The role of the medullary lateral tegmental field in the generation and baroreceptor reflex control of sympathetic nerve discharge in the cat.

Abstract

Data from experiments with single neuron recordings as well as central microinjections of N-methyl-D-aspartate (NMDA) and non-NMDA excitatory amino receptor antagonists that have led to a model of central sympathetic pathways that includes synaptic relays in the medullary lateral tegmental field (LTF) of the cat are summarized. Evidence is presented that (1) the LTF contains a population of tonically active sympathoexcitatory neurons that drive rostral ventrolateral medullary neurons, (2) blockade of non-NMDA receptors in the LTF significantly reduces basal levels of sympathetic nerve discharge (SND) and mean arterial pressure in baroreceptor-denervated cats, and (3) blockade of NMDA-mediated neurotransmission in the LTF prevents baroreceptor reflex control of SND. Thus, LTF neurons play an important role in the generation and baroreceptor reflex control of SND in the cat.