Synaptic transmission in thoracic autonomic ganglia of the dog

Afferent stimulation of one canine thoracic cardiopulmonary nerve can generate compound action potentials in another ipsilateral cardiopulmonary nerve. These compound action potentials persist after acute decentralization of the middle cervical ganglion, indicating that they result from neural activity in the middle cervical ganglion and thoracic nerves. Changing the frequency of stimulation can alter the compound action potentials, suggesting that temporal facilitation or inhibition occurs in this middle cervical ganglion preparation. The compound action potentials can be modified by stimulation of sympathetic preganglionic fibers and by hexamethonium, atropine, phentolamine, propranolol, and (or) manganese. It thus appears that afferent cardiopulmonary nerves can activate efferent cardiopulmonary nerves via synaptic mechanisms in the stellate and middle cervical ganglia. It also appears that these mechanisms involve adrenergic and cholinergic receptors and are influenced by preganglionic sympathetic fibers arising from the cord.

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Synaptic transmission in the chronically decentralized middle cervical and stellate ganglia of the dog

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y83-171 ◽

1983 ◽

Vol 61 (10) ◽

pp. 1149-1155 ◽

Cited By ~ 15

Author(s):

J. A. Armour

Keyword(s):

Central Nervous System ◽

Action Potentials ◽

Autonomic Nerves ◽

Autonomic Ganglia ◽

Afferent Nerves ◽

Stellate Ganglia ◽

Compound Action Potentials ◽

The Central Nervous System ◽

Compound Action ◽

Stimulation Of

Afferent stimulation of one thoracic cardiopulmonary nerve generated compound action potentials in the efferent axons of other ipsilateral cardiopulmonary nerves in dogs, 14 days after their thoracic autonomic ganglia had been decentralized. The compound action potentials were influenced by the frequency of activation and (in 5 of 12 dogs) by pharmacological autonomic blocking agents (hexamethonium, atropine, phentolamine, and propranolol). Moreover, they were abolished transiently when chymotrypsin was injected locally into the ganglia, and extendedly when manganese was injected. Thus, synapses that can be activated by stimulation of afferent nerves exist in chronically decentralized thoracic autonomic nerves and ganglia. It is proposed that regulation of the heart and lungs occurs in part via thoracic autonomic neural elements independent of the central nervous system.

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Compound action potentials of cat optic nerve produced by stimulation of optic tracts and of optic nerve

Experimental Neurology ◽

10.1016/0014-4886(67)90014-3 ◽

1967 ◽

Vol 19 (2) ◽

pp. 156-165 ◽

Cited By ~ 13

Author(s):

Rainer Spehlmann

Keyword(s):

Optic Nerve ◽

Action Potentials ◽

Compound Action Potentials ◽

Compound Action ◽

Stimulation Of

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Activity of in situ middle cervical ganglion neurons in dogs, using extracellular recording techniques

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y85-116 ◽

1985 ◽

Vol 63 (6) ◽

pp. 704-716 ◽

Cited By ~ 21

Author(s):

J. A. Armour

Keyword(s):

Neuronal Activity ◽

Action Potentials ◽

Vena Cava ◽

Extracellular Recording ◽

Cervical Ganglion ◽

Cervical Ganglia ◽

Ganglion Neurons ◽

Stimulation Of ◽

Recording Techniques

Neuronal activity in the in situ middle cervical ganglion of dogs was investigated using extracellular recording techniques. The recorded action potentials were frequently active during specific phases of the cardiac cycle, particularly during systole, and this activity persisted following acute decentralization of the ganglion. The activity of these action potentials was modified when systemic arterial pressure was altered by isoproterenol, noradrenaline, adrenaline, or partial occlusion of the aorta, whether in the intact or acutely decentralized preparation. These neurons were active between systolic pressures of 70 and 180 mmHg (1 mmHg = 133.322 Pa). Action potentials were frequently modified by mechanical distortion of the superior vena cava, ventricular epicardium, or adventitia of the aorta, whether the preparation was acutely decentralized or not. Seventy percent of these action potentials were unaffected by stimulation (1 ms, 4 V, 0.5 Hz) of a cardiopulmonary nerve and 27% were suppressed by such stimulation. Five of the neurons were activated by such stimulation. It is presumed that the latter neurons had axons in a cardiopulmonary nerve and most likely were efferent sympathetic postganglionic neurons. Sixty-three percent of these spontaneously active phase-locked units were modified by stimulation of a ramus or an ansa. It is postulated that some of the neurons in the middle cervical ganglia can be modified by afferent axons arising from receptors in thoracic organs, in particular from the great vessels and heart, whether in an intact or acutely decentralized preparation. The majority of these neurons are presumed not to be afferent neurons or efferent postganglionic neurons, as they are not activated directly by electrical stimulation of axons in cardiopulmonary nerves. Rather they are presumed to be interneurons. These results lend support to the thesis that considerable integration of neuronal activity related to thoracic cardiovascular dynamics occurs within the middle cervical ganglia of dogs.

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