FAST K-CHANNELS ARE MORE SENSITIVE TO RILUZOLE THAN SLOW K-CHANNELS IN MYELINATED NERVE-FIBER

The effects of 1-500 muM riluzole, a novel psychotropic agent, were studied on the nodal K current of isolated nerve fibres of the frog. When added to the external solution, the substance rapidly and reversibly inhibited slow, fast 1 and fast 2 K components of the tail K current. The concentrations of riluzole inducing half maximum reduction of slow, fast 1 and fast 2 K conductances were 413 muM, 24 muM and 21 muM respectively. It is concluded that the substance is about 20 times more effective in blocking fast than slow K channels.