Interrelationships of contraction time, Vmax, and myosin ATPase after spinal transection.
Interrelationships of contraction time, Vmax, and myosin ATPase after spinal transection.
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脊髓横断后收缩时间、Vmax 和肌球蛋白 ATP 酶的相互关系。
DOI：
10.1152/jappl.1984.56.6.1594
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
Edgerton,VR
中科院分区：
文献类型：
--
作者：
Roy,RR;Sacks,RD;Baldwin,KM;Short,M;Edgerton,VR
研究了低位胸髓切断后后肢伸肌的力学和生化特性之间的相互关系。在2周时将小猫刺化（Sp）并维持6-12个月。一些Sp动物在跑步机上运动（Sp-E）25-30分钟/天，5天/周。在原位收缩特性的慢收缩比目鱼肌（SOL）和快收缩内侧腓肠肌（MG）的正常（N），Sp，和Sp-E猫。运动不影响大多数参数;因此Sp和Sp-E组被集体考虑。SOL和MG的横截面积（CSA）分别减少了43%和32%。SOL的比张力（张力/CSA）保持不变，但MG降低（P <0.05）。SOL的收缩时间（CT）和半松弛时间显著缩短，但MG无变化。最大缩短速度（Vmax）和肌球蛋白ATP酶（μ mol × mg-1 × min-1）增加（P <0.05），在两组的SOL和SP的MG。频率-张力反应的两个肌肉转向类似的“更快”的肌肉。这些结果证实了Vmax和CT存在相对独立的调节机制，并表明肌球蛋白ATP酶水平与Vmax的关系比CT更密切。虽然SOL的变化与慢纤维转化为快纤维的假设一致，但MG的Vmax和肌球蛋白ATP酶升高表明，在“快”纤维类型类别中也发生了显著变化。
Interrelationships of selected mechanical and biochemical properties of hindlimb extensor muscles following low thoracic cord transection were studied. Kittens were spinalized (Sp) at 2 wk and maintained for 6–12 mo. Some Sp animals were exercised (Sp-E) on a treadmill 25–30 min/day, 5 days/wk. In situ contractile properties of the slow-twitch soleus (SOL) and fast-twitch medical gastrocnemius (MG) muscles of normal (N), Sp, and Sp-E cats were determined. Exercise did not affect most parameters; thus Sp and Sp-E groups are considered collectively. The cross-sectional areas (CSA) of the SOL and MG decreased by 43 and 32%, respectively. Specific tension (tension/CSA) was maintained in the SOL but decreased (P less than 0.05) in the MG. Contraction time (CT) and half-relaxation time were significantly shorter in the SOL but unchanged in the MG. Maximum shortening velocity (Vmax) and myosin ATPase (mumol X mg-1 X min-1) increased (P less than 0.05) in the SOL of both groups and the MG of Sp. Frequency-tension responses of both muscles shifted toward that resembling a “faster” muscle. These results substantiate the existence of relatively independent regulatory mechanisms for Vmax and CT and show that myosin ATPase levels are more closely related to Vmax than CT. Although the changes in the SOL were consistent with the hypothesis that slow fibers are converted to fast, the elevated Vmax and myosin ATPase of the MG suggest that significant changes also occur within a “fast” fiber-type category.