Block of gating currents by ultraviolet radiation in the membrane of myelinated nerve.

The effect of ultraviolet radiation on the asymmetrical displacement currents in the membrane of the node of Ranvier was measured and compared with the ultraviolet blocking of the sodium current. Ultraviolet radiation irreversibly reduced the peak sodium current and the charge displaced during a depolarizing test pulse, the relative reduction being independent of potential. The ratio of the ultraviolet sensitivities of the sodium and the asymmetrical displacement currents is 2.3+/- 0.2. This result suggests two independent identical gating particles per sodium channel in the membrane of myelinated nerve.