Gap Junction Channels and Cardiac Impulse Propagation
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- 作者：Thomas Desplantez ; Emmanuel Dupont ; Nicholas J. Severs and Robert Weingart
- 关键词：Heart ; Gap junction ; Connexin ; Impulse propagation ; Disease
- 刊名：Journal of Membrane Biology
- 出版年：2007
- 出版时间：August, 2007
- 年：2007
- 卷：218
- 期：1-3
- 页码：13-28
- 全文大小：544.5 KB
- 刊物类别：Biomedical and Life Sciences
- 刊物主题：Life Sciences
Biochemistry
Human Physiology - 出版者：Springer New York
- ISSN：1432-1424
文摘
The role of gap junction channels on cardiac impulse propagation is complex. This review focuses on the differential expression of connexins in the heart and the biophysical properties of gap junction channels under normal and disease conditions. Structural determinants of impulse propagation have been gained from biochemical and immunocytochemical studies performed on tissue extracts and intact cardiac tissue. These have defined the distinctive connexin coexpression patterns and relative levels in different cardiac tissues. Functional determinants of impulse propagation have emerged from electrophysiological experiments carried out on cell pairs. The static properties (channel number and conductance) limit the current flow between adjacent cardiomyocytes and thus set the basic conduction velocity. The dynamic properties (voltage-sensitive gating and kinetics of channels) are responsible for a modulation of the conduction velocity during propagated action potentials. The effect is moderate and depends on the type of Cx and channel. For homomeric-homotypic channels, the influence is small to medium; for homomeric-heterotypic channels, it is medium to strong. Since no data are currently available on heteromeric channels, their influence on impulse propagation is speculative. The modulation by gap junction channels is most prominent in tissues at the boundaries between cardiac tissues such as sinoatrial node-atrial muscle, atrioventricular node-His bundle, His bundle-bundle branch and Purkinje fibers-ventricular muscle. The data predict facilitation of orthodromic propagation.