Yamazaki T, Haida N, Tachino K
School of Health Sciences, Faculty of Medicine, Kanazawa University, Kanazawa 920-0942, Japan.
J Jpn Phys Ther Assoc. 1998;1(1):19-24. doi: 10.1298/jjpta.1.19.
The purpose of this study was to investigate the effects of weight bearing at varying intervals in suppressing the progression of disuse muscle atrophy, while setting the total daily weight bearing time constant. Disuse muscle atrophy was induced by 2-week hindlimb suspension. Thirty male Wistar rats ( weight : 215 ± 8 g ) were divided into 6 groups ( 5 rats/group ) : control (CON), suspension alone (SUS), two sessions of 30-minute weight bearing at intervals of 4, 8, and 12 hours during suspension, and one session of 60-minute weight bearing at intervals of 24 hours during suspension. Weight bearing was done each day during the daytime. Histochemical staining, followed by morphometrical analysis using NIH Image, demonstrated that the cross-sectional area of type I fiber in SUS was 44% of that in CON, while in the weight bearing groups ranged from 62 to 70%. The proportion of type I fibers was lower in SUS and tended to increase as the interval of weight bearing become longer, indicating the effects of weight bearing at intervals of 12 and 24 hours. For both types I and II, the distribution of muscle fiber size indicated that weight bearing at longer intervals was more effective in keeping the cross-sectional areas of muscle fibers closed to that in CON. In conclusion, when suppressing the progression of disuse atrophy of rat soleus muscle by weight bearing of one hour per day, the results suggest that the weight bearing intervals is important factor.
本研究的目的是在设定每日总负重时间恒定的情况下，探究不同间隔的负重对抑制废用性肌肉萎缩进展的影响。通过2周的后肢悬吊诱导废用性肌肉萎缩。将30只雄性Wistar大鼠（体重：215±8 g）分为6组（每组5只）：对照组（CON）、单纯悬吊组（SUS）、在悬吊期间每隔4、8和12小时进行两次30分钟负重的组，以及在悬吊期间每隔24小时进行一次60分钟负重的组。每天在白天进行负重。组织化学染色，随后使用NIH Image进行形态计量分析，结果表明，SUS组中I型纤维的横截面积为CON组的44%，而在负重组中，这一比例在62%至70%之间。SUS组中I型纤维的比例较低，且随着负重间隔时间延长有增加趋势，表明12小时和24小时间隔负重的效果。对于I型和II型纤维，肌纤维大小分布表明，间隔时间更长的负重对于使肌纤维横截面积更接近CON组更有效。总之，当通过每天1小时的负重来抑制大鼠比目鱼肌废用性萎缩的进展时，结果表明负重间隔是一个重要因素。
