Yamazaki Toshiaki, Yokogawa Masami, Tachino Katsuhiko
Division of Health Science, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942, Japan.
J Jpn Phys Ther Assoc. 2009;12(1):13-9. doi: 10.1298/jjpta.12.13.
Clinically, disuse muscle atrophy is often seen among patients who are severely debilited and are on prolonged bed rest. Common physical therapy interventions are not successful in preventing disuse muscle atrophy early in the medical treatment of critically ill patients. In situations such as this, the use of a β 2-adrenergic agonist such as clenbuterol (Cb) may be of benefit in preventing atrophy. Also, recent studies have suggested that stretching is possible in preventing disuse muscle atrophy and the decline in muscle strength. The objective of this study was to evaluate the effects of Cb medication combined with stretching (ST) on rat soleus muscle (SOL) during the progression of disuse muscle atrophy.
Thirty-five male Wistar rats were used in this study.
The rats were divided into five groups: control (CON), hindlimb-unweighting (HU) only, HU+ST, HU+Cb medication, and HU+ST+Cb groups. The right SOL in stretching groups was maintained a stretched position for one hour daily by passively dorsiflexing the ankle joint under non-anesthesia. The experimental period was 2 weeks.
In the ST group, peak twitch tension per cross-sectional area in soleus muscle was significantly larger than in the Cb group, while there was no significant difference between the CON and ST groups. The conversion of type I to type II fibers that was observed in the Cb group was not recognized in the combined ST and Cb group.
Distinct effect of combined stretching and Cb medication was not recognized statistically. The results indicate that Cb affects muscle morphological characteristics while stretching affects contractile properties. These data suggest that a combined ST and Cb intervention considered the type-specificity of muscle fiber may be need more consideration for preventing disuse muscle atrophy and the decline in muscle strength.
临床上，废用性肌肉萎缩常见于严重虚弱且长期卧床休息的患者中。在危重症患者的早期治疗中，常见的物理治疗干预措施在预防废用性肌肉萎缩方面并不成功。在这种情况下，使用β2肾上腺素能激动剂如克伦特罗（Cb）可能有助于预防萎缩。此外，最近的研究表明，拉伸可能有助于预防废用性肌肉萎缩和肌肉力量下降。本研究的目的是评估在废用性肌肉萎缩进展过程中，Cb药物联合拉伸（ST）对大鼠比目鱼肌（SOL）的影响。
本研究使用了35只雄性Wistar大鼠。
将大鼠分为五组：对照组（CON）、仅后肢去负荷组（HU）、HU+ST组、HU+Cb药物组和HU+ST+Cb组。拉伸组的右侧比目鱼肌在非麻醉状态下通过被动背屈踝关节，每天保持拉伸姿势1小时。实验期为2周。
在ST组中，比目鱼肌每横截面积的峰值抽搐张力显著大于Cb组，而CON组和ST组之间无显著差异。在Cb组中观察到的I型纤维向II型纤维的转变在ST和Cb联合组中未观察到。
联合拉伸和Cb药物的明显效果在统计学上未得到认可。结果表明，Cb影响肌肉形态特征，而拉伸影响收缩特性。这些数据表明，考虑到肌纤维类型特异性的ST和Cb联合干预可能需要更多的考虑来预防废用性肌肉萎缩和肌肉力量下降。
