A MECHANOSENSITIVE K-GATING KINETICS ON HUMAN AXONS BLOCKED BY GADOLINIUM IONS( CHANNEL WITH FAST)

Current recordings from single mechanosensitive potassium channels wer e obtained from cell-attached and excised patches of human axons. The channel showed an inwardly rectifying I-V relationship with a slope co nductance 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 th e closed state. The open probability of this channel increased as nega tive pressure was applied to the patch pipette. The pressure dependenc e of the open probability of the mechanosensitive K+ channel followed a sigmoid relationship. Gadolinium (0.5-1 mM) acted as a potent blocke r when applied to the intra- and extracellular side of the patch membr ane.