Spontaneous bioelectric activity of cultured purkinje cells during exposure to glutamate,glycine, and strychnine

The addition of glutamate to the bathing medium increased the average firing rate of cerebellar rat Purkinje cells in vitro. At concentrations lower than 10^?6 M, there was no deviation from controls in the firing pattern or rate that was detectable. At 10^?3 M glutamate, the amplitude of the action potentials was gradually decreased until all activity was abolished. The action of glutamate was rapid in onset and reversible. Glycine produced sustained depression of firing at concentrations higher than 10^?3 M. This inhibition was strychnine-insensitive and considered nonspecific. Strychnine, on the other hand, exerted an excitatory influence on Purkinje cells when applied at low concentrations (10^?8 to 10^?6 M). The firing became more irregular and complex discharges appeared. Higher concentrations of strychnine (>10^?5 M) inhibited the spontaneous activity. The effect of strychnine was partly reversible. The data suggest that low concentrations of strychnine lower the threshold for inputs at excitatory as well as inhibitory synapses.