仿自然风对模拟失重体温调节反应的影响

Effects of Simulated Natural Air Flow on Thermoregulatory Response during Simulated Microgravity

航天飞行和模拟失重可抑制人体热调节反应,主要表现为机体静息和运动状态下皮肤血管舒张反应能力下降和核心体温的升高。载人航天器内采用恒速机械风(CAF)保持舱内大气环境的均匀,地面研究发现仿自然风(SNAF)可较CAF显著加强机体的冷感觉。为探讨SNAF是否可以较CAF一定程度上缓解失重状态导致的体温调节能力下降,以30天-6°头低位卧床模拟微重力的生理效应,7名男性被试者分别在卧床前和卧床第29天,暴露于对照无风、CAF和SNAF气流模式下,周围环境温度为23℃,后两种气流模式的平均风速为0.2 m/s。记录实验中被试者的直肠温度(Tre)、皮肤温度和皮肤血管传导率(CVC)及其热感觉(TSV)。经过卧床,对照环境Tre显著升高;卧床后,与CAF相比,SNAF下的Tre的降低程度更多,且更接近对照水平;平均皮肤温度、CVC和TSV均显著降低。卧床后SNAF下的TSV接近"热中性"。实验结果表明,与恒速通风相比,仿自然通风可更为有效地维持卧床状态下的核心体温。

Spaceflight and simulated microgravity may impair thermoregulatory responses of the hu-man body and the two main reactions include higher core temperature and attenuated thermoregulato-ry cutaneous vasodilation, under the condition of rest or exercise.Though constant air flow ( CAF) is used to keep the balance of the atmosphere inside the manned spacecraft, natural air flow or simu-lated natural air flow ( SNAF) has been found to enhance the body’ s cold sensation significantly in comparison with CAF on Earth.On the basis of the physiological effect caused by simulated micro-gravity conditions where seven healthy males underwent 30 days of -6 °head-down bed rest ( HD-BR) , this study intends to explore whether SNAF can ameliorate impaired thermoregulatory function to a greater extent than CAF.Immediately before the bed rest( pre-HDBR) and on day 29 of HDBR ( HDBR 29 ) , the subjects were exposed to three air flow patterns at 23℃: a still air flow control ( CON) , CAF, and SNAF.The mean air velocity of the latter two patterns was 0.2 m/s.The rectal temperature (Tre), skin temperature (Tsk), cutaneous vascular conductance (CVC) and thermal sensation vote ( TSV) of each subject were also measured during the sessions.Tre was significantly elevated after 29 days of HDBR and decreased to a greater extent in SNAF than in CAF on HD-BR29.However, there was no significant difference between Tre in SNAF on HDBR29 and that in CON on pre-HDBR.Mean Tsk , CVC, and TSV in SNAF were also significantly lower than those in CAF on HDBR29.Moreover, TSV was close to ‘thermoneutral’ under SNAF on HDBR 29.These data indicate that simulated natural air flow might be more effective than constant air movement at preserving core temperature at a thermoneutral ambient temperature during HDBR.