A mechanosensitive K+ channel with fast-gating kinetics on human axons blocked by gadolinium ions.

Current recordings from single mechanosensitive potassium channels were obtained from cell-attached and excised patches of human axons. The channel showed an inwardly rectifying I-V relationship with a slope conductance of 52 pS at negative potentials (symmetrical high potassium solution). The fast-gating kinetics of the channel were best described by one time constant for the open state and two time constants for the closed state. The open probability of this channel increased as negative pressure was applied to the patch pipette. The pressure dependence of the open probability of the mechanosensitive K+ channel followed a sigmoid relationship. Gadolinium (0.5-1 mM) acted as a potent blocker when applied to the intra- and extracellular side of the patch membrane.