Pentobarbital and brilliant green modulate the current response of recombinant rat kainate-type GluR6 receptor channels differentially.

Kainate-type receptor channels (GluR5-7, KA1,2) belong to the family of ionotropic glutamate receptor channels. In the present study we tested the interaction of two different drugs with GluR6 channels using outside-out patches from HEK cells transiently transfected with cDNA of GluR6 channels. Glutamate and the respective drugs were delivered by a system for ultrafast solution exchange. Application of a saturating concentration of 3 mM glutamate resulted in fast current transients with desensitization time constants between 3 and 10 ms. Addition of pentobarbital (>or=1 mM) to the 3 mM glutamate containing test-solution resulted in a significant decrease of the time constant of current decay without affecting the peak current amplitude. Brilliant green (>or=1 mM) had the opposite effect and led to an increase of the time constant of current decay after application of 3 mM glutamate. The pharmacological effects of both drugs were completely reversible. Additionally, a significant increase of the peak current amplitude and the time constant of deactivation in presence of brilliant green was observed. Summarizing our results, we could identify a further substance, brilliant green, interacting with GluR6 kainate-type receptor channels.