Wei C N, Tanaka T, Yonemitsu H, Ueda A
Kumamoto Kinoh Hospital, Japan. Kumamoto University School of Medicine, Japan.
Jpn J Physiol. 1998 Feb;48(1):33-7. doi: 10.2170/jjphysiol.48.33.
Osteoporosis due to mineral loss is a major health problem resulting from long-term spaceflight. The development of a suitable countermeasure is essential because an advanced decrease in bone density could be irreversible. Therefore the current study was performed to test our hypothesis that the loading of bones by electrical stimulation-induced muscle contraction may prevent the mineral loss caused by gravitational unloading and bone growth will be maintained. During 10 d of hindlimb suspension, electrical stimulation at 1, 50, or 100 Hz was administered through the left sciatic nerve at the gluteal region of rats with approximately 300 g body weight. The dry weight, mineral content, and mineral density in hindlimb bones were analyzed. The dry weight and mineral content of femur and tibia-fibula in hindlimb-suspended rats tended to be less than in the age-matched cage controls. However, these detrimental effects were prevented by stimulation at 50 and 100 Hz. A positive effect of stimulation was seen even in the nonstimulated limb, although greater effect was induced in the stimulated limb. It is suggested that loading by stimulation-induced muscle contraction at higher frequencies is beneficial for the maintenance of bone growth or the prevention of mineral loss, or both, during hindlimb suspension in rats.
因矿物质流失导致的骨质疏松是长期太空飞行引发的一个主要健康问题。研发合适的应对措施至关重要，因为骨密度的大幅下降可能是不可逆的。因此，开展了本研究以验证我们的假设，即通过电刺激诱导肌肉收缩对骨骼施加负荷可能预防因重力卸载导致的矿物质流失，并维持骨骼生长。在为期10天的后肢悬吊期间，对体重约300克的大鼠，于臀区通过左侧坐骨神经施加1、50或100赫兹的电刺激。分析后肢骨骼的干重、矿物质含量和矿物质密度。后肢悬吊大鼠的股骨以及胫腓骨的干重和矿物质含量往往低于年龄匹配的笼养对照大鼠。然而，50赫兹和100赫兹的刺激可预防这些有害影响。即使在未受刺激的肢体中也观察到了刺激的积极作用，不过在受刺激的肢体中诱导的效果更显著。这表明，在大鼠后肢悬吊期间，较高频率的刺激诱导肌肉收缩施加负荷有利于维持骨骼生长或预防矿物质流失，或二者兼具。
