AJP - Cell Physiology, Vol 257, Issue 6 C1086-C1092, Copyright © 1989 by American Physiological Society
Delayed K+ current and external K+ in single cardiac Purkinje cells
F. Scamps and E. Carmeliet
Laboratory of Physiology, University of Leuven, Campus Gasthuisberg, Belgium.
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.
