在完整的人类心肌中稳定状态力和细胞内[Ca2+]之间的关系. 肌纤维细胞对Ca2+的反应指数
1Department of Cellular and Molecular Physiology, Harvard Medical School, Boston, MA.
Circulation
|October 1, 1990
概括
这项研究引入了一种新的方法来测量人类心脏肌肉中的稳定状态力和细胞内度 ([Ca2+]i). 研究结果显示,心脏肌肉中稳定状态和抽收缩之间存在明显的敏感性差异.
科学领域:
- 心脏病学 心脏病学
- 身体生理学 身体生理学
- 生物物理学的生物物理.
背景情况:
- 了解在心肌收缩中的作用对于诊断和治疗心脏病至关重要.
- 评估肌纤维敏感性的现有方法通常涉及药理干预或单独的制剂,限制其直接适用于完整的肌肉功能.
研究的目的:
- 开发和验证一种新的方法来测量稳定状态力和细胞内度 ([Ca2+]i) 在完整的人类腹腔轨道上,而不使用药物剂.
- 为了比较和对比三种不同的方法来评估肌纤维敏度:剥皮纤维中的力-[Ca2+]关系,峰值抽力-[Ca2+]i关系和完整肌肉中的稳定状态力-[Ca2+]i关系.
主要方法:
- 完好无损的人类状肌肉被充满了equorin,一种对敏感的生物发光蛋白.
- 通过化 (15-20 Hz刺激) 实现了稳定状态收缩激活,以快速达到稳定力和[Ca2+]i.
- 强力-[Ca2+]i关系是通过在缩期间改变细胞外度 ([Ca2+]o) 来构建的,并使用希尔方程进行分析. 与峰值抽力-[Ca2+]i关系和剥皮纤维制剂进行了比较.
主要成果:
- 这种新的方法成功地测量了稳定状态力和[Ca2+]i在化完整的人类轨道上.
- 来自tetani的平稳状态力-[Ca2+]i关系与峰值抽力-[Ca2+]i关系显著不同,后者转向更高的[Ca2+]i.
- 脱皮纤维制剂显示出独立于氨酸的敏感性,不同于完整的肌肉,氨酸影响了动力学.
结论:
- 该研究成功地建立了一种非药理学方法,用于评估完整的人类心脏肌肉中稳定状态敏感度.
- 稳定状态和峰值抽力-[Ca2+]i关系之间观察到的差异表明了不同的潜在机制,稳定状态反映了肌纤维敏感性,峰值抽反映了瞬态动态.
- 这些发现提供了更准确的评估肌纤维敏感性在本地心脏组织,相关的理解心脏病理生理学.
相关概念视频
01:20Excitation-Contraction Coupling in Skeletal Muscles
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 potential...
When an action potential...
01:29Relaxation 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.
01:27Specialized Characteristics of Cardiac Muscles
The primary role of cardiac muscles is to propel blood throughout the cardiovascular system. The cardiac muscle cells, or cardiomyocytes, exhibit specialized characteristics that allow them to perform this function.
Cardiac muscle cells are smaller than skeletal muscles, averaging 10–20 mm in diameter and 50–100 mm in length. However, they have large energy demands for continuous contraction and relaxation. This energy is almost exclusively derived from aerobic metabolism of energy reserves in...
Cardiac muscle cells are smaller than skeletal muscles, averaging 10–20 mm in diameter and 50–100 mm in length. However, they have large energy demands for continuous contraction and relaxation. This energy is almost exclusively derived from aerobic metabolism of energy reserves in...
01:25Smooth 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...