Mode of action of pyrethroids.

Since pyrethroids are potent neuropoisons, their mechanism of action on the nervous system can best be studied by means of electrophysiological techniques. The nerve excitation occurs as a result of changes in nerve membrane permeabilities to sodium and potassium ions, and therefore any effect of pyrethroids can be interpreted in terms of such permeabilities. Detailed analyses of the action of allethrin on the giant axons of the cockroach, the crayfish, and the squid performed by means of intracellular microelectrode and voltage clamp methods have revealed the ionic basis of the action of allethrin on the nerve.