A Horseradish Peroxidase Study of Vagal Motoneurones With Axons in Cardiac and Pulmonary Branches of the Cat and Dog

Bennett, JA; Kidd, C.; Latif, A. B.; McWilliam, P. N.

doi:10.1113/expphysiol.1981.sp002541

Cited by 53 publications

(38 citation statements)

References 24 publications

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“…It is generally accepted (La Vail & La Vail, 1974;Ellison & Clarke, 1975;Schramm, Adair, Stribling & Gray, 1975;Kristensson, 1978;Bennett et al 1981) that retrograde transport of horseradish peroxidase occurs at rates faster than 3-5 mm.h-1. The maximum transport distances involved in our experiments were 4 cm and 2 cm for the dog and cat respectively and even with the shortest elapsed time neurones much further rostral and caudal to those observed could have been labelled.…”

Section: Discussionmentioning

confidence: 99%

“…Sections were incubated for the demonstration of horseradish peroxidase labelled cells by a modified p-phenylenediamine pyrocatechol technique (Hanker, Yates, Metz & Rustioni, 1977;Bennett, Kidd, Latif & McWilliam, 1981) or by the tetramethyl benzidine method (Mesulam, 1978). They were air dried onto slides, cleared and mounted for examination using bright-and dark-field light microscopy.…”

Section: Methodsmentioning

confidence: 99%

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The Location and Characteristics of Sympathetic Preganglionic Neurones in the Lower Thoracic Spinal Cord of Dog and Cat

Bennett¹,

McWilliam²,

Goodchild

et al. 1986

Exp Physiol

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SUMMARYThe retrograde transport of horseradish peroxidase from a white ramus communicans has been used to define the precise segmental location of sympathetic preganglionic cell bodies in the spinal cord of the cat and dog. All labelled cells were found ipsilaterally and were confined to the spinal cord segment from which the ramus originated. Most lay in the intermediolateral cell column and the immediately adjacent white matter, though others were scattered in more medial areas of the grey matter. We suggest that the observed distribution of sympathetic preganglionic neurones, the orientation of their processes and the paths taken by their axons are a direct result of cell migration during the embryological development of the spinal cord.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

The Location and Characteristics of Sympathetic Preganglionic Neurones in the Lower Thoracic Spinal Cord of Dog and Cat

Bennett¹,

McWilliam²,

Goodchild

et al. 1986

Exp Physiol

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“…Ciriello & Calaresu (1979, however, claim a segregation of c.v.m.s, first, on the basis of location (dorsal vagal nucleus and nucleus ambiguus) and, secondly, as to whether they receive only one or convergent excitatory inputs from both sinus and aortic nerves. We do not eliminate the possibility of c.v.m.s being found on occasions in the dorsal vagal nucleus in the cat although we believe that the majority are located in the nucleus ambiguus (see also Bennett et al 1981) but whenever tested these c.v.m.s were shown to receive convergent inputs from both the sinus and aortic nerves. A segregation on the basis of input has also been challenged in experiments on rats (Nosaka, Yasunaga & Tamai, 1982).…”

Section: P Gilbey and Othersmentioning

confidence: 99%

Synaptic mechanisms involved in the inspiratory modulation of vagal cardio‐inhibitory neurones in the cat.

Gilbey¹,

Jordan²,

Richter³

et al. 1984

The Journal of Physiology

241

181

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SUMMARY1. The respiratory modulation of the activity of vagal cardio-inhibitory neurones of the nucleus ambiguus of the cat has been investigated by electrophysiological and neuropharmacological techniques.2. All twenty-four vagal efferent neurones studied had axons with conduction velocities indicative of B fibres and projected to the right cardiac branches of the vagus. Their spontaneous or DL-homocysteic acid (DLH)-evoked activity showed a marked reduction during the phase of inspiration and all showed signs of receiving a baroreceptor input.3. Ionophoretic application of DLH always excited cardiac vagal motoneurones (c.v.m.s). Application of acetylcholine to these same cells provoked a decrease in firing rate in twelve of the fifteen neurones tested. In ten of these twelve cells simultaneous application of atropine antagonized the effect of acetylcholine. Atropine applied alone enhanced neuronal firing, particularly in inspiration.4. Stable intracellular recordings have been made from two c.v.m.s. These were inhibited during inspiration. Input resistance fell markedly during inspiration and injection of chloride reversed this wave of hyperpolarization to a wave of depolarization indicating that this resulted from chloride-mediated inhibitory post-synaptic potentials (i.p.s.p.s).5. These c.v.m.s were activated during Stage I expiration, and showed a weak and variable wave of inhibition in Stage II expiration.6. Pulse-rhythmic depolarizing potentials were reduced in their amplitudes during the periods of decreased neurone input resistance.7. It is concluded that c.v.m.s receive an excitatory input during post-inspiration and a powerful inhibitory synaptic input during inspiration. The implications of these observations for the physiology of cardiorespiratory reflexes are discussed.

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“…The present results are not inconsistent with such a hypothesis. However, it was suggested that the pulmonary C fibre-evoked bradyeardia could involve vagal nonmyelinated preganglionic fibres with their cells in the dorsal vagal motor nucleus of the cat (Bennett et al 1981;Donoghue, Fox, Kidd & Koley, 1981;Bennett, Ford, Kidd & McWilliam, 1984;Jordan, Spyer, Withington-Wray & Wood, 1986). These neurones are cardioinhibitory in function (Woolley, McWilliam, Ford & Clarke, 1987) and can be activated synaptically by electrical stimulation of non-myelinated pulmonary vagal afferents (Bennett, Goodehild, Kidd & MeWilliam, 1985) but not by lung inflation (Bennett et al 1984).…”

Section: Possible Mechanisms Of Respiratory Modulationmentioning

confidence: 99%

Some reflex cardioinhibitory responses in the cat and their modulation by central inspiratory neuronal activity.

Daly

1991

The Journal of Physiology

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SUMMARY1. Cats were anaesthetized with a mixture of chloralose and urethane, and were artificially ventilated.2. An open pneumothorax was provided by two large-bore tubes which were sealed in the sixth intercostal space on each side. They were connected to a Fleisch pneumotachograph. Phasic changes in central inspiratory neuronal activity were measured quantitatively as changes in the volume of the pneumothorax during temporary interruption of artificial respiration, the volume of the lungs being held constant at their end-expiratory level. In this way the activity of slowly adapting pulmonary stretch receptors was maintained constant.3. Reflex cardioinhibitory responses were elicited by stimulation of (a) the carotid body chemoreceptors by intracarotid injections of cyanide; (b) the arterial baroreflex by controlled elevations of the blood pressure; (c) cardiac receptors by left atrial injections of veratridine; and (d) pulmonary C fibres (including J receptors) by right atrial injections of phenylbiguanide.4. The effects of central inspiratory neuronal activity on pulse interval were assessed by comparing the values observed during the inspiratory and expiratory phases of the respiratory cycle in the control state and during stimulation of each cardiovascular receptor group.5. The carotid chemoreceptor-induced bradycardia measured during the expiratory phase of respiration was reduced during inspiration to a value of about 15 % of control. The central inspiratory drive was less effective in altering the reflex responses from the arterial baroreceptors and cardiac receptors, the corresponding values being 42 and 51 % respectively.6. In contrast, the bradycardia evoked by pulmonary C fibre stimulation was not significantly affected by the central inspiratory drive.7. The differential nature of the modulation by the central inspiratory drive occurred independently of the integrity of the sympathetic nerve supply to the heart indicating that the cardiac efferents involved were largely fibres in the vagus nerves.8. The possible explanation of these results in terms of central mechanisms is discussed. MS 8872M. DE B. DALY

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A Horseradish Peroxidase Study of Vagal Motoneurones With Axons in Cardiac and Pulmonary Branches of the Cat and Dog

Cited by 53 publications

References 24 publications

The Location and Characteristics of Sympathetic Preganglionic Neurones in the Lower Thoracic Spinal Cord of Dog and Cat

The Location and Characteristics of Sympathetic Preganglionic Neurones in the Lower Thoracic Spinal Cord of Dog and Cat

Synaptic mechanisms involved in the inspiratory modulation of vagal cardio‐inhibitory neurones in the cat.

Some reflex cardioinhibitory responses in the cat and their modulation by central inspiratory neuronal activity.

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