Effect of Tubocurarine on Large-Conductance Cationic Channels in the Inner Nuclear Membrane of Purkinje Neurons of the Rat Cerebellum

摘要

Large-conductance cationic channels (LCCs) are present in the nuclear membranes of Purkinje neurons. Channels of this type are characterized by their selectivity with respect to monovalent cations, high unitary conductance, slow kinetics, and voltage dependence. The structural peculiarities, amino acid sequence in the molecules, and physiological role of these channels remain unknown. It is obvious that elucidation of functions of LCCs in the nuclear membranes depends on identification of a specific blocker of these channels. We carried out experiments using the patch-clamp technique and found a specific blocker of LCC channels. A well-known alkaloid, tubocurarine, was found to completely block the conductivity of LCC channels after application in concentrations of 1.0 mM or greater under conditions where the charge on the nuclear membrane is negative. At present, this compound is the only effective blocker of channels of the above-mentioned type.