Figure 1From: The synergistic action of imidacloprid and flumethrin and their release kinetics from collars applied for ectoparasite control in dogs and catsThe use dependent effect of flumethrin. Figure 1a illustrates the three states of the voltage-gated sodium channel (closed, open and inactivated). Flumethrin binds preferentially to the open state of the Na-channel and keeps the channel open as indicated by the experiment shown in Figure 1b: In this experiment, flumthrin is applied (10 μM, green bar) to an isolated insect nerve cell in the whole cell voltage clamp configuration (holding potential Vc = -100 mV, Na+ channels closed). During the experiment 20 short current pulses (downward arrows, every 1250 ms) were applied to change the holding potential from -100 mV to -10 mV to activate the voltage-gated Na channels (the thin downward lines reflect the Na currents induced by opening of the Na channels). Because flumethrin caused a downward change in the membrane current after Na+ channel opening only and not during the much longer resting phase, this experiment clearly demonstrated the use-dependent effect of flumethrin. (Figure 1a modified from: reference [33]).Back to article page