Does lindane (gamma-hexachlorocyclohexane) increase the rapid delayed rectifier outward K+ current (IKr) in frog atrial myocytes?
BACKGROUND
The effects of lindane, a gamma-isomer of hexachlorocyclohexane, were studied on transmembrane potentials and currents of frog atrial heart muscle using intracellular microelectrodes and the whole cell voltage-clamp technique.


RESULTS
Lindane (0.34 microM to 6.8 microM) dose-dependently shortened the action potential duration (APD). Under voltage-clamp conditions, lindane (1.7 microM) increased the amplitude of the outward current (Iout) which developed in Ringer solution containing TTX (0.6 microM), Cd2+ (1 mM) and TEA (10 mM). The lindane-increased Iout was not sensitive to Sr2+ (5 mM). It was blocked by subsequent addition of quinidine (0.5 mM) or E-4031 (1 microM). E-4031 lengthened the APD; it prevented or blocked the lindane-induced APD shortening.


CONCLUSIONS
In conclusion, our data revealed that lindane increased the quinidine and E-4031-sensitive rapid delayed outward K+ current which contributed to the AP repolarization in frog atrial muscle.
Sauviat
Martin-Pierre
MP
Laboratoire d'Optique et Biosciences, Unité INSERM 451, UMR CNRS 7645, Ecole Polytechnique-ENSTA, F-91128 Palaiseau Cedex, France. martin-pierre.sauviat@polytechnique.fr
Colas
Anthony
A
Pages
Nicole
N
D000200:Action Potentials / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D051668:Delayed Rectifier Potassium Channels; D004594:Electrophysiology; D006325:Heart Atria / Q000166:cytology*; D001556:Hexachlorocyclohexane / Q000494:pharmacology*; D009206:Myocardium / Q000166:cytology; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D010880:Piperidines / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D015221:Potassium Channels / Q000502:physiology*; D024642:Potassium Channels, Voltage-Gated; D011725:Pyridines / Q000494:pharmacology; D011802:Quinidine / Q000494:pharmacology; D011898:Ranidae
D000889:Anti-Arrhythmia Agents; D051668:Delayed Rectifier Potassium Channels; D010880:Piperidines; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D011725:Pyridines; C063968:E 4031; D001556:Hexachlorocyclohexane; D011802:Quinidine