Related Experiment Videos
Action potential conduction between guinea pig ventricular cells can be modulated by calcium current
1Todd Franklin Cardiac Research Laboratory, Department of Pediatrics, Emory University, Atlanta, Georgia 30323.
The American Journal of Physiology
|November 1, 1992
Summary
Calcium current significantly impacts action potential conduction between coupled cardiac cells, especially at high resistance. Reducing calcium current increases repolarization and conduction delay, suggesting its crucial role in cell-to-cell electrical signaling.
Area of Science:
- Cardiovascular Physiology
- Electrophysiology
- Cell Biology
Background:
- Electrical coupling between cardiac cells is essential for coordinated heart function.
- Action potential (AP) propagation relies on ionic currents and intercellular resistance.
- The precise role of calcium current in AP conduction at high coupling resistance remains incompletely understood.
Purpose of the Study:
- To investigate the involvement of calcium current in generating the source current during AP conduction.
- To determine how reducing calcium current affects AP characteristics and conduction between coupled cells.
Main Methods:
- Utilized electrically coupled cell pairs with high intercellular resistance.
- Reduced calcium current using nifedipine (NIF), premature stimulation, and increased stimulation frequency.
- Measured ionic membrane current (Iion) and analyzed AP repolarization and conduction delay.
Main Results:
- Coupling cells caused Iion to become negative and large, supplying coupling current.
- Nifedipine decreased net negative Iion, accelerated early repolarization, and increased conduction delay.
- High coupling resistance decreased conduction, an effect exacerbated by NIF, prematurity, or high stimulation frequency.
Conclusions:
- Calcium current plays a significant role in supplying the coupling current during AP conduction at high intercellular resistance.
- Reduced calcium current leads to faster early repolarization and increased conduction delay between coupled cells.
- These findings highlight the importance of calcium current for reliable electrical signal propagation in the heart.