EN
Insecticide permethrin causes paralysis of insects by modification of membrane sodium channel (VGNa). It binds to site 7 on VGNa which shows positive allosteric interaction with site 3 for a-toxin from the venom of the scorpion. Alpha toxin accelerates depolarizing effect of permethrin on insect (cockroach) isolated axon. We assumed that the interaction between toxin and permethrin will be observed also on the cockroach whole nervous chain activated by mechanostimulation of cercus. In toxin presence the activity of chain observed after permethrin was higher than after permethrin alone, decreased slower and often salves of spontaneus discharges appeared. Such results correspond well to observations performed on locomotor activity of the cockroach. Alpha toxin accelerated insect paralysis induced by permethrin.