Kinetic analysis of the L-type calcium current in enzymatically dissociated ferret ventricular myocytes.
The L-type calcium current (ICa-L) was studied in single ferret ventricular myocytes using whole-cell recording with single patch pipettes. Voltage-clamp experiments were performed at room temperature with internal and external Na(+)- and K(+)-free Tyrode solutions in order to isolate ICa-L. For depolarizing steps eliciting small ICa-L the decay of the current is best described by one exponential. For depolarizing steps eliciting large ICa-L (i.e. between -10 and +30 mV), the decay of the current is best described by the sum of two exponentials with a calcium-dependent fast (Tf) time constant and a voltage-dependent slow (Ts) time constant. Experiments conducted with different external concentration of Ca2+ and Ba2+ suggested that the inactivation and the time course of reactivation of the current after a depolarizing pulse are dependent on calcium ions. This confirms previous observations in heart muscle and reveals the existence of a calcium-dependent regulation process of the L-type calcium current in enzymatically dissociated ventricular myocytes from ferret heart.
Bouron
A
A
Laboratory of General Physiology, URA CNRS n. 290, University of Poitiers, France.
Potreau
D
D
Raymond
G
G
D000818:Animals; D001464:Barium / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D004594:Electrophysiology; D005289:Ferrets; D006352:Heart Ventricles / Q000166:cytology / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008564:Membrane Potentials; D008954:Models, Biological; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*
D001464:Barium; D002118:Calcium