ISSN:
1432-2013
Keywords:
Vagal preganglionic neurones
;
Heart rate
;
Nucleus ambiguus
;
Dorsal vagal nucleus
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The origins of preganglionic vagal neurones 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 fibers. 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 ofdl-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 ofdl-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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00584817
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