Delayed K+ current and external K+ in single cardiac Purkinje cells.
The effect of external K+ on the delayed K+ current was investigated in rabbit single Purkinje cells. Whole cell voltage clamp and intracellular dialysis were used. At K+ concentrations less than 1 mM the kinetics of the delayed K+ current were not changed, but the conductance was markedly reduced. This effect was due to a direct change at an extracellular site and not due to secondary changes in intracellular Na+ or Ca2+ concentrations. A rise in intracellular Na+ or Ca2+ rather increased the delayed K+ current. The decrease in the delayed K+ current in low external K+ was absent when the experiments were done in Na+-free solution. It is concluded that external Na+ exerts an inhibitory effect on the conductance of the delayed K+ current.
Scamps
F
F
Laboratory of Physiology, University of Leuven, Campus Gasthuisberg, Belgium.
Carmeliet
E
E
D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000502:physiology; D004553:Electric Conductivity; D004594:Electrophysiology / Q000379:methods; D066298:In Vitro Techniques; D011188:Potassium / Q000494:pharmacology*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D011689:Purkinje Cells / Q000187:drug effects / Q000502:physiology*; D011817:Rabbits; D012964:Sodium / Q000502:physiology
D015221:Potassium Channels; D012964:Sodium; D011188:Potassium; D002118:Calcium