Biological significance of maturation-and aging-related changes in environmental adaptability

本研究从全身协调的角度探讨了环境适应性随成熟和衰老的变化方式。我们的横断面和纵向（10年）研究结果表明，年龄相关的热损失效应功能下降可能与皮肤血管舒张、每个腺体的排汗量和活跃汗腺密度有关。连续的递减可以从下肢到上半身的背部，上半身的前部，然后上肢，最后到头部。从热和乙酰胆碱诱导（包括轴突反射）出汗试验和皮肤热敏试验的结果来看，我们还发现，与年龄相关的热调节机制的减弱可能涉及皮肤热敏、汗腺胆碱能敏感性以及中枢性伏压运动神经和交感神经的活动。在被动加热和膝关节伸展运动中，更多的血流量和其他测量结果表明，与年龄相关的外周循环（皮肤血流量）的减少可能先于中央循环（动脉血流量）。我们在高温条件下进行等长握持（IH）运动的数据表明，非热热损失响应随老化而下降，其下降程度可能与热热损失响应的下降顺序相似。夏季体育运动时的汗液和直肠温度数据表明，青春期前男孩的汗液功能不发达。热应激期间的数据（空气温度（T_a）在60 min内从28℃线性增加到40℃）表明，与年轻男性相比，青春期前男孩在T_a超过平均皮肤温度引起的热应激下表现出更大的生理和感知应变，这很可能是由于蒸发热损失较小（SR较低）和热增益较大（表面积质量比较大）的共同作用。我们在IH运动中的数据表明，青春期前男孩的非热损失反应不发达（特别是出汗而不是皮肤血管舒张），这种不发达的反应可能与成熟过程中热损失反应的顺序相似。少

This research project addressed the ways in which environmental adaptability change with maturation and aging from the viewpoint of whole body coordination. Our cross-sectional and longitudinal (for 10 yrs) findings suggest that age-related decrement in heat loss effector function may involve cutaneous vasodilation, sweat output per gland, and active sweat gland density in that order. The successive decrement may proceed from the lower limbs to the back of the upper body, the front of the upper body, then the upper limbs and finally to the head. From results of heat-and acetylcholine-induced (including axon reflex) sweating tests, and skin thermal sensitivity test in the same older and younger men, we also discovered that the age-related decrement of thermoregulatory mechanisms may involve the skin thermal sensitivity, the cholinergic sensitivity of sweat glands, and the activities of the central sudomotor and sympathetic nerves in that order. Furthermore, our results of femoral artery … More blood flow and other measurements during passive heating and knee extension exercise suggest that the age-related decrement in the peripheral circulation (skin blood flow) may precede that in the central circulation (artery blood flow). Our data during isometric handgrip (IH) exercise in hot condition suggest that non-thermal heat loss responses decline with aging and the declines may be similar to those of thermal heat loss responses in the order of aging process.The data of sweating and rectal temperature during sports activity in summer suggested that prepubertal boys have an underdeveloped sweating function. The data during the heat stress (air temperature (T_a) was linearly increased from 28℃ to 40℃ over 60 min) suggested that compared with young men, prepubertal boys manifest greater physiological and perceptual strain under heat stress induced by T_a exceeding mean skin temperature, which is most probably attributable to a combination of lower evaporative heat loss, as evidenced by lower SR, and greater heat gain owing to a larger surface area-to-mass ratio. Our data during IH exercise suggest that prepubertal boys have underdeveloped non-thermal heat loss responses (remarkably in sweating rather than cutaneous vasodilation) and the underdeveloped responses may be similar to those of thermal heat loss responses in the order of maturation process. Less