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Characteristics of early afterdepolarization in mouse atrial fibers
Abstract:
Early afterdepolarization (EAD) in mouse atrial fibers was investigated under the treatment with aconitine, 3.0 mmol/L K+, quinidine, ryanodine or Bay k 8644. All of these EADs possessed the following common characteristics: all the parameters of EAD showed cycle length-dependence; take-off potential of the first triggered burst played an important role in the generation of the other parameters; hyperpolarization of the triggered brust enhanced the end of EAD; and the second plateau response might be used as an indicator of the capability of EAD generation of myocardiac cell. All those EADs were inhibited or abolished by nifedipine, tetrodotoxin or lidocaine. Potassium channel activators, lemakalim, thalium ion, acetyl-choline or high potassium could also inhibit or abolish the EADs. It is suggested that the EADs induced by different agents may base on a common mechanism: all currents contributing to the plateau phase of the action potential play an important role in the generation of EAD.
Insights
Early afterdepolarizations (EADs) in mouse heart cells are influenced by various factors and can be controlled by specific drugs. These findings offer insights into cardiac electrophysiology and potential therapeutic targets.
Area of Science:
- Cardiac Electrophysiology
- Molecular Cardiology
- Pharmacology
Background:
- Early afterdepolarizations (EADs) are abnormal heart rhythms that can lead to serious arrhythmias.
- Understanding the mechanisms underlying EAD generation is crucial for developing effective antiarrhythmic therapies.
Purpose of the Study:
- To investigate the common characteristics and underlying mechanisms of EADs induced by various agents in mouse atrial fibers.
- To identify potential therapeutic targets for controlling EADs and preventing associated cardiac arrhythmias.
Main Methods:
- Induction of EADs in mouse atrial fibers using agents like aconitine, high potassium, quinidine, ryanodine, and Bay k 8644.
- Analysis of EAD parameters, including cycle length-dependence, take-off potential, and hyperpolarization effects.
- Assessment of the inhibitory effects of drugs such as nifedipine, tetrodotoxin, lidocaine, and potassium channel activators.
Main Results:
- EADs induced by different agents exhibited common characteristics, including cycle length-dependence and sensitivity to take-off potential and hyperpolarization.
- The second plateau response was identified as a potential indicator of EAD generation capability.
- Nifedipine, tetrodotoxin, lidocaine, and potassium channel activators effectively inhibited or abolished induced EADs.
Conclusions:
- EADs induced by diverse agents appear to share a common underlying mechanism involving currents active during the action potential plateau phase.
- Modulation of these plateau currents offers a promising strategy for controlling EADs and managing cardiac arrhythmias.
- The findings provide valuable insights into the electrophysiological basis of EADs and their pharmacological management.