カルシウム活性化されたCl (−) 電流は,単一プルキンゼ細胞と心室筋細胞の分極化後の遅延に寄与する
A O Verkerk1, M W Veldkamp, L N Bouman
1Department of Physiology, Academic Medical Center, University of Amsterdam, The Netherlands. a.o.verkerk@amc.uva.nl
Circulation
|June 7, 2000
まとめ
心臓細胞内の一時的な内流 (I(ti)) は,塩化物 (Cl-) とナトリウム-カルシウム (Na+-Ca2+) 交換電流の両方を含む. Cl-電流成分を遮断することは,遅延後のデポラライゼーション (DADs) を減らすことにより,不律を予防するのに役立ちます.
科学分野:
- 心臓電気生理学 心臓電気生理学
- イオンチャンネル生理学 イオンチャンネル生理学
- 心血管薬理学について
背景:
- 暫定的な内向き電流 (I(ti)) は,心律不整症の重要な要因である遅延後分極化 (DADs) の基礎となっている.
- I ((ti) のイオンメカニズムは,心室筋細胞とプルキンジェ線維の間で異なっており,以前の研究では,Na+-Ca2+交換,Cl-電流,非選択的離子電流が関与していた.
研究 の 目的:
- 単一羊のPurkinjeおよび心室筋細胞におけるI ((ti)) のイオン基を解明する.
- I(ti) のCl-電流成分を阻害する抗不律性の可能性を調査する.
主な方法:
- 全細胞パッチクランプ電気生理学は,単離された羊のプルキンジェと心室筋細胞に採用されました.
- I (((ti) は,ノレピネフリンの存在下での反復的脱極化を使用して誘発されました.
- アニオンブロッカーの4,4'-二酸化イソチオシアノシヤノチルベン-2,2'-ジスルフォン酸 (DIDS) とNa+-Ca2+交換ブロックの効果が評価されました.
主要な成果:
- I(ti) は,両方の細胞タイプにおいて,負の電位で入流電流と,正の電位で出流電流を示した.
- DIDSは,外側のコンポーネントを完全に遮断し,内側のコンポーネントをわずかに抑制しました.
- DIDSに敏感なI ((ti)) コンポーネントは,Cl-電流と一致する外向きの修正であり,DIDSに敏感でないコンポーネントは,Na+-Ca2+交換ブロックによって廃止されました.
結論:
- Purkinje と Ventricular myocytes の両方において,イオンは2つの異なるイオンメカニズムによって媒介される:Cl-電流とNa+-Ca2+交換電流.
- I(ti) のCl-電流成分を遮断すると,DADの振幅が著しく低下し,活性が誘発され,抗不律性効果の可能性を示唆する.
さらに関連する動画
06:22Isolation of High Quality Murine Atrial and Ventricular Myocytes for Simultaneous Measurements of Ca2+ Transients and L-Type Calcium Current
Published on: November 3, 2020
08:11Voltage-Dependent Potassium Current Recording on H9c2 Cardiomyocytes via the Whole-Cell Patch-Clamp Technique
Published on: November 11, 2022
関連する概念動画
01:18Patch Clamp
Many fundamental cell functions such as muscle contraction and nerve transmission rely on the electrical signals produced by the movement of positively and negatively charged ions across the cell membrane. One competent method to record current flowing across the whole cell or single ion channel is the patch-clamp technique.
In this method, a glass micropipette containing electrolyte solution is tightly sealed against a small portion of the cell membrane. As a result, a patch of the cell...
In this method, a glass micropipette containing electrolyte solution is tightly sealed against a small portion of the cell membrane. As a result, a patch of the cell...
01:19The Role of Ion Channels in Neuronal Computation
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.
01:27Feedback Regulation of Calcium Concentration
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...
01:18Antihypertensive Drugs: Action of Calcium Channel Blockers
Calcium ions are essential to contract smooth muscle cells in blood vessels. They enter these cells through voltage-dependent calcium channels, specifically L-type calcium channels in the cell membrane. These L-type calcium channels are integral to the excitation-contraction coupling process in smooth muscle. When a stimulus is received by smooth muscle cells, their membrane depolarizes. This alteration in membrane potential instigates the opening of L-type calcium channels. As a result,...
01:20Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers
Class IV antiarrhythmic drugs, such as verapamil and diltiazem, block calcium channels. They primarily affect the heart, slowing the conduction in calcium-dependent tissues like the SA and AV nodes. These drugs manage reentrant supraventricular tachycardia (SVT) and reduce ventricular rate in atrial flutter/fibrillation.
Verapamil, a calcium channel blocker, inhibits calcium movement across myocardial cell membranes and vascular smooth muscle. This results in the dilation of coronary and...
Verapamil, a calcium channel blocker, inhibits calcium movement across myocardial cell membranes and vascular smooth muscle. This results in the dilation of coronary and...
01:30Cardiac Action Potential
Cardiac action potentials are essential for proper heart function, enabling the rhythmic contractions needed for adequate blood circulation. Nodal cells and Purkinje fibers, specialized for electrical conduction, generate these action potentials.
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials