Does lindane (gamma-hexachlorocyclohexane) increase the rapid delayed rectifier outward K+ current (IKr) in frog atrial myocytes?
1 Laboratoire d'Optique et Biosciences, Unité INSERM 451, UMR CNRS 7645, Ecole Polytechnique-ENSTA, F-91128 Palaiseau Cedex, France
2 Laboratoire de Toxicologie, Faculté de Pharmacie, Route du Rhin, 67400 Illkirch, France
BMC Pharmacology 2002, 2:15 doi:10.1186/1471-2210-2-15Published: 10 July 2002
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.
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.
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.