Effects of alpha- and theta-cypermethrin insecticide on transient outward potassium current in rat hippocampal CA3 neurons

The effects of two cypermethrin insecticides, alpha-cypermethrin and theta-cypermethrin on the transient outward potassium (IA) channels in freshly dissociated hippocampal CA3 neurons of rat, were studied using whole-cell patch clamp technique. The results indicate that alpha-cypermethrin increased the amplitude of IA and theta-cypermethrin decreased the amplitude of IA, and both of them shifted steady activation curve of IA towards negative potential. Theta-cypermethrin contributed in the inactivation of IA. Alpha-cypermethrin prolonged the time constants for the recovery from inactivation kinetics of IA. These results imply that transient outward potassium (IA) channels are the target of cypermethrin, which may explain the mechanism of toxical effects of cypermethrin on mammalian animals.