ELECTRICAL-STIMULATION OF THE VAGUS INCREASES EXTRACELLULAR GLUTAMATERECOVERED FROM THE NUCLEUS-TRACTUS-SOLITARII OF THE CAT BY IN-VIVO MICRODIALYSIS

Release of glutamate into the extracellular space of the cat nucleus t ractus solitarii (NTS) was measured by in vivo microdialysis and high performance liquid chromatography. Perfusion of the probe with 100 mm potassium increased glutamate release by 21 1 % (P < 0.00 1), while el ectrical stimulation of the cervical vagus increased release by 53 % ( P < 0.01). These results are compatible with the hypothesis that gluta mate is a neurotransmitter released by vagal afferent nerve terminals in the NTS.