Kawano Fuminori
School of Health and Sport Sciences, Osaka University.
Biol Sci Space. 2004 Nov;18(3):104-5.
We reported that the levels of electromyogram in soleus muscle and the afferent neurogram recorded at L5 segmental level of the spinal cord were instantly decreased in response to exposure to microgravity (micro-G) environment created during a parabolic flight, although these activities were constantly presented at 1-G. It was also observed that the soleus muscle length was passively shortened in micro-G due to the plantarflexion of ankle joint. Similar phenomena were also induced by acute hindlimb suspension at 1-G. Further, the soleus muscle atrophied, if the dorsal root at L5 was transected. These results suggested that the unloading-related effects on muscle are closely associated with the inhibition of the afferent input. However, effects of gravity on most of the cells in the whole body can not be removed, although hindlimb suspension can inhibit the antigravity activity of rat hindlimb muscles. And parabolic flight can create micro-G only for a short period of time. Further, effects of hypergravity before and after micro-G are unavoidable. Therefore, further experiments utilizing space environment are essential.
我们报告称，比目鱼肌的肌电图水平以及在脊髓L5节段水平记录的传入神经电图，在暴露于抛物线飞行期间产生的微重力（micro-G）环境时会立即降低，尽管这些活动在1-G时持续存在。还观察到，由于踝关节的跖屈，比目鱼肌长度在微重力环境下被动缩短。在1-G条件下急性后肢悬吊也会诱发类似现象。此外，如果切断L5的背根，比目鱼肌会萎缩。这些结果表明，与卸载相关的对肌肉的影响与传入输入的抑制密切相关。然而，尽管后肢悬吊可以抑制大鼠后肢肌肉的抗重力活动，但重力对全身大多数细胞的影响无法消除。而且抛物线飞行只能在短时间内产生微重力。此外，微重力前后的超重影响是不可避免的。因此，利用太空环境进行进一步实验至关重要。
