在放松过程中快速缩短会增加激活,并改善缩性表现
M W Watkins1, A Higashiyama, Z Chen
1Cardiology Unit, University of Vermont, Burlington 05401, USA.
Circulation
|September 15, 1996
概括
缩后的排泄会提高心脏收缩能力,而不依赖于终端透缩体积. 这种效应,特别是在快速喷射的情况下,表明可用于激活和改善心室性能.
科学领域:
- 心血管生理学心血管生理学
- 心脏机能学是指心脏机能学
- 室腔功能 室腔功能
背景情况:
- 以前的研究经常将积极的喷射效应归因于长度依赖激活.
- 一些研究表明,与喷射相关的收缩增强独立于终端透缩体积 (EDV) 史.
- 目前的研究旨在澄清这些在完整的心室中独立于喷射的机能效应.
研究的目的:
- 描述喷射独立的收缩增强的机能效应.
- 研究快速体积减小 (VR) 对心室功能的作用.
- 探索喷射,循环和氧气消耗之间的关系.
主要方法:
- 隔离的子心脏使用伺服电机研究了控制的左心室体积减小 (VR) 在末端缩.
- 实验涉及同体积收缩,缓慢VR (5.0 +/- 0.9EDV/s) 和快速VR (26.8 +/- 5.1EDV/s) 在恒定的EDV.
- 测量了左心室的氧气消耗 (VO2) 和非机械的VO2 (使用2,3-butanedione monoxime).
主要成果:
- 音量减小 (VR) 显著提高了收缩性,相比同体体拍,在快速VR时效果更大.
- 快速VR使发育压力增加了15%,最大dP/dT增加了17%,Emax增加了13% (P < .01).
- 快速VR的总体VO2降低了8%,但非机械VO2增加了26%,表明循环增加.
结论:
- 压缩后排气积极影响除了长度依赖激活之外的心室性能.
- 这些发现表明,在喷射过程中可用于激活的可用的增加.
- 喷射似乎与肌纤维纤维缩短和激活器循环有积极的相互作用.
相关概念视频
Relaxation of Skeletal Muscles
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.
Motor Unit Stimulation
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...
Muscle Stimulation Frequency
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...
Smooth Muscle Contraction
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...
Exercise and Cardiac Output
Regular physical activity is essential for maintaining cardiovascular health, with aerobic exercises being particularly effective. According to the American Heart Association, 150 minutes of moderate to intense aerobic exercise per week is recommended for a healthy heart. Aerobic activities may include brisk walking, running, bicycling, cross-country skiing, and swimming, ideally performed three to five times per week.
Sustained exercise increases the muscles' oxygen demand, which can be met...
Sustained exercise increases the muscles' oxygen demand, which can be met...
Exercise and Cardiovascular Response
Exercise significantly impacts cardiovascular response, which is crucial for understanding patient health and designing effective treatment plans.
Light to moderate physical activity initiates a series of interconnected responses in the body. The heart rate modestly increases in anticipation of the workout, followed by widespread vasodilation as oxygen consumption by skeletal muscles increases. This results in decreased peripheral resistance, increased capillary blood flow, and accelerated...
Light to moderate physical activity initiates a series of interconnected responses in the body. The heart rate modestly increases in anticipation of the workout, followed by widespread vasodilation as oxygen consumption by skeletal muscles increases. This results in decreased peripheral resistance, increased capillary blood flow, and accelerated...


