Effect of deltamethrin on acetylcholine-operated ionic channels in identified Helix pomatia L. neurons
Kiss, T. | Osipenko, O.N.
The main action of pyrethroids is to slow the gating kinetics of the Na channel of the axon and soma. However, it was also found that pyrethroids may affect the neurotransmission as well, acting postsynaptically. It can be proposed, therefore, that pyrethroids may have their target at the synaptic site in addition to the axonal or somal Na channels. The aim of the present study was to examine the effect of deltamethrin on acetylcholine (ACh) receptors of snail neurons using a two-microelectrode voltage clamp. Ionophoretic application of ACh on the soma of identified Helix neurons produced inward current of which amplitude was dependent on the holding potential. Deltamethrin (1-100 micromoles) depressed the ACh-induced current in a concentration-dependent manner. The I-V curves, both in control and in deltamethrin-containing saline, were linear in the potential range of -100 and -25 mV. The reversal potential was unchanged. The data suggest a monomolecular binding of deltamethrin to the ACh-activated channel with a KD of 50 micromoles. Deltamethrin increased the time of recovery from ACh desensitization. It can be concluded, therefore, that deltamethrin may contribute to its toxic effect by affecting the function of the ACh-receptors, although this effect could be secondary.
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