AGE AND CONTROL OF SKIN BLOOD FLOW: AGE AND LEAN BODY MASS

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。目的：量化VC过程中核心到皮肤的热阻作为年龄和瘦体重的函数，并完善寒冷环境中人体热传递的模型。假设a.热平衡方程的解将产生较低的衍生核心到皮肤的热阻（组织绝缘，IT）相比，年轻的受试者相似的大小和身体组成。假设B。控制年龄，体重减少和/或瘦体重减少的受试者将表现出较低的最大IT。瘦组由正常和瘦/肌肉减少的个体组成。年轻受试者定义为18-30岁;老年受试者定义为65-85岁。受试者被装备用于测量身体的核心和皮肤温度、前臂血流量（FBF）、皮肤血流量（SkBF）、血压和心率。在每20分钟时间段的最后5分钟收集呼出的空气，并分析体积、O2浓度和CO2浓度。在干球空气温度（Tdb）= 23 ℃（73.4 ℉）和相对湿度（RH）= 30%的20分钟基线期后，Tdb降至12 ℃（53.6 ℉）并保持40分钟。然后，Tdb以1摄氏度（1.8华氏度）/20分钟的速率降低，直到寒战发作或受试者希望停止。通过目视观察和自我报告确定颤抖。在30分钟的恢复过程中，激光多普勒探头周围的区域被加热。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Purpose: To quantify core-to-skin thermal resistance during VC as a function of age and lean body mass, and refine models of human heat transfer in cold environments. Hypothesis a. The solution of heat balance equations will yield a lower derived core-to-skin thermal resistance (tissue insulation, IT) for older compared to young subjects of similar size and body composition. Hypothesis b. Controlling for age, subjects with decreased body mass and/or decreased lean body mass will exhibit a lower maximal IT. Age-groups consist of normal and lean/sarcopenic individuals. Young subjects are defined as 18-30 years; older subjects are 65-85 years old. Subjects are instrumented for measurement of the body's core and skin temperatures, forearm blood flow (FBF), skin blood flow (SkBF), blood pressure, and heart rate. Expired air is collected for the last 5 min of every 20 min period and analyzed for volume, O2 concentration, and CO2 concentration. After a 20-min baseline period at a dry bulb air temperature (Tdb) = 23 oC (73.4 degrees F) and relative humidity (RH) = 30%], Tdb are decreased to 12 degrees C (53.6 oF) and maintained for 40 minutes. Then, Tdb is lowered at a rate of 1degree C (1.8 degrees F)/20 min, until the onset of shivering or the subject wishes to discontinue. Shivering is determined by visual observation and self-report. During a 30-min recovery, the area around the laser Doppler probes is heated.