增强的Ca(2+) 释放和Na/Ca交换活动在过度缩的犬腹腔肌细胞中:收缩适应和心律失常之间的潜在联系
K R Sipido1, P G Volders, S H de Groot
1Laboratory of Experimental Cardiology, University of Leuven, Belgium. karin.sipido@med.kuleuven.ac.be
Circulation
|October 25, 2000
概括
在心力衰竭中,增强的-交换器活动可以改善心肌功能,但会增加由于过载和电活动改变而导致危险的腹腔失律的风险.
科学领域:
- 心血管生理学心血管生理学
- 心脏电生理学 心脏电生理学
- 心脏衰竭病理生理学 病理生理学
背景情况:
- 心室节律失常是心力衰竭和缩患者心脏突然死亡的主要原因.
- 慢性全心室阻塞 (CAVB) 狗模型表现出双心室缩和心室失律,作为研究细胞机制的宝贵工具.
- 这项研究探讨了 (Ca2+) 稳态在CAVB模型中的收缩适应和节律失调的作用.
研究的目的:
- 为了研究在慢性完全心房阻塞 (CAVB) 的收缩适应过程中Ca2+稳态的变化.
- 确定这些Ca2+处理变化是否有助于CAVB模型中心室节律失常的发展.
主要方法:
- 用CAVB从狗心脏中酶分离肌细胞.
- 评估肌细胞缩短和细胞内Ca2+处理,包括sarcoplasmic网膜 (SR) Ca2+含量和释放.
- 通过L型Ca2+通道和Na/Ca交换器测量Ca2+的流入,以及Na/Ca交换电流.
主要成果:
- 来自CAVB犬的肌细胞显示在较低的刺激频率下增强了细胞缩短,SR Ca2+释放和SR Ca2+含量.
- 通过L型Ca2+通道的Ca2+流入保持不变.
- 通过Na/Ca交换器增加的Ca2+流入有助于SR Ca2+负载,并观察到更大的内向Na/Ca交换电流. 这些变化在左心室比右心室更明显.
结论:
- 增强的Na/Ca交换活动可能有助于改善CAVB的收缩功能.
- 然而,这种增加的活性也会增加心律失常的易感性,因为它会促进Ca2+的过载.
- 它可以导致动作潜力的延长,并在自发的Ca2+释放过程中增强节律失调电流,从而促进心室节律失调.
相关概念视频
The Role of Ion Channels in Neuronal Computation
3.2K
A postsynaptic neuron usually receives numerous impulses from several other presynaptic neurons. The axon hillock of the postsynaptic neuron integrates all these signals and determines the likelihood of firing an action potential.
Sometimes a single EPSP is strong enough to induce an action potential in the postsynaptic neuron. However, multiple presynaptic inputs must often create EPSPs around the same time for the postsynaptic neuron to be sufficiently depolarized to fire an action potential....
Sometimes a single EPSP is strong enough to induce an action potential in the postsynaptic neuron. However, multiple presynaptic inputs must often create EPSPs around the same time for the postsynaptic neuron to be sufficiently depolarized to fire an action potential....
3.2K
pH Regulation in Cells
5.4K
pH plays a critical role in maintaining normal cellular activities. It helps maintain the structure and function of various proteins, dictates the charge on cellular membranes, and is crucial for metabolic reactions inside the cell. Moreover, cells use the energy from the proton motive force to generate ATP.
Cytosolic pH
Under physiological conditions, the cytosolic pH is slightly more acidic than the extracellular pH. However, cells must prevent further acidification of their cytosol to...
Cytosolic pH
Under physiological conditions, the cytosolic pH is slightly more acidic than the extracellular pH. However, cells must prevent further acidification of their cytosol to...
5.4K
G-Protein Gated Ion Channels
5.5K
GPCRs are primarily responsible for our sense of smell, taste, and vision. The binding of a sensory stimulus activates GPCR to stimulate effector proteins, many of which are ion channels in the sensory organs. GPCRs modulate the opening and closing of the target ion channels either directly by binding them, or by releasing second messengers that activate these channels. As ions move across the membrane, the membrane potential is altered, which induces an appropriate response.
Sensory...
Sensory...
5.5K
Feedback Regulation of Calcium Concentration
2.9K
Calcium is an essential signaling molecule required for various cellular functions. Calcium pumps and ion channels on cell and organellar membranes, such as those on the endoplasmic reticulum (ER), regulate calcium concentrations inside the cell. They remain closed, keeping the cytosolic calcium levels low at a resting state.
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
2.9K
Ligand-Gated Ion Channel Receptor: Gating Mechanism
4.6K
Ligand-gated ion channels are transmembrane proteins that play a vital role in intercellular communication and functions of the nervous system. They allow the influx of ions across the membrane once the neurotransmitter binds, allowing the subsequent transmission of electrical excitation across the neurons. Other ligand-gated ion channels, like the γ-aminobutyric acid (GABA) receptor, permit anions like chloride into the cells on the binding of the GABA molecule. Their entry into the cell...
4.6K
Relaxation of Skeletal Muscles
9.7K
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....
9.7K


