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Results for “Sympathetic Fibers, Postganglionic”

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At least 19 recordsLinked to original sources
PubMed1982

Changes in unmyelinated fibers including sympathetic postganglionic fibers of a skin nerve after peripheral neuroma formation.

Conduction velocities of unmyelinated fibers and proportions of postganglionic fibers which can be activated from the lumbar sympathetic trunk were determined for the superficial peroneal nerve of the cat's hindlimb. The nerve was either left intact (4 control experiments) or cut and ligated peripherally 6-245 days before the experiments so that neuromata developed (15 experiments). Additionally, 3 control experiments were performed on the sural nerve. Our findings are that about 20-30% of all unmyelinated fibers in intact skin nerves are postganglionic sympathetic fibers. This percentage of postganglionic axons, which can be activated from the preganglionic side, decreases to 0-7% 100 days or more after the nerve section. In intact skin nerves the conduction velocity of the afferent unmyelinated fibers is greater (mean +/- 1 S.D.: 0.88 +/- 0.17 m/s) than that of postganglionic axons (0.69 +/- 0.14 m/s). The conduction velocities in both types of axons decrease by 25-30% in nerves with peripheral neuroma. This occurs largely during the first 15 days following the nerve section described.

Adrenergic Fibers↗
PubMed1981

Paravertebral origin of postganglionic sympathetic fibers in the major splanchnic and distal coeliac nerves as demonstrated by horseradish peroxidase (HRP) retrograde transport method.

A significant number of sympathetic neurons in the lower thoracic paravertebral ganglia (lateral chain ganglia) were retrogradely labeled when the central cut end of the ipsilateral major splanchnic nerve was exposed to horseradish peroxidase (HRP) in the cat. HRP-labeled perikarya were found in all ganglia of that region of the chain from which the splanchnic nerve has its origin but they are most numerous in the last thoracic paravertebral ganglion, that adjacent to the T13 segment of the cord. The number of HRP-positive cell diminished rapidly in more rostral ganglia. Labeled cell bodies of postganglionic splanchnic neurons in the paravertebral ganglia were fusiform to oval in shape with cell diameters averaging between 25 to 45 micrometer. These results demonstrate that the splanchnic nerve contains, in addition to visceral afferents and preganglionic sympathetic constituents, many postganglionic fibers with cell bodies in the paravertebral ganglia. These splanchnic postganglionic axons pass through the coeliac ganglion and continue into distal coeliac nerves.

Animals↗
PubMed1995

Properties of postganglionic sympathetic fibers isolated from the right recurrent laryngeal nerve.

The pattern of response of 45 single postganglionic sympathetic axons dissected from the right recurrent laryngeal nerve was examined in chloralose-anesthetized cats. Both vagoaortic nerves were cut, and both sinus nerves were left intact. Each neuron, based on the presence of cardiac and respiratory rhythmicities in its resting activity and reaction to systemic hypoxia (10% O2 in N2 for 2 min), was classified into one of three classes. Class I neurons (n = 29, 64%) were activated during systemic hypoxia and had a pronounced cardiac and inspiration-related rhythmicity in their resting activity. Class II neurons (n = 12,27%) were inhibited during systemic hypoxia, and their cardiac and respiratory rhythmicities were either negligible or totally absent. Class III neurons (n = 4,9%), similarly to class I, had a pronounced cardiac and inspiratory rhythmicity but were not affected by systemic hypoxia. The systemic hypoxia was always accompanied by an increase in blood pressure. We conclude that class I and possibly class III neurons innervate the arteries of upper airways. We also discuss the possibility that class II neurons are responsible for regulating the smooth muscles of upper airways.

Action Potentials↗
PubMed1980

[Hormonal nature of long-term reactions of cerebral vessels to stimulation of cervical postganglionic sympathetic fibers].

In anesthetized cats, single unilateral electric shock applied to the postganglionic cervical sympathetic pathway induced a decrease of cerebral flow for 45--90 min in parietal region by 21.7 +/- 0.9% in the gray matter and by 51.3 +/- 1.2% at the boundary of the gray matter. The systemic arterial pressure remained constant. The cerebral oedema occurred on the stimulated side. These reactions seem to be due to vasopressin participation.

Animals↗
PubMed1983

Concentration dependence of rapid axonal transport: a study of the transport kinetics of [35S]methionine-labeled protein in postganglionic sympathetic fibers of the bullfrog.

The kinetics of transport of radiolabeled proteins in sympathetic axons of the bullfrog sciatic nerve were examined after injection of [35S]methionine into the S9 sympathetic ganglion. Under resting conditions at 20 degrees C, the fastest moving material was carried distally at 5.7 +/- 0.3 mm/hr. Various manipulations of temperature in the proximal part of the nerve were used to alter the amount of protein transported into the distal region, which was always kept at 20 degrees C. The velocity in this test region was found to increase to over 9 mm/hr when material that had accumulated at a cold block for 4 hr was released by rewarming. This acceleration was transient, and base line velocity was regained after 2 hr. In order to increase the local concentration of transported protein by a second method, the proximal part of several nerves was warmed to 28 degrees C. Maximal transport velocity in the 20 degrees C test region rose to 6.2 +/- 0.12 mm/hr. To decrease the local concentration of transported protein, the proximal part of other nerves was cooled to 15 degrees C. Maximal transport velocity in the 20 degrees C test region fell to 4.7 +/- 0.7 mm/hr. We conclude that there is a small but real tendency for the velocity of rapid axonal transport in this neural system to be positively related to the availability of material suitable for transport.

Animals↗
PubMed1989

[Causalgia in the upper limbs following neck trauma: existence of widespread dysfunction of sympathetic postganglionic fibers].

The functions of autonomic nervous system were systematically evaluated in a case of causalgia in the upper limbs after neck trauma. A 14-year-old boy had had hard blow on his nucha in a rough fight. After one week, a sustained burning pain, swelling and skin color change developed in the left upper limb. These symptoms also appeared in the right upper limb after 6 weeks. The physical examinations disclosed edema, reddish moist skin, and atrophic nail in the upper limbs. The neurological examinations showed a radiating pain to the upper limbs caused by the neck movement or pressure on the supraclavicular fossae, weakness of the upper limbs and left lower limb, and loss of sensation in the 5th to 8th cervical and first thoracic dermatomal segments. Deep tendon reflexes were diminished in the upper limbs and exaggerated in the lower limbs. Neither Horner syndrome nor sphincter disturbance was observed. He was diagnosed as being the cervicothoracic radiculopathy and cervical myelopathy due to the mechanical force. The burning pain disappeared with oral administration of guanethidine. On the examinations of the autonomic functions, the sweating response to the thermal stimulation was absent above the 5th thoracic dermatomal segment. The sweating response to the intradermal acetylcholine was decreased in the second and third thoracic dermatomal segments. The systolic hypotension with increasing pulse rate occurred on standing. The reactive elevation of the blood pressure to the intravenous tyramine was absent. The excessive elevation of the systolic blood pressure was induced by the subcutaneous injection of epinephrine. These results indicated the dysfunction of the sympathetic postganglionic sudomotor and vasomotor fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Abnormalities of sympathetic innervation in the area of an injured peripheral nerve in a rat model of neuropathic pain.

Using the rat model that we have developed, a potential underlying mechanism for sympathetically maintained neuropathic pain (SMP) was explored. In rats showing neuropathic pain behaviors after a tight ligation of the L5 spinal nerve, putative sympathetic postganglionic fibers were examined in the injured spinal nerve and the dorsal root ganglion (DRG), using immunohistochemical staining with antibody against tyrosine hydroxylase (TH). In the neuropathic rats, there was an increase in the number of TH-immunolabeled fibers in the spinal nerve, and some DRG cells were surrounded by the labeled fibers. These abnormalities of sympathetic postganglionic innervation of the injured spinal nerve or the DRG may be a part of the mechanisms underlying the development of SMP.

Animals↗
PubMed1993

Electrophysiological study of relations between the dorsal nerve of the penis and the lumbar sympathetic chain in the rat.

Afferent sensory inputs from the penis are carried by the dorsal nerve of the penis (DNP) to the spinal cord. Sympathetic outflow involved in the control of the urogenital tract is partly conveyed by the lumbosacral sympathetic chain. Our aim was to search for a sympathetic component in the DNP and relations between DNP afferents and sympathetic fibers conveyed by the distal sympathetic chain in anesthetized adult male rats. Stimulation of the lumbar sympathetic chain at the L4-L5 level (LSC4-5) elicited an evoked discharge on the DNP. This discharge was abolished by cutting the sympathetic chain distal to the stimulation site. Ganglionic blockade with hexamethonium and various neural sections revealed the presence of sympathetic postganglionic fibers in the DNP, originating in the sympathetic chain. Stimulation of the DNP evoked a reflex discharge in the LSC. This reflex was spinally mediated since it was abolished by acute spinal cord transection at the L5 level. Acute spinalization at the T8 level significantly reduced the latency of the evoked response. We hypothesize that both spinal and supraspinal control exist over relations of the DNP afferents with sympathetic outflow to the pelvis. Increase in sympathetic tone elicited by activation of penile sensory fibers could play a role in regulation of sexual function.

Afferent Pathways↗