[Physiological characteristics of single K+ channel currents (Ik) in cerebellar cortical neurons of neonatal rat].

The characteristics of single K+ channels in cultured cerebellar granule neurons of neonatal rat were studied by the cell- attached and inside-out configurations of patch clamp technique. The results are as follows: the predominant conductance of single channel was 25PS, the currents amplitude, the mean open time and the open probability were dependent of membrane potential, the open time distribution histograms were fitted by two exponential components, the channel activity was not inactivated during 20 s period, independent of calcium and blocked by tetraethylammonium. These results indicated that the single channel was a delayed rectifier (Ik). It is suggested that the non-inactivating channel with conductance of 25pS which exists in the cerebellar granule cell might be a new subtype of Ik channel.