Tefluthrin modulates a novel anionic background conductance (I(AB)) in guinea-pig ventricular myocytes.
This report describes for the first time a novel anionic background current (I(AB)) identified in guinea-pig isolated ventricular myocytes. It also shows that I(AB) has both novel and differential pharmacology from other (cardiac) chloride currents. Using the whole-cell patch-clamp technique and external anion substitution, I(AB) was found to be outwardly rectifying and highly permeable to NO(-)(3), with a relative permeability sequence of NO(-)(3) > I(-) > Cl(-). I(AB) was not blocked by 50 microM DIDS, by hypertonic external solution, or by the nonselective protein kinase inhibitor H7-DHC. Exposure to the pyrethroid agent tefluthrin (10 microM) increased the current density of I(AB) significantly at positive voltages (P < 0.05), but had no significant effect on other cardiac chloride currents. We conclude that I(AB) possesses a distinct pharmacology and does not fall into the three major classes of cardiac chloride conductance commonly reported.
Borg
John J
JJ
Department of Pharmacology, University of Bristol, Bristol, BS8 1TD, United Kingdom.
Hancox
Jules C
JC
Spencer
C Ian
CI
Kozlowski
Roland Z
RZ
D000200:Action Potentials; D000818:Animals; D000838:Anions / Q000378:metabolism; D002478:Cells, Cultured; D018118:Chloride Channels / Q000502:physiology; D004553:Electric Conductivity; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D006352:Heart Ventricles / Q000166:cytology; D007306:Insecticides / Q000494:pharmacology*; D017136:Ion Transport / Q000187:drug effects; D018408:Patch-Clamp Techniques; D011722:Pyrethrins / Q000494:pharmacology*
D000838:Anions; D018118:Chloride Channels; D007306:Insecticides; D011722:Pyrethrins