EFFECTS OF INHIBITORY AMINO-ACIDS ON THE FREQUENCY COMPONENTS IN SYMPATHETIC-NERVE DISCHARGE

The effects of the GABA antagonist picrotoxin and the glycine antagoni st strychnine on the frequency components in sympathetic inferior card iac nerve activity were observed. Picrotoxin (0.03-1.0 mg/kg) increase d power in the 10-Hz component of sympathetic activity and produced a dramatic shift in the rhythm to higher frequencies. Only small changes were noted in the 2- to 6-Hz component. Strychnine produced a small g eneralized increase in power in both frequency bands in sympathetic ac tivity. These data suggest that GABA may play an important role in the generation and maintenance of the 10-Hz rhythm in sympathetic activit y while glycine likely inhibits activity at a site of convergence of t he two rhythms in sympathetic activity.