The large-conductance ion channels in the nuclear envelope of central neurons

Patch-clamp recording from the nuclear envelope of a variety of cells has revealed the presence of large-conductance ion channels. It has been argued that these channels are the channels of the nuclear pore complex for passive nucleo-cytoplasmic diffusion. Here we studied spontaneously active large-conductance ion channels in the nuclear envelope of cerebellar Purkinje neurons. These channels were selective for small monovalent cations and demonstrated clear voltage dependence. The channels recorded from the outer nuclear membrane were inhibited by positive potentials whereas the channels from the inner nuclear membrane were inhibited by negative potentials in the patch pipette. These data are compatible with the localization of the channels to the nuclear membrane. We conclude that these channels are not a part of the nuclear pore complex but provide a route for exchange of monovalent cations between the perinuclear space and the cytoplasm and the nucleoplasm.