Contractile responses of rat fast‐twitch and slow‐twitch muscles to glucocorticoid treatment
Contractile responses of rat fast‐twitch and slow‐twitch muscles to glucocorticoid treatment
复制标题
大鼠快肌和慢肌对糖皮质激素治疗的收缩反应
作者：
P. Gardiner;V. Edgerton
为了确定长期糖皮质激素治疗是否会影响快肌和慢肌的速度和力量相关特性，在大鼠中以2 mg/kg/天的剂量注射曲安奈德14天后，测量了比目鱼肌和腓肠肌的原位收缩特性。对两块肌肉的收缩速度或强度均无影响。给药组（43.0 ± 1.0 msec）的比目鱼肌张力峰值时间显著长于对照组（38.7 ± 0.7 msec）;然而，这归因于“活动状态”持续时间的延长，因为给药组肌肉也显示抽搐-强直比率显著升高。腓肠肌（对照组的198% ± 19%）中处理诱导的特异性抽搐张力增强比比目鱼肌（对照组的153% ± 9%）更明显。对类固醇治疗反应的差异可能反映了快肌和慢肌膜系统的结构和功能差异。
In an attempt to determine whether chronic glucocorticoid treatment affects speed‐ and strength‐related properties of fast‐twitch muscle and slow‐twitch muscle, in‐situ contractile properties of soleus and gastrocnemius muscles were measured in rats after 14 days on a regimen of triamcinolone acetonide injected at a dosage of 2 mg/kg/day. No effects on contractile speed or strength were noted for either muscle. The time to peak tension in soleus muscle was significantly longer in the treated group (43.0 ± 1.0 msec) than in the control group (38.7 ± 0.7 msec); however, this was attributed to a prolongation of “active state” duration, as suggested by the fact that treated muscles also showed significantly elevated twitch‐tetanus ratios. The treatment‐induced enhancement of the specific twitch tension was more pronounced in the gastrocnemius muscles (198% ± 19% of control) than in the soleus muscles (153% ± 9% of control). The difference in response to steroid treatment may reflect structural and functional difference in fast‐ and slow‐muscle membrane systems.