contributing to the elevated susceptibility to ventricular fibrillation

contributing to the elevated susceptibility to ventricular fibrillation

Sympathetic denervation is frequently observed in heart disease. To investigate the linkage of sympathetic denervation and cardiac arrhythmia, we developed a rat model of chemical sympathectomy by subcutaneous injections of 6-hydroxydopamine (6-OHDA).
We observed that sympathectomy (i) decreased cardiac sympathetic nerve density and norepinephrine level, (ii) reduced the protein expression of Kv4.2, Kv1.4, and Kv channel-interacting protein 2 (KChIP2), (iii) decreased current densities and delayed activation of I_to channels, (iv) reduced the phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and cAMP response element-binding protein (CREB), and (v) increased the severity of ventricular fibrillation induced by rapid pacing.
We conclude that chemical sympathectomy downregulates the expression of selective Kv channel subunits and decreases myocardial I_to channel activities, contributing to the elevated susceptibility to ventricular fibrillation.
Can. J. Physiol. Pharmacol. 86(10): 700–709 (2008)

Sterility following lumbar sympathectomy

Bacq (1931) found that bilateral lumbar sympathectomy in rabbits resulted in sterility with prolonged copulation and absence of orgasm.
J. Reprod. Fertil. (1964) 7, 113-122

Altered Cerebral Blood Flow following Sympathectomy

The subject has recently been studied by James, Millar&Purves who measured the cerebral vascular response to hypoxia with all nerves intact and following division or stimulation of the vagus and cervical sympathetic nerves. The effect of sympathectomy (...) is seen to consist of an elevation of both grey and white matter blood flow 40-50 per cent above control over the range of PaO2 tested, 35 to 440 mmHg. When the cervical sympathetic nerve as stimulated at constant frequency and intensity, cortical flow was reduced to control levels.

The Physiology of the Cerebral Circulation (Monographs of the Physiological Society) by M. J. Purves (Hardcover - May 31, 1972)

decrease in resting pulmonary resistance that follows thoracic thoracic sympathectomy

Diminished sympathetic constrictor discharge to pulmonary arterioles probably contributes to the lowering of resistance. No direct evidence for such an action has been presented, but the decrease in resting pulmonary resistance that follows thoracic thoracic sympathectomy shows that the potential for such a response exists. Whatever the mechanism, the net result is that pulmonary blood flow can be increased greatly without raising intravascular pressures to a degree that would encourage capillary transudation of fluid.

Cardiovascular physiology

By William R. Milnor

New York : Oxford University Press, 1990.

Sympathetic nervous system control of anti-influenza CD8+ T cell responses

Adoptive transfer experiments indicate that enhanced CD8⁺ responses do not result from permanent alterations in CD8⁺ T cell function in sympathectomized mice. Rather, additional findings suggest that the sympathetic nervous system tempers the capacity of antigen-presenting cells to activate naïve CD8⁺ T cells. We also show that antiviral CD8⁺ T cell responses are enhanced by administration of a β₂ (but not β₁ or α) adrenergic antagonist. These findings demonstrate a critical role for the sympathetic nervous system in limiting CD8⁺ T cell responses and indicate that CD8⁺ T cell responses may be altered in patients using β-blockers, one of the most widely prescribed classes of drugs.
PNAS March 31, 2009 vol. 106 no. 13

Following sympathectomy the basal t-PA activity in plasma was 70% less than controls

Following sympathectomy: (i) the basal t-PA activity in plasma was 70% less than controls (2.92 ± 1.96 versus 9.33 ± 1.72 IU/ml;P ≤ 0.001); (ii) the acute release from isolated vessels induced by bradykinin or phenylephrine was comparably reduced; and (iii) the greatest reductions occurred in densely innervated small vessel explants. The results provide new support for an autonomic regulation of neural t-PA release into the vessel wall matrix and blood of densely innervated thin-walled microvessels.

Blood Coagulation & Fibrinolysis:

September 2002 - Volume 13 - Issue 6 - pp 471-481

In another work on dogs, sympathectomy caused a state similar to atrophic rhinitis in man

Relationship Between the Vegetative Innervation and the Sensibility of the Nasal Mucosa
Z. Krajina; Z. Poljak
Acta Oto-Laryngologica, 1651-2251, Volume 79, Issue 3, 1975, Pages 172 – 175

Structural changes associated with parotid "degeneration secretion" after post-ganglionic sympathectomy

This loss of granules is considered to be due to sympathetic "degeneration secretion" caused by the release of noradrenaline from the degenerating adrenergic nerves between 12 and 24 hours after ganglionectomy. This is thought to be the first example of morphological change resulting from "degeneration activation" to be recorded microscopically.
Cell Tissue Res. 1975 Sep 16;162(1):1-12.

PMID: 1175216 [PubMed - indexed for MEDLINE]

Gray Hair and Sympathectomy: Report of a Case

LERNER
Arch Dermatol.1966; 93: 235-236.

acinar degranulation following sympathectomy

Chronic bilateral postganglionic sympathectomy (4-6 weeks duration) caused a drastic reduction in the capacity of the gland to secrete saliva in response to parasympathetic stimulation, reaching only one-third of that from normal animals. The initial output of amylase was greater than in normal animals but the total output was similar. The control unstimulated sympathectomized glands appeared similar morphologically to normal resting glands. However, on the parasympathetically stimulated side, besides the usual amount of acinar degranulation, there was also a conspicuous development of acinar vacuolation, not seen in the other groups of animals.
J. Physiol. November 15, 2008 586:5537-5547

Cervical sympathectomy inhibits axonal transport of gonadotropin-releasing hormone

To examine the effects of cervical sympathectomy on the transport of gonadotropin-releasing hormone (GnRH) between the hypothalamic neurons and the median eminence, 16 male rats were assigned into four groups: control (C), light (L), light-sympathectomy (LS), and light-colchicine (LC).

Considering the action of colchicine, which inhibits axonal transport, it is suggested that cervical sympathectomy also inhibits axonal transports of GnRH between the GnRH neurons and the median eminence during continuous exposure to light.
Journal of Anesthesia
Volume 10, Number 3 / September, 1996

Calcitonin gene-related peptide and substance P contribute to reduced blood pressure in sympathectomized rats

Am J Physiol Heart Circ Physiol 289: H1169-H1175, 2005.

Sympathectomized rats displayed reductions in blood pressure (BP) and atria norepinephrine levels, whereas NGF levels in the DRG, spleen, and ventricles were increased. Sympathectomy also enhanced CGRP and SP mRNA and peptide content in DRG. Administration of CGRP and SP receptor antagonists increased the BP in sympathectomized rats but not in the controls. Thus sympathectomy enhances sensory neuron CGRP and SP expression that contributes to the BP reduction.

Neurogenic and non-neurogenic inflammation in the rat paw following chemical sympathectomy

http://www.ncbi.nlm.nih.gov/pubmed/1723182?dopt=Abstract

Neuroscience. 1991;45(3):761-5.
Neonatal guanethidine sympathectomy caused an 86% depletion of noradrenaline in the paw skin and neurogenic plasma protein extravasation upon antidromic nerve stimulation was impaired. Sensory neuropeptides were unchanged in the skin after neonatal guanethidine and only calcitonin gene-related peptide content was increased in the spinal cord and sciatic nerves. The other observations (i.e. the sensitivity towards heat stimuli, the neurogenic mustard oil inflammation and the non-neurogenic carrageenan oedema) were similar to those observed after neonatal 6-hydroxydopamine treatment.

Sympathectomy exaggerates antihypertensive effect of vasopressin withdrawal

The results are consistent with the hypothesis that withdrawal of sympathetic activity is a contributing factor or a prerequisite condition for development of a WAP.(withdrawal-induced antihypertensive phenomenon)
AJP - Heart and Circulatory Physiology, Vol 268, Issue 1 1-H6, Copyright © 1995 by American Physiological Society

plasma levels of natriuretic peptides in response to sympathectomy

The occurrence of receptor binding sites for natriuretic peptides was examined by in vitro receptor autoradiography. In contrast to the marked occurrence of natriuretic peptide receptor binding sites seen in the ventricular endocardium of control rats, the sympathectomized rats exhibited a decreased number of binding sites for natriuretic peptides in the endocardium of both the right and left chambers. Interestingly, this was found in parallel with a significant decrease of systolic and diastolic blood pressure and increased plasma levels of pro-atrial natriuretic peptide in the treated group of rats. These findings, together with those in previous studies, give support to an idea that one part of the blood pressure-decreasing effects, seen in patients treated with β-adrenergic blockade, might be through a reduction of the natriuretic clearance receptor C, then giving rise to increased levels of atrial natriuretic peptide.

http://cat.inist.fr/?aModele=afficheN&cpsidt=17030448

Abolition of sympathetic skin responses following endoscopic thoracic sympathectomy

The recording of sympathetic skin responses (SSRs) is a simple, electrophysiological method to assess sympathetic nerve function. Within the last 10 years, SSRs have mainly been applied to delineate peripheral and central nervous system diseases, although the sympathetic nature of these responses was not fully documented, e.g., by a study of sympathectomy. We therefore recorded SSRs before and after 30 cases of endoscopic thoracic sympathectomy. The main indication was palmar hyperhidrosis, in which we found two types of SSR abnormalities. Most patients exhibited normal SSR waveforms but with increased amplitudes. The other patients exhibited abnormal SSRs which did not occur as single responses but as several consecutive waves.

Muscle & Nerve

Volume 19 Issue 5, Pages 581 - 586

Published Online: 7 Dec 1998

cervical sympathectomy resulted in a rapid degeneration in some of the cells in the sinuatrial and atrioventricular nodes

This study describes the ultrastructural changes in the sinuatrial and atrioventricular nodes of the heart of the monkey (Macaca fascicularis) after right cervical sympathectomy. Obvious changes in the nodal cells were seen one day after operation. Numerous glycogen particles grouped together to form electron-dense patches containing vacuoles in the cytoplasm. At three days after operation, intracellular organelles exhibited fragmentation and dissolution. By five and seven days after operation, the affected cells were vacuolated and some were swollen and appeared to have degenerated. Simultaneously, there was massive infiltration of macrophages were present nodal tissues. Axon profiles and terminals showing various degrees of degeneration were present in the vicinity of the nodal cells throughout the period of study.

J Anat. 1984 October; 139(Pt 3): 449–461.

Electrophysiology - effect on the heart

Chemical sympathectomy was obtained following intravenous injection of 50 mg·kg^–1 of 6-hydroxydopamine. Sympathectomised dogs presented significant increases in: basic sinus period, sino-atrial conduction time (SACT), AH and HV intervals of the His bundle electrogram, atrial functional (AFRP) and effective (AERP) refractory periods, atrio-ventricular node functional (AVNFRP) and effective (AVNERP) refractory periods, ventricular functional (VFRP) and effective (EVRP) refractory periods and atrial (AMAP) and ventricular (VMAP) monophasic action potential durations. Corrected sinus recovery time (CSRT) was not affected by chemical sympathectomy. Neither was the atrial ERP/MAP duration ratio. This new form of sympathectomy affects all the levels of the cardiac conduction system. Such results are in accordance with those obtained with surgical sympathectomy or the use of beta-blocking agents.

Cardiovascular Research 1982 16(9):524-529; doi:10.1093/cvr/16.9.524

Infra-stellate upper thoracic sympathectomy results in a relative bradycardia during exercise, irrespective of the operated side

Patients should be informed of the exercise bradycardia resulting from ISS.

Eur J Cardiothorac Surg 2001;20:1095-1100

Sympathectomy induces adrenergic excitability of cutaneous C-fiber nociceptors

Journal of Neurophysiology, Vol 75, Issue 1 514-517, Copyright © 1996 by APS

The induction of adrenergic excitability in CPMs by sympathectomy is suggested to be a counterpart to postsympathectomy neuralgia in human beings and a possible part of the mechanism leading to sympathetically related pain states.

The results provide new evidence about the change in atrial natriuretic peptide levels that occurs when sympathetic innervation is altered.

PMID: 9799658 [PubMed - indexed for MEDLINE]

J Mol Cell Cardiol. 1998 Oct;30(10):2047-57.

Neuroma following nerve injury/surgery

When a nerve is cut, the piece of nerve that is beyond the cut point eventually dies, however, its Schwann cells, the cells that encircle the nerve fibers remain for a much longer time. These Schwann cells secrete a chemical messenger known as nerve growth factor that tells the cut end of nerve where to grow back. So the cut end of nerve will send out multiple sprouts in the direction of the nerve growth factor, however, these sprouts do not go out in an orderly manner, instead they grow out in all directions and eventually cluster and form a knot of nerve fibers. This eventually leads to the formation of a TRUE neuroma or a END BULB or STUMP neuroma.

www.tarsaltunnelcenter.com/assets/recurrent.shtml