Ion channel redox model.

Na(+)- and Ca2(+)-channel blockers behave as electron donors in reactions with excited dye radicals, while agonists of these channels behave as electron acceptors in the same reactions. The opposite redox characteristics of channel blockers and agonists may reflect their opposite action on the channels. The observed regularities of channel-modulator reactions with free radicals, as well as, the ability of many proteins to influence long-range electron transfer, are the basis for a model of channel function and regulation by various agents in which labile electrons in the channel-forming protein acts as electric field sensors.