Inward-rectifying K+ channels in guinea-pig ventricular cells are partially inactivated by hyperpolarization, with open state probability decreasing from approximately 0.15 at -50 mV to 0.02 at -110 mV.
Inward currents through single K+ channels in isolated ventricular heart cells of the guinea-pig were recorded using the patch-clamp technique (Hamill, Marty, Neher, Sakmann the reason for this ambiguity is discussed. The channels are blocked by Cs+ or Ba2+. Cs+ (0.1 mM) caused frequent and short interruptions of the individual channel openings. Ba2+ (0.5 mM) also shortened the openings and in addition decreased the number of openings per burst. The results suggest that the inward-rectifying current IK1 in heart ventricular cells is partially inactivated by hyperpolarization. The inactivation could account for part of the time-dependent decrease in the whole-cell current previously ascribed to depletion of K+.
Sakmann et al. (Wed,) conducted a other in Inward-rectifying K+ currents. Voltage pulses and channel blockers (Cs+, Ba2+) was evaluated on Voltage-dependent gating properties and inactivation of inward-rectifying K+ channels. Inward-rectifying K+ channels in guinea-pig ventricular cells are partially inactivated by hyperpolarization, with open state probability decreasing from approximately 0.15 at -50 mV to 0.02 at -110 mV.