title: Evidence that glutamic acid is the neurotransmitter of baroreceptor afferent terminating in the nucleus tractus solitarius (NTS).
abstract: The possibility that L-glutamic acid (L-Glu) might be the neurotransmitter of baroreceptor afferents terminating in the nucleus tractus solitarius (NTS) and affecting activity of the autonomic nervous system was tested using a variety of techniques. Effects on blood pressure and heart rate of microinjections of L-Glu and antagonists into the NTS supported this contention. Use of blocking agents was confirmatory. Biochemical studies provided evidence that the agent (glutamic acid) is synthesized, stored and reaccumulated in these nerve endings. Furthermore, it was shown that L-Glu is released from the NTS in vivo. Degeneration of afferent terminals due to removal of the nodose ganglia reduced L-Glu levels in the NTS. After discussion of this and additional evidence that L-Glu is the transmitter and a consideration of reasons for eliminating other possibilities (substance P, etc.) it was concluded that L-glutamic acid is the neurotransmitter of baroreceptor afferents.
mesh_terms: D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D001794:Blood Pressure; D001933:Brain Stem / Q000502:physiology; D005971:Glutamates / Q000502:physiology*; D018698:Glutamic Acid; D006339:Heart Rate; D008526:Medulla Oblongata / Q000502:physiology*; D011311:Pressoreceptors / Q000502:physiology*; D051381:Rats; D012018:Reflex / Q000502:physiology; D009435:Synaptic Transmission; D014630:Vagus Nerve / Q000502:physiology
chemical_list: D005971:Glutamates; D018698:Glutamic Acid