拉伸激活可以对抗快速收缩的小鼠骨肌纤维因疲劳而失去的力量
Philip C Woods1, Douglas M Swank2,3, Mark S Miller1
1Department of Kinesiology, School of Public Health and Health Sciences, University of Massachusetts, Amherst, MA, USA.
The Journal of general physiology
|August 11, 2025
概括
拉伸激活 (SA) 通过增加其对快速收缩纤维总张力的贡献来增强疲劳期间的肌肉力量. 这种现象可能会改善肌肉的耐力,这些肌肉在缩短之前会延长.
科学领域:
- 肌肉生理学 肌肉生理学
- 骨肌肉机械学 骨肌肉机械学
- 运动科学运动科学
背景情况:
- 拉伸激活 (SA) 是肌肉拉伸后的力量增强,在昆虫和心肌中至关重要.
- 从历史上看,由于低生理酸盐水平,SA在骨肌肉中被认为是无关紧要的.
- 最近的发现表明,高酸盐度 ([Pi]) 可以增加小鼠底部纤维中的SA,这表明它在抗疲劳方面发挥了作用.
研究的目的:
- 研究SA在疲劳条件下的骨肌肉中的作用.
- 确定SA如何在疲劳期间对不同肌肉蛋白重链 (MHC) 纤维类型的强力产生作出贡献.
- 评估疲劳引起的 ([Ca2+]) 和[Pi]变化对SA的影响.
主要方法:
- 在活跃,高[Ca2+]疲劳和低[Ca2+]疲劳条件下,SA被测量在小鼠的肌肉纤维 (MHC I,IIA,IIX,IIB) 中.
- 量化了同度张力 (F0) 和SA张力 (FSA).
- 计算了SA对总张力的相对贡献 (FSA/[F0 + FSA]).
主要成果:
- 在快速收缩的MHC II纤维中,SA张力 (FSA) 在疲劳时保持不变或增加,尽管活性张力降低 (F0).
- 在疲劳条件下,SA对总张力的贡献在MHC II纤维中显著增加 (58-114%).
- 与MHC II纤维相比,SA张力峰值在MHC I纤维中是最小的,特别是在疲劳期间.
结论:
- 在疲劳期间,SA显著增强快速收缩的MHC II骨肌纤维的力量产生.
- 增加SA对疲劳下紧张的相对贡献表明它在改善肌肉耐力方面发挥了作用.
- 伸缩动脉可能是肌肉经历拉伸缩短周期的关键机制,特别是在长时间或艰苦的活动中.
相关概念视频
01:20Motor Unit Stimulation
2.0K
When the neuron of a motor unit fires an action potential, it triggers a series of events, leading to a twitch contraction in the muscle fibers. The process of excitation-contraction coupling is crucial in relaying the action potential to the muscle fibers.
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
2.0K
01:22Muscle Stimulation Frequency
2.6K
The contraction strength of muscles is regulated by motor neurons, which modulate the frequency of action potentials dispatched to the motor units based on the body's requirements. This process of varying the muscle stimulation frequency allows muscles to contract with a force that is precisely tailored to the needs of the moment, whether lifting a feather or a heavy box.
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
2.6K
01:29Relaxation of Skeletal Muscles
3.8K
The period of muscle contraction primarily influences the duration of stimulation at the neuromuscular junction (NMJ), the presence of free calcium ions in the sarcoplasm, and the availability of energy or ATP to support contractions.
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open....
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open....
3.8K
01:25Smooth Muscle Contraction
3.9K
Smooth muscle contraction is a complex process vital for various bodily functions, from maintaining blood vessel tension to facilitating the movement of food through the digestive tract. Unlike striated muscles, smooth muscle contraction begins more slowly and lasts longer.
The onset of contraction is triggered by an increase in calcium ions within the sarcoplasm, similar to the process in striated muscle. However, smooth muscles have a relatively smaller reservoir of the sarcoplasmic...
The onset of contraction is triggered by an increase in calcium ions within the sarcoplasm, similar to the process in striated muscle. However, smooth muscles have a relatively smaller reservoir of the sarcoplasmic...
3.9K
01:26Cross-bridge Cycle
118.3K
As muscle contracts, the overlap between the thin and thick filaments increases, decreasing the length of the sarcomere—the contractile unit of the muscle—using energy in the form of ATP. At the molecular level, this is a cyclic, multistep process that involves binding and hydrolysis of ATP, and movement of actin by myosin.
118.3K
01:20Excitation-Contraction Coupling in Skeletal Muscles
9.5K
Excitation-contraction coupling is a series of events that occur between generating an action potential and initiating a muscle contraction. It occurs at the triad, a structure found in skeletal muscle fibers that comprise a T-tubule and terminal cisternae of the sarcoplasmic reticulum on each side. These triads are visible in longitudinally sectioned muscle fibers. They are typically located at the A-I junction — the junction between the A and I bands of the sarcomere.
When an action...
When an action...
9.5K