Kim C S, Maekawa Y, Fujita M, Sato N, Nishimuta M, Ishizaki Y, Ohta F, Fukuoka H
Dept. of Human Science, Waseda Univ., Saitama, Japan.
J Gravit Physiol. 2000 Jul;7(2):P125-6.
Weight bearing and physical activity are important mechanical stimuli to bone growth and metabolism, and microgravity, such a space flight and/or bed rest, induces bone resorption and bone loss. An increased excretion of urinary Ca, an increased bone resorption and a decreased bone mineral density (BMD) have been observed in bed rest experiment of healthy subjects. Bone resorption markers show the specific circadian rhythms in human. Cross-linked carboxyl-terminal telopeptide of type I collagen (ICTP) and the urinary excretion of deoxypyridinoline (Dpy) are the highest in the early morning and the lowest late at night. Bed rest immobilization might influence these rhythms, due to no mechanical loading with loss of daily life activity. Bone resorption markers in healthy subjects had been compared between before and during bed rest to determine disruption of diurnal rhythms of bone resorption.
负重和体育活动是对骨骼生长和代谢重要的机械刺激因素，而微重力，如太空飞行和/或卧床休息，会引发骨质吸收和骨质流失。在健康受试者的卧床休息实验中，观察到尿钙排泄增加、骨质吸收增加以及骨矿物质密度（BMD）降低。骨吸收标志物在人体中呈现特定的昼夜节律。I型胶原交联羧基末端肽（ICTP）和脱氧吡啶啉（Dpy）的尿排泄量在清晨最高，深夜最低。卧床制动可能会影响这些节律，因为缺乏机械负荷且丧失了日常生活活动。为了确定骨吸收昼夜节律的紊乱情况，对健康受试者卧床休息前后的骨吸收标志物进行了比较。
