静脈性タヒカルディアの際に,リエントラント回路の異なる領域の細胞の改造
Shigeo Baba1, Wen Dun, Candido Cabo
1Department of Pharmacology, Center for Molecular Therapeutics, Columbia University, New York, NY, USA.
Circulation
|October 6, 2005
まとめ
エピカルディアの境界地帯におけるナトリウム (INa) とカルシウム (ICaL) の流れの地域差は,心臓発作後の再侵入刺激を安定させる. これらのイオン電流の変化は,機能的なブロックラインを作り出し,心臓発作の心臓発作における持続的な心室動脈不全を促進します.
科学分野:
- 心血管生理学 心血管の生理学
- 心臓電気生理学 心臓電気生理学
- アリズミーのメカニズム アリズミーのメカニズム
背景:
- アニゾトロプ的リエントラント刺激は,心臓梗塞の犬の心臓の表心臓境界地帯 (EBZ) で観察されます.
- 再入力の安定化は,ブロックの機能的なラインの形成と関連しています.
- EBZ細胞における地域的なイオン電流の差異が,これらのブロックラインの原因であると仮定されています.
研究 の 目的:
- 心臓発作のEBZにおける再侵入回路をマッピングする.
- リエントラント回路の中央 (IZc) と外部 (IZo) 経路細胞間のイオン電流の地域差異を調査する.
- これらのイオン電流の違いが再入力の安定性に寄与するかどうかを判断する.
主な方法:
- 17匹の犬の心臓発作で,持続した心室動脈性急性心臓発作の際に再発回路のマッピング.
- リエントラント回路の中央 (IZc) および外部 (IZo) 経路から細胞を分散させる. 電気生理学的研究のために.
- 2D EBZのコンピュータシミュレーションは,測定されたイオン電流差を組み込みます.
主要な成果:
- IZc 細胞と IZo 細胞の両方のINa 密度が低下し,動力学が変化し,両者の間で顕著な動力学的な差異がある.
- 心臓発作ゾーンの細胞で観察されたNav1.5ナトリウムチャネルの構造的改造.
- IZcとIZoでは同様のICaLの低下がみられたが,IZcでは動態が変化した.
- シミュレーションでは,INaまたはICaLの差異だけでは再入力を安定させることができなかったが,組み合わせた差異は回路を安定させ,ブロックの線を形成することを示した.
結論:
- リエントラント回路の中央と外側の経路の細胞の間には,INaとICaLの性質の違いがあります.
- これらのイオン電流の差異は,特に組み合わせると,改造されたEBZ基板への再入りを安定させます.
- この研究は,心臓発作後の継続的な心律不整に寄与する機能的なブロックラインのイオン的基礎を解明しています.
関連する概念動画
01:13The Cardiac Cycle
The heart beats rhythmically in a sequence called the cardiac cycle—a rapid coordination of contraction (systole) and relaxation (diastole).
The Process
Electrical signals—sent from the sinoatrial (SA) node in the right atrial wall to the atrioventricular (AV) node between the right atrium and right ventricle—cause both atria to simultaneously contract. When the signal reaches the AV node, it pauses for approximately a tenth of a second, allowing the atria to contract and empty blood into the...
The Process
Electrical signals—sent from the sinoatrial (SA) node in the right atrial wall to the atrioventricular (AV) node between the right atrium and right ventricle—cause both atria to simultaneously contract. When the signal reaches the AV node, it pauses for approximately a tenth of a second, allowing the atria to contract and empty blood into the...
01:29Blood Flow
Blood is pumped by the heart into the aorta, the largest artery in the body, and then into increasingly smaller arteries, arterioles, and capillaries. The velocity of blood flow decreases with increased cross-sectional blood vessel area. As blood returns to the heart through venules and veins, its velocity increases. The movement of blood is encouraged by smooth muscle in the vessel walls, the movement of skeletal muscle surrounding the vessels, and one-way valves that prevent backflow.
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...
01:16Heart Valves
The human heart is a complex organ with an intricate system of valves that regulate blood flow. There are two main types of valves: atrioventricular (AV) valves and semilunar valves.
The AV valves prevent the backflow of blood from the ventricles to the atria during ventricular contraction. These valves function with the assistance of the chordae tendineae and papillary muscles. When the ventricles are relaxed, the chordae tendineae are slack, allowing blood to flow from the atria into the...
The AV valves prevent the backflow of blood from the ventricles to the atria during ventricular contraction. These valves function with the assistance of the chordae tendineae and papillary muscles. When the ventricles are relaxed, the chordae tendineae are slack, allowing blood to flow from the atria into the...
01:29Cardiac Cycle
The cardiac cycle refers to the sequence of events that occur in the heart from the beginning of one heartbeat to the next. It's characterized by alternating periods of contraction (systole) and relaxation (diastole) of the heart muscles.
During the cardiac cycle, blood flow through the heart is regulated entirely by changing pressure gradients. This sequence of events begins with the heart in a state of total relaxation, known as mid-to-late diastole, during which blood passively flows from...
During the cardiac cycle, blood flow through the heart is regulated entirely by changing pressure gradients. This sequence of events begins with the heart in a state of total relaxation, known as mid-to-late diastole, during which blood passively flows from...
01:18Physiology of the Heart: The Cardiac Cycle
The cardiac cycle describes the events from one heartbeat to the next. It includes three main phases: diastole, atrial systole, and ventricular systole, all driven by changes in chamber pressures and the function of heart valves.
Diastole: The Relaxation Phase
During diastole, all four heart chambers relax. The atrioventricular (AV) valves open, and the semilunar valves close. This phase sees the lowest chamber pressures, promoting ventricular filling. Venous blood enters the heart through the...
Diastole: The Relaxation Phase
During diastole, all four heart chambers relax. The atrioventricular (AV) valves open, and the semilunar valves close. This phase sees the lowest chamber pressures, promoting ventricular filling. Venous blood enters the heart through the...