Functional properties of sodium channels do not depend on the cytoskeleton integrity.

ABSTRACT

Several observations suggest an interaction of the sodium channel alpha-subunit with the cytoskeletal structures. However, there is a wide variability in the results of experiments of heterologous expression in Xenopus oocytes and studies on mammalian cells are sometimes contradictory. In general, there has been no direct demonstration that ad hoc large perturbations of the cytoskeleton modify the intrinsic properties of the sodium channels expressed endogenously or heterologously in plasma membranes. We have studied in CHO cells transfected with the rat muscle sodium channel alpha-subunit the effects of two substances expected to produce drastic perturbations of the cytoskeletal structure Cytochalasin-D, which depolymerizes microfilaments, and Colchicine, which inhibits the microtubules polymerization. We observed no significant differences in the voltage dependence, kinetic parameters and surface density of the expressed sodium channels after treatment of the cells with these substances. We conclude that the two known main components of the cytoskeleton do not interfere directly with the sodium channel function or with the heterologous expression of channels in the cell membrane.