title: Concentration-dependent accumulation of [3H]-deltamethrin in sodium channel Nav1.2/beta1 expressing Xenopus laevis oocytes.
abstract: Disruption of neuronal voltage-sensitive sodium channels (VSSCs) by pyrethroid insecticides such as deltamethrin (DLT) has been widely studied using Xenopus laevis oocytes transfected with VSSC. However, the extent of pyrethroid accumulation in VSSC-expressing oocytes is unknown. Therefore, accumulation of [(3)H]-DLT in non-transfected, sham (water)-transfected and VSSC (Na(v)1.2+beta(1))-transfected oocytes after a 1h exposure was measured using liquid scintillation counting. Successful transfection of Na(v)1.2+beta(1) VSSCs in X. laevis oocytes was confirmed by two-electrode voltage-clamp; inward, tetrodotoxin (TTX)-sensitive currents were obtained in 98% of all oocytes examined (n=60 in nine experiments). DLT (1.0 microM) induced tail currents in all VSSC-transfected oocytes; TTX also blocked these DLT-induced tail currents. In 0.1 microM DLT solution, non-transfected oocytes accumulated 0.098+/-0.01 ppm [(3)H]-DLT, sham-transfected oocytes accumulated 0.06+/-0.01 ppm DLT, and VSSC-transfected oocytes accumulated 0.050+/-0.009 ppm DLT. In 1.0 microM DLT solution, non-transfected oocytes accumulated 0.62+/-0.08 ppm DLT, sham-transfected oocytes accumulated 0.60+/-0.09 ppm DLT, and VSSC-transfected oocytes accumulated 0.51+/-0.07 ppm DLT. There was a significant difference in DLT accumulation between VSSC-transfected oocytes and non-transfected controls, where the transfected oocytes consistently had less accumulation.
authors.affiliation: North Carolina State University, Raleigh, NC 27695, USA.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Watkins
authors.forename: Connie A
authors.initials: CA
authors.lastname: Meacham
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Crofton
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Shafer
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D007306:Insecticides / Q000378:metabolism; D015640:Ion Channel Gating / Q000187:drug effects; D009570:Nitriles / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism*; D021122:Protein Subunits; D011722:Pyrethrins / Q000378:metabolism*; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D007306:Insecticides; D009570:Nitriles; D021122:Protein Subunits; D011722:Pyrethrins; D015222:Sodium Channels; C017180:decamethrin