宇宙航空環境医学 Vol. 62, No. 1, 20 2025

一般演題I

4.　ミトコンドリア代謝刺激によるユニークなカウンターメジャー

大平　充宣¹，大平　宇志²，大澤　晴太³，高倉　久志³，斎藤　芳郎⁵，井澤　鉄也³，村谷　匡史⁶，
後藤　琢也⁴

¹大阪大学
²近畿大学医学部
³同志社大学スポーツ健康科学研究科
⁴同志社大学理工学研究科
⁵東北大学薬学研究科
⁶筑波大学医学医療系

Stimulation of mitochondrial metabolism as the unique countermeasure

Yoshinobu Ohira¹, Tatashi Ohira², Seita Osawa³, Hisashi Takakura³, Yoshiro Saito⁵, Tetsuya Izawa³,
Masafumi Muratani⁶, Takuya Goto⁴

¹Osaka Univ, ²Kindai Univ. Sch. Med., Grad. Sch. ³Sp. Sci. and ⁴Sci. Engineering, Doshisha Univ.,
⁵Grad. Sch. Phannaceut. Sci., Tohoku Univ., ⁶Dept Genome Biol., Inst. Med., Univ. Tsukuba

It is well-reported that the decrease in the specific activities of mitochondrial enzymes and the shift of fibers expressing from slow- to fast-twitch phenotypes, which are associated with atrophy in antigravitational muscles, are induced in response to exposure to microgravity environment.　Such phenomena are generally associated with reduced mechanical stresses and neural activities, suggesting the “Slow-down of metabolism” as one of the main causes for the detrimental physiological responses induced in micro- or partial gravity environments.　It was also suggested that oxidative stress, which is also increased following the inhibition of muscular activities, may play one of the key roles for the induction of such responses.
　Thus, we have been performing a series of studies to investigate the suitable methods for maintenance and/or improvement of muscular properties in response to metabolic stimulation, not directly rely on the intensive contraction of muscles.　The results suggested that the beneficial effects on the physiological properties were induced in response to metabolic stimulation following various models of treatments.　 The oxidative metabolic properties in skeletal muscles were stimulated, when the resting contents of high-energy phosphates, such as ATP and phosphocreatine, were chronically lowered.　The detrimental effects caused by the production of active oxygen were also modified by inhibition of oxidative stress.
　Although it is obvious that such metabolic treatment might be a great tool, stimulation of contractile activity of muscles is also essential.　Thus, addition of mild slow-rear-foot strike walking, cycling by active plantar-flexion, or passive dorsi-flexion of ankle joints, which increase the mobilization of soleus, is essential, as one of the cowntermeasures in lower gravity enviro1unent.
　This study was supported, in part, by Doshisha DREAM Project.