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

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。目的：量化VC期间核心-皮肤热阻与年龄和瘦体重的关系，并完善寒冷环境下人体传热模型。假设a.热平衡方程的解将产生较低的导出核心对皮肤的热阻（组织绝缘，IT），与年轻的受试者相比，具有相似的尺寸和身体成分。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。年龄组包括正常和瘦/肌肉减少的个体。年轻受试者定义为18-30岁；年龄较大的受试者为65-85岁。受试者使用仪器测量身体核心和皮肤温度、前臂血流量（FBF）、皮肤血流量（SkBF）、血压和心率。每隔20分钟收集最后5分钟的过期空气，分析其体积、O2浓度和CO2浓度。在干球温度(Tdb) = 23℃（73.4华氏度）和相对湿度(RH) = 30%的条件下，经过20分钟的基准期后，Tdb降至12℃（53.6华氏度）并保持40分钟。然后，以每20分钟1摄氏度（1.8华氏度）的速度降低Tdb，直到开始发抖或受试者希望停止。颤抖是由视觉观察和自我报告决定的。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.