Mechanism of modulation of GABA-activated current by internal calcium in rat central neurons.

GABA-activated currents in Purkinje cells isolated from rat cerebellum were investigated. Increase of intracellular Ca2+ in the physiological range of concentrations caused a decrease in GABA-activated chloride currents. This effect resulted from a decrease of both the maximal values of GABA-activated currents and possibly from the affinity of GABAA receptors. Therefore, the mechanism of Ca2+ effect on GABAA receptors in central rat neurons differs from that in bullfrog sensory neurons.