和收缩反应分别与男生的VO_2和VO_2、VO_2和VO_2、VO_2和VO_2呈正相关。结论是，锻炼习惯可能是改善男孩和老年男性血管舒缩功能的一种手段。较少

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