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Updated: Aug 29, 2026

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents
Published on: July 3, 2013
Reopening of L-type calcium channels in human ventricular myocytes during applied epicardial action potentials
1Department of Physiology, University Medical School of Debrecen, Debrecen, Hungary.
Aims:
Present study was performed to compare the dynamics of human L-type calcium current (ICa,L) flowing during rectangular voltage pulses, voltage ramps, and action potentials (APs) recorded from epicardiac and endocardiac canine ventricular cells.
Methods:
ICa,L was recorded in single myocytes isolated from undiseased human hearts using the whole cell voltage clamp technique.
Results:
The decay of ICa,L was monotonic when using rectangular pulses or endocardial APs as voltage commands, whereas the current became double-peaked (displaying a second rise and fall) during epicardial (EPI) APs or voltage ramps used to mimic EPI APs. These ICa,L profiles were associated with single-hooked and double-hooked phase-plane trajectories, respectively. No sustained current was observed during the AP commands. Kinetics of deactivation and recovery from inactivation of human ICa,L were determined using twin-pulse voltage protocols and voltage ramps, and the results were similar to those obtained previously in canine cells under identical experimental conditions.
Conclusions:
ICa,L can inactivate partially before and deactivate during the phase-1 repolarization of the epicardiac AP, and reopening of these channels seems to be associated with formation of the dome.
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