Role of medullary excitatory amino acid receptors in mediating the 10-Hz rhythm in sympathetic nerve discharge of cats

We tested the hypothesis that excitatory amino acid (EAA)-mediated transmission plays a role in generating the 10-Hz rhythm in sympathetic nerve discharge (SND) of baroreceptor-denervated, urethane-anesthetized cats. Microinjection of either an N-methyl-d-aspartate (NMDA) or non-NMDA receptor antagonist into any one of three medullary regions (lateral tegmental field, rostral, or caudal ventrolateral medulla) essentially eliminated the 10-Hz rhythm in inferior cardiac SND. We conclude that EAA receptors in the medulla are critical for generation of the 10-Hz rhythm.