The location and properties of preganglionic vagal cardiomotor neurones in the rabbit

The origins of preganglionic vagal neurons which slow the heart in the rabbit have been examined with standard neurophysiological stimulation and recording techniques. The activity of 216 neurones projecting to the right cervical vagus nerve have been recorded in localized areas of the brain stem. T...

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Bibliographic Details
Published in:Pflügers Archiv 1982-11, Vol.395 (3), p.244-250
Main Authors: Jordan, D, Khalid, M E, Schneiderman, N, Spyer, K M
Format: Article
Language:English
Subjects:
Animals
Autonomic Fibers, Preganglionic - cytology
Heart Conduction System - cytology
Heart Conduction System - physiology
Medulla Oblongata - cytology
Neurons - cytology
Neurons - physiology
Neurons, Efferent - cytology
Rabbits
Synaptic Transmission
Vagus Nerve - cytology
Vagus Nerve - physiology
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Summary:The origins of preganglionic vagal neurons which slow the heart in the rabbit have been examined with standard neurophysiological stimulation and recording techniques. The activity of 216 neurones projecting to the right cervical vagus nerve have been recorded in localized areas of the brain stem. Thirty-six of these neurones were classified as cardiomotor neurones since they had properties similar to those described for such neurones in the cat. All had efferent axons in the range of B fibres. They could be synaptically activated by electrical stimulation of the ipsilateral aortic nerve which in the rabbit is solely barosensory. The majority of these neurones (70%) were spontaneously active and those which were normally silent could be made to fire by iontophoretic application of DL-homocysteic acid (an excitant amino acid). This spontaneous, or evoked, activity showed evidence of a pulse rhythm (of baroreceptor origin) and respiratory modulation (firing predominantly during expiration). In response to application of DL-homocysteic acid, the neuronal excitation was usually accompanied by a small but significant bradycardia. Histological examination showed that these neurones were located in both the dorsal vagal nucleus and the nucleus ambiguus.
ISSN:0031-6768
1432-2013
DOI:10.1007/BF00584817