Single channel potassium currents of the anomalous rectifier

Abstract

The recording of single channel currents has revealed the discrete events underlying the conductance changes for the Na and delayed K currents of the action potential, as well as those underlying acetylcholine-evoked currents^1–5. The existence of similar discrete events has been suggested by noise analysis of the current termed anomalous K rectifier^6,7, in which a K conductance is increased by hyperpolarization or by an increased extracellular concentration of K ions⁸. I have now used the patch current recording technique to investigate the anomalous rectifier of the tunicate egg cell. The statistics of pulse-like events in the patch current were found to be consistent with the inactivation kinetics of the anomalous rectifier. The extrapolated zero-current potential of the pulse-like events was approximately equal to that of the total anomalous K current. The single channel conductance was 5.2 pS in 50 mM K solution.