Tefluthrin

OD-1 (C₃₀₈H₄₆₆N₉₀O₉₅S₈, GVRDAYIADDKNCVYTCAS-NGYCNTECTKNGAESGYCQWIGRYGNACWCIKLPDEVPIRIPG-KCR) was obtained from Tocris Cookson Ltd. (Bristol, UK); carbamazepine and tefluthrin were obtained from Sigma-Aldrich (St. Louis, MO, USA). Unless stated otherwise, the tissue culture media, horse serum, fetal bovine and calf serums, L-glutamine, and trypsin/EDTA were obtained from Invitrogen (Carlsbad, CA, USA). The stock solution of OD-1 was vigorously vortexed to ensure complete solubilization before the experiments were performed. All other chemicals, such as CsCl, CsOH, aspartic acid, and HEPES, were of the best available quality, most of which were of analytical grade.
The composition of the HEPES-buffered normal Tyrode’s solution was as follows (in mM): NaCl 136.5, KCl 5.4, CaCl₂ 1.8, MgCl₂ 0.53, glucose 5.5, and HEPES-NaOH buffer 5.5 (pH 7.4). To record action currents (ACs) or K⁺ currents, the recording pipettes were filled with the following solution (in mM): K-aspartate 130, KCl 20, KH₂PO₄ 1, MgCl₂ 1, EGTA 0.1, Na₂ATP 3, Na₂GTP 0.1, and HEPES-KOH buffer 5 (pH 7.2). To measure the Na⁺ currents, K⁺ ions inside the pipette solution were replaced with equimolar Cs⁺ ions, and the pH value of the solution was adjusted to 7.2 with CsOH. The pipette solution was filtered on the day of use with a 0.22-μm pore size syringe filter (Millipore, Burlington, MA, USA).

A total of 20 insecticides (representing diverse structures and known stereochemical composition) and three synergists were used (Fig 3): 1R-cis αS cypermethrin (100%, Bayer CropScience, Leverkusen, Germany), 1R-trans fenfluthrin (100%, Bayer CropScience), alpha-cypermethrin (99.5%, Chem Service, West Chester, PA, USA), bioallethrin (3.8% cis and 95.7% trans, Chem Service), bioresmethrin (99.5%, Chem Service), cis-permethrin (99.4%, Zeneca Ag products), cyfluthrin (99.2%, Chem Service), cyhalothrin (90.2%, ICI Americas), cypermethrin (44.8% cis and 53.9% trans, Chem Service), N-decarbomethoxylated JW062 (DCJW) (98%, DuPont), DDT (98%, Sigma-Aldrich, St. Louis, MO, USA), deltamethrin (99.5%, Chem Service), diethyl maleate (DEM) (97%, Sigma-Aldrich), etofenprox (96.3%, Mitsui Toatsu Chemicals, Tokyo Japan), flumethrin (100%, Bayer CropScience), permethrin (24% cis and 76% trans, Chem Service), piperonyl butoxide (PBO) (90%, Sigma-Aldrich), S,S,S-tributyl phosphorotrithioate (DEF) (97.3%, Chem Service), tau-fluvalinate (96%, Chem Service), tefluthrin (96%, Sigma-Aldrich), transfluthrin (99.5%, Chem Service), trans-permethrin (99%, FMC, Philadelphia, PA, USA).