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Microelectrode Array Recording of Sinoatrial Node Firing Rate to Identify Intrinsic Cardiac Pacemaking Defects in Mice
Published on: July 5, 2021
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Characterization and influence of cardiac background sodium current in the atrioventricular node
Hongwei Cheng1, Jue Li2, Andrew F James1
1School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, UK.
Journal of Molecular and Cellular Cardiology
|May 2, 2016
Summary
The inward sodium current (IB,Na) in the atrioventricular node (AVN) was investigated. Blocking IB,Na stopped AVN cell activity and slowed conduction, revealing its crucial role in heart rhythm.
Area of Science:
- Cardiovascular Physiology
- Cardiac Electrophysiology
- Ion Channel Function
Background:
- The inward sodium current (IB,Na) is critical for cardiac pacemaking but remains under-investigated.
- Its role in the atrioventricular node (AVN), the heart's secondary pacemaker, is largely unknown.
Purpose of the Study:
- To characterize the properties of IB,Na in AVN cells.
- To determine the physiological role of IB,Na in AVN function and cardiac conduction.
Main Methods:
- Isolation of myocytes from rabbit and mouse AVN.
- Whole-cell patch-clamp electrophysiology with monovalent ion substitution.
- Computer modeling to simulate the physiological impact of IB,Na.
Main Results:
- An inward IB,Na was identified in AVN cells, dependent on extracellular sodium concentration.
- IB,Na is conducted by low-conductance, non-selective cation channels permeable to various monovalent cations.
- Inhibition of IB,Na in simulations arrested spontaneous AVN activity and reduced conduction velocity by approximately 20%.
Conclusions:
- IB,Na is a significant contributor to AVN electrical activity.
- These findings highlight IB,Na as a potential target for modulating heart rhythm and conduction.
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