Zhang L N, Gao F, Ma J, Zhang L F
Department of Aerospace Physiology, Fourth Military Medical University, Xi'an, P.R. China.
J Gravit Physiol. 2000 Jul;7(2):P143-4.
Artificial gravity will be considered for long-duration spaceflight missions. Recent studies have shown that continuous exposure to gravity does not appear necessary to prevent the adverse effects of weightlessness, instead intermittent exposure may suffice. Vernikos et al reported that 1 G intermittent exposures with and without walking exercise was effective in preventing physiologic deconditioning with 4-d, -6 degrees bedrest, and standing at 1 G was most effective in preventing orthostatic intolerance. Our previous work has demonstrated differential adaptational changes in structure, function, and innervation state of arterial vasculature in different body regions of rat during simulated weightlessness and further suggested that these changes might be one of the most important mechanisms accounting for postflight orthostatic intolerance. We therefore designed the present study involving a comprehensive evaluation of the effect of intermittent G exposure in preventing the differential functional changes of the arteries at the end of 3-wk head-down tail suspension in rats to answer the following questions: (1) do intermittent G exposure have counteracting effect in preventing differential functional changes in arterial vasculature with tail-suspension? (2) among the treatments used in the present study, i.e., head-up tilt (HUT), standing (STD), and centrifugation (CEN), what kind of exposure is more effective? (3) how much time in daily 1 G exposure is needed to maintain the normal (1 G) vascular responsiveness?
长期太空飞行任务将考虑采用人工重力。最近的研究表明，持续暴露于重力环境对于预防失重的不良影响似乎并非必要，间歇性暴露可能就足够了。韦尔尼科斯等人报告称，在4天、-6度卧床休息期间，进行1G间歇性暴露（无论有无步行锻炼）对于预防生理机能衰退是有效的，而在1G环境下站立对于预防直立不耐受最为有效。我们之前的研究表明，在模拟失重期间，大鼠不同身体部位的动脉血管在结构、功能和神经支配状态方面存在适应性差异变化，并且进一步表明这些变化可能是飞行后直立不耐受的最重要机制之一。因此，我们设计了本研究，全面评估间歇性G暴露对预防大鼠3周头低位尾吊结束时动脉功能差异变化的影响，以回答以下问题：（1）间歇性G暴露对预防尾吊引起的动脉血管功能差异变化是否有抵消作用？（2）在本研究中使用的处理方法，即头高位倾斜（HUT）、站立（STD）和离心（CEN）中，哪种暴露更有效？（3）每天需要进行多长时间的1G暴露才能维持正常（1G）的血管反应性？
