OUTCOME OF EXTRACELLULAR VOLUME CHANGE--THE OLDEST OLD

老年人患有钠和水平衡失调症的发病率增加。 这是继发于调节细胞外液体积和组成的潜在生理稳态机制中的许多年龄和疾病相关的改变。 为了研究细胞外体积增加对身体功能和激素调节指标的影响，我们正在研究年龄在18至30岁和70岁及以上的健康年轻和老年志愿者。 在进食受控的正常钠饮食三天后，每个志愿者经历24小时的四小时血液采样用于心房利钠肽（ANP）水平，两个连续的12小时尿液收集，和运动试验，在此期间获得ANP、血管加压素、去甲肾上腺素水平和肺毛细血管楔压的非侵入性估计。 大约一个月后，在志愿者食用250 mEq（高）钠饮食三天后重复该研究。 数据分析将阐明当盐摄入量从正常到高变化时，青年和老年久坐志愿者的内分泌、心血管和肾脏系统之间的关系。 还将检查年龄组之间ANP分泌和钠排泄的昼夜变化。

The elderly suffer an increased prevalence of morbid disorders of sodium and water balance. This is secondary to many age and disease related alterations in the underlying physiologic homeostatic mechanisms regulating extracellular fluid volume and composition. To examine the influence of increased extracellular volume on physical functioning and hormonal regulatory indices, we are studying healthy young and old volunteers ranging in age from 18 to 30 years and 70 years and older. After eating a controlled normal sodium diet for three days, each volunteer undergoes 24 hours of four-hourly blood sampling for atrial natriuretic peptide level (ANP), two consecutive 12-hour urine collections, and an exercise test, during which ANP, vasopressin, norepinephrine levels and non-invasive estimation of pulmonary capillary wedge pressures are obtained. The study is repeated approximately a month later after the volunteer has consumed a 250 mEq (high) sodium diet for three days. Data analysis will elucidate the relationship among the endocrine, cardiovascular and renal systems of young and old sedentary volunteers when salt intake is varied from normal to high. Diurnal variation of ANP secretion and sodium excretion between age groups will also be examined.