Renal stone risk in a simulated microgravity environment: Impact of treadmill exercise with lower body negative pressure
Renal stone risk in a simulated microgravity environment: Impact of treadmill exercise with lower body negative pressure
复制标题
DOI：
10.1016/s0022-5347(06)00572-6
复制
发表时间：
2006-07-01
影响因子：
6.6
通讯作者：
Hargens, Alan
中科院分区：
文献类型：
--
作者：
Monga, Manoj;Macias, Brandon;Hargens, Alan
目的：航天期间长期暴露于微重力会引起代谢变化，从而增加肾结石形成的风险。在双子座、阿波罗、天空实验室和航天飞机任务期间的研究表明，肾功能、液体动态平衡和骨吸收发生变化，导致尿草酸钙、刷石、尿酸钠和尿酸过饱和度增加。随着航天任务持续时间的增加，研究增加尿液过饱和度的对策是一个重要的优先事项。材料和方法：共有11对同卵双胞胎保持6度头朝下，倾斜床上休息30天，以模拟延长的微重力。每对随机选择一对双胞胎，在下体负压室中仰卧锻炼，每周6天，持续40分钟，然后在50 mm Hg的下体负压下休息5分钟。另一对双胞胎作为非运动对照组。运动下半身负压室压力(52~63 mm。HG)被调整为产生相当于在1.0至1.2倍体重的地球上直立跑步时的向下力量。在标准饮食(包括170mEq钠、1,000 mg钙、0.8g/kg动物蛋白和2,500千卡)5天后，在其他地方进行卧床前尿结石风险分析，然后在卧床休息和恢复阶段进行监测。结果：非运动对照组仅卧床休息1周后尿钙显著增加(p=0.001)。然而，在运动组中没有注意到这种增加。各组卧床时刷石过饱和度显著增加，尽管非运动对照组的增加显著高于运动组(p=0.006)。运动组卧床时草酸钙过饱和度增加(p=0.004)。卧床第2周和第3周，非运动对照组平均尿量SD分别为2.01±-0.21vs1.63+/-0.18vs2.03+/-0.22vs1.81+/-0.20，差异有统计学意义(P=0.055)。非运动对照组第1周和第3周的尿液pH值显著高于运动组(分别为6.62+/-0.7vs6.49+/-0.5和6.58+/-0.6vs6.49+/-0.8，P=0.01)。结论：卧床休息显著改变了尿路环境，有利于结石的形成。下半身负压室跑步机运动提供了一些保护，防止模拟微重力下结石风险的增加，特别是在高钙尿和刷石结石形成的风险方面。利用下体负压来加强太空有氧运动，可能会降低宇航员结石形成的风险。应考虑采取辅助措施，包括积极的水化和碱化治疗。
Purpose: Prolonged exposure to microgravity during spaceflight causes metabolic changes that increase the risk of renal stone formation. Studies during the Gemini, Apollo, Skylab and Shuttle missions demonstrated alterations in renal function, fluid homeostasis and bone resorption that result in increased urinary supersaturation of calcium oxalate, brushite, sodium urate and uric acid. Developing countermeasures to increased urinary supersaturation is an important priority as the duration of space missions increases.Materials and Methods: A total of 11 sets of identical twins remained on 6-degree head down, tilt bed rest for 30 days to simulate prolonged microgravity. One twin per pair was randomly selected to exercise while supine in a lower body negative pressure chamber 6 days weekly for 40 minutes, followed by 5 minutes of resting lower body negative pressure at 50 mm Hg. The other twin served as a nonexercise control. Pressure in the exercise lower body negative pressure chamber (52 to 63 mm. Hg) was adjusted to produce footward forces equivalent to those for upright running on Earth at 1.0 to 1.2 X body weight. Pre-bed rest urinary stone risk profiles were done elsewhere after 5 days of a standardized diet, consisting of 170 mEq sodium, 1,000 mg calcium, 0.8 gm/kg animal protein and 2,500 kcal, and then throughout the bed rest and recovery phases of the protocol.Results: A significant increase in urinary calcium after just 1 week of bed rest was noted in the nonexercise control group (p = 0.001). However, no such increase was noted in the exercise group. Brushite supersaturation increased significantly from bed rest in each group, although the increase was significantly higher in the nonexercise control group than in the exercise group (p = 0.006). Calcium oxalate supersaturation increased during bed rest in the exercise group (p = 0.004). It trended toward a higher level in the nonexercise control group, although this did not achieve significance (p = 0.055) Mean urine volume SD was significantly higher in the nonexercise control group than in the exercise group at bed rest week 2 and at week 3 (2.01 +/- 0.21 vs 1.63 +/- 0.18 l and 2.03 +/- 0.22 vs 1.81 +/- 0.20, respectively). Urinary pH was significantly higher in the nonexercise control group than in the exercise group at week 1 and week 3 (6.62 +/- 0.7 vs 6.49 +/- 0.5 and 6.58 +/- 0.6 vs 6.49 +/- 0.8, respectively, p = 0.01).Conclusions: Bed rest significantly alters the urinary environment to favor calculous formation. Lower body negative pressure chamber treadmill exercise offers some protection against increases in stone risk during simulated microgravity, particularly with regard to the risks of hypercalciuria and brushite stone formation. The use of lower body negative pressure to augment aerobic exercise in space may decrease the risk of stone formation in astronauts. Adjunct measures, including aggressive hydration and alkalinization therapy, should be considered.