Modulation by lanthanum ions of gamma-aminobutyric acid(A) receptors of rat cerebellum granule cells in culture: clues on their subunit composition

gamma -Aminobutyric acid (GABA) activated chloride currents were studied in rat cerebellum granule cells in culture by the whole cell patch-clamp tech nique. Both the peak and steady state currents were inhibited by 100 muM la nthanum. in the fi rst case, inhibition is due to an increase of the ECS, f or GABA. The inhibitory effect of lanthanum on the peak current at 3 muM GA BA increased with the cation concentration. A tendency towards the same beh avior was found also for the inhibition of the steady state current, at 3 m uM GABA, as a function of lanthanum concentration, although inhibition in t his case was lower. The comparison of the results with published data about the effects of lanthanum on recombinant GABAA receptors likely to occur in granule cells allows suggestions about the receptor types giving, respecti vely, the peak and the steady state component. (C) 2001 Published by Elsevi er Science Ireland Ltd.