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PubMed2001

Morphological aspects of rabbit masseter muscle after cervical sympathectomy.

The objective of this paper was to study the effect of sympathetic innervation on morphological and histochemical aspects of skeletal muscle tissue. Rabbit masseter muscle was studied using histochemical and immunohistochemical methods for periods of up to 18 months post-sympathectomy. The morphological and enzymatic characteristics of control masseter muscles were similar on both the left and right sides. The main features were muscle fibres with a mosaic pattern and a predominance of type IIa fibres, followed by type I. Type IIb fibres showed very low frequency. Sympathectomized animals showed varying degrees of metabolic and morphological alterations, especially 18 months after sympathectomy. The first five groups showed a higher frequency of type I fibres, whilst the oldest group showed a higher frequency of type IIb fibres. In the oldest group, a significant variation in fibre diameter was observed. Many fibres showed small diameter, atrophy, hypertrophy, splitting, and necrosis. Areas with fibrosis were observed. Thus cervical sympathectomy induced morphological alterations in the masseter muscles. These alterations were, in part, similar to both denervation and myopathy. These findings indicate that sympathetic innervation contributes to the maintenance of the morphological and metabolic features of masseter muscle fibres.

Adipose Tissue↗
PubMed1975

A comparison of the supraclavicular and axillary approaches to upper thoracic sympathectomy.

Twenty-nine upper dorsal sympathectomies have been carried out in 18 patients and a comparison made of the supraclavicular with the axillary approach to the upper thoracic sympathetic chain. Thirteen of these operations were carried out for essential hyperhidrosis, 15 for ischaemia in the hand and one for post-traumatic pain syndrome. Fourteen sympathectomies were carried out through the axilla and 15 through the supraclavicular approach. Post-operative pain was felt to be somewhat more severe when the axillary approach was used, but other complications were infrequent and hospital stay was slightly shorter in the axillary group. The axillary approach was felt to offer superior exposure, the capability for wider sympathetic excision, good cosmetic results, avoidance of Horner's syndrome and low morbidity. In the absence of lung disease or the need for a direct exploration of the root of the neck, the axillary approach is to be preferred for upper dorsal sympathectomy.

Adult↗
PubMed1994

The preventive role of chemical sympathectomy on contralateral testicular hypoxic parameters encountered during unilateral testicular torsion.

OBJECTIVE: To evaluate the effect of chemical sympathectomy on lactic acid and hypoxanthine concentrations in both testes during unilateral testicular torsion in a rat experimental model. MATERIALS AND METHODS: Four groups, comprising 10 rats each, were studied. Group I was the control group, Group II rats received a placebo and underwent unilateral testicular torsion, Groups III and IV received guanethidine monosulphate and 6-OH-dopamine hydrobromide respectively, and underwent unilateral testicular torsion. The levels of lactic acid and hypoxanthine in both testes were measured. RESULTS: In rats in Group II the levels of lactic acid and hypoxanthine in both testes were significantly elevated when compared to the control group. In the groups of rats that had undergone chemical sympathectomy, the levels of lactic acid and hypoxanthine were significantly decreased in the contralateral testes compared to rats in Groups I and II. CONCLUSION: Chemical sympathectomy prevents the elevation of lactic acid and hypoxanthine levels in the contralateral testis of rats with unilateral testicular torsion. Therefore, we conclude that contralateral testicular damage during unilateral testicular torsion may result through a reflex activating sympathetic system.

Animals↗
PubMed1986

A physiological basis for subclassifying beta-adrenoceptors examined by chemical sympathectomy of guinea-pigs.

Chemical sympathectomy of guinea-pigs was induced by chronic pretreatment with 6-hydroxydopamine over a 20 day period. Control animals were sham injected with vehicle at the same times. Isolated tissues were removed from the animals and beta-adrenoceptor sensitivity assessed from cumulative concentration-response curves for isoprenaline, followed after wash-out by a partial agonist (salbutamol, ritodrine or prenalterol). The following responses were measured: increases in force and rate of contraction of left and right atria respectively, inhibition of carbachol-induced ileal contractions, relaxation of intrinsic tone of lung strips and tracheal spirals, inhibition of contractions of vas deferens and soleus muscle induced by field stimulation. Left and right atria and ileum from 6-hydroxydopamine-pretreated guinea-pigs exhibited supersensitivity to beta-adrenoceptor stimulation. This was measured as a leftwards shift of the concentration-response curve for isoprenaline and as an elevation of the partial agonist maximum response (relative to isoprenaline), when compared with tissues from sham-injected controls. The supersensitivity was assumed to be due to the loss of endogenous neurotransmitter release by chemical sympathectomy and specific for the beta-adrenoceptor. In contrast, lung strips, vas deferens and soleus muscle were not supersensitive. The responses of these tissues are thought to be mediated via beta 2-adrenoceptors whereas cardiac and ileal responses are beta 1-adrenoceptor mediated. The latter receptor subtype would therefore appear to be under the influence of sympathetic innervation, but since no supersensitivity occurred at beta 2-adrenoceptors these were presumed to be non-innervated but stimulated by circulating adrenaline. These results obtained by use of chemical sympathectomy with 6-hydroxydopamine support the contention that the physiological basis of beta-adrenoceptor subclassification is that the beta 1-subtype are innervated whereas the beta 2-subtype are non-innervated.

Adrenergic beta-Agonists↗
PubMed1983

Cerebral infarction due to carotid occlusion and carbon monoxide exposure. II. Influence of preganglionic cervical sympathectomy.

Unilateral cerebral infarcts were produced in the rat by ligation of one common carotid artery and subsequent exposure to carbon monoxide. The incidence and extension of brain infarcts was increased in animals with additional ipsilateral cervical preganglionic sympathectomy. Sympathectomy did not affect markedly the respiration and systemic circulation. The effect of sympathectomy was attributed to a cutaneous vasodilation, leading to an extracranial steal phenomenon.

Animals↗
PubMed1987

Ethanol-induced cardiac hypertrophy: effects of peripheral sympathectomy.

The development of cardiac hypertrophy was examined in rats that had undergone sympathectomy with 6-hydroxydopamine. After 4 days, the rats were given severely intoxicating doses of ethanol or isocalorically paired quantities of maltose-dextrin by intubation at 8-h intervals up to 48 h. The ethanol and sugar intubations were applied in a nutritionally adequate, liquid diet mix. The extent of the peripheral sympathectomy was evident from the absence of detectable quantities of noradrenaline in hearts of animals injected with the neurotoxin and in the reduced levels of excreted noradrenaline. The adrenal medullary catecholamine contents of sympathectomized rats were unchanged in the absence of ethanol; there were reduced quantities of adrenaline in the medullae of rats given ethanol. The adrenal glands of rats given ethanol were larger than those from control animals. Urine samples from sympathectomized and control rats, given ethanol, displayed equivalent increases in excreted adrenaline and noradrenaline. Increases in relative cardiac weight were evident in hearts from sympathectomized animals after 4 days of sympathectomy, and this change reached significance in the hearts from 6-hydroxydopamine-treated rats after a further 2 days on the control diet. Hearts from animals exposed to ethanol showed a marked, rapid development of cardiomegaly; after 24 h there was an increased mass of some 17%, which was sustained over the remaining 24-h period. The proportion of cardiac protein did not differ in the large hearts from ethanol-treated animals and those from their controls, hence myocardial oedema could not account for the increase in weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗
PubMed1994

Effect of surgical sympathectomy on arterial blood flow in reflex sympathetic dystrophy: Doppler US assessment.

PURPOSE: To assess duplex Doppler ultrasound (US) in providing objective, reproducible measurements of blood flow in patients with reflex sympathetic dystrophy (RSD) who underwent surgical sympathectomy. MATERIALS AND METHODS: Findings in eight adult patients with RSD who were evaluated with arterial duplex Doppler US after surgical sympathetectomy were retrospectively reviewed. Pulsatility index (PI) and waveform characteristics were compared to clinical findings (temperature and sudomotor state) in sympathectomized limbs. RESULTS: Warm and dry limbs yielded a consistently low PI (usually less than 2) and biphasic waveform. Cold and clammy limbs, which indicated failed sympathectomy, produced a high PI (usually greater than 4) and triphasic waveform. The Doppler waveform promptly reverted with the return of sympathetic tone in patients who had clinical relapse. CONCLUSION: Duplex Doppler US may be useful for objective follow-up of RSD patients after sympathectomy.

Adult↗
PubMed1997

Effects of chemical sympathectomy and sensory nerve ablation on experimental colitis in the rat.

We assessed the effects of primary afferent nerve ablation (systemic treatment with capsaicin during adult or neonatal periods), primary afferent nerve activation (intracolonic capsaicin), and sympathectomy [6-hydroxydopamine (6-OHDA)] on the development of colitis induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS) in rats. We also examined whether lidocaine was effective after ablation of primary afferent nerves or sympathectomy. Colitis was assessed by macroscopic scoring, measurement of myeloperoxidase (MPO) activity, and histology. Systemic capsaicin treatment in adults increased the macroscopic damage score. Capsaicin treatment of neonates did not significantly increase damage score or MPO activity compared with vehicle-treated controls. However, all capsaicin-treated groups had a higher mortality. Intracolonic capsaicin treatment did not alter the severity of colitis. Chemical sympathectomy resulted in a decreased damage score and improved histology compared with controls. In 6-OHDA pretreated rats, lidocaine administration reduced the macroscopic and histological scores and MPO activity almost to control levels. However, lidocaine administration in capsaicin-treated rats attenuated the macroscopic damage but did not improve MPO activity or histology. These data suggest that capsaicin-sensitive nerves play a protective role in experimental colitis and sympathetic nerves contribute to the development of colitis. The beneficial effects of lidocaine appear to be due primarily to its action on enteric nerves.

Administration, Topical↗
PubMed1982

Circulatory effects of chemical sympathectomy in fetal, neonatal, and adult sheep.

Circulatory effects of chemical sympathectomy with 6-hydroxydopamine (6-HD), including changes in vascular sensitivity to neurotransmitters, were investigated in chronically instrumented unanesthetized fetal, neonatal, and adult sheep. In all animals acute response to 6-HD consisted of hypertension and tachycardia, which lasted 2-3 h. Chronic phase of sympathetic ablation then followed during which arterial pressure and heart rate of sympathectomized fetus and neonate returned to and remained at levels observed in intact animals, whereas adult sheep were slightly hypotensive throughout this period. In all animals supersensitivity of peripheral circulation to norepinephrine occurred, but only the fetus exhibited supersensitivity to acetylcholine and isoproterenol. Our conclusions are as follows: 1) acute phase of chemical sympathectomy in fetal, neonatal, and adult sheep simulates strong adrenergic stimulation; 2) absence of significant alteration in arterial pressure of fetus and neonate during the chronic phase of sympathectomy suggests a minor role for the adrenergic system in the maintenance of resting tone of peripheral circulation; and 3) on the basis of present and previous data, we postulate that the supersensitivity of fetal circulation to acetylcholine and isoproterenol may be secondary to changes occurring in pulmonary vascular bed.

Acetylcholine↗
PubMed1997

Effect of neonatal sympathectomy on development of angiotensin II-induced hypertension.

We tested, in the early stage of angiotensin II (ANG II)-induced hypertension, whether sympathectomy prevented the autopotentiation of vasoconstrictor responses by ANG II and, in the chronic, established phase of hypertension, whether the antihypertensive effect of sympathectomy, if any, was related to the prevention of structural vascular changes. Neonatally and sham-sympathectomized male Sprague-Dawley rats received 100 or 200 ng x kg(-1) x min(-1) ANG II intraperitoneally for 7-10 days or 200 ng x kg(-1) x min(-1) ANG II subcutaneously for 4 wk. Sham-treated sympathectomized and sham-sympathectomized rats were controls. Vasoconstrictor responses to ANG II, norepinephrine (NE), arginine vasopressin, and periarterial nerve stimulation were measured in the mesentery of rats, and thereafter, in the chronically treated rats, mesenteric resistance arteries were fixed in situ for morphometric measurements. In ANG II-treated sham-sympathectomized rats: 1) tail systolic blood pressure was unchanged after 7-10 days and increased by 23 mmHg at 4 wk (P < 0.001); 2) vasoconstrictor responses were selectively increased to ANG II (autopotentiation; P = 0.026) and nerve stimulation (P = 0.031) at 7-10 days and nonselectively increased to all stimuli at 4 wk (P < 0.05 to P < 0.01); and 3) after 4 wk, the wall-to-lumen ratio of resistance arteries was increased (P < 0.02). In ANG II-treated sympathectomized rats, there were no changes in systolic blood pressure or vasoconstrictor responses at either 7-10 days or 4 wk, but structural vascular changes developed to the same extent as in sham-sympathectomized ANG II-treated rats. Autopotentiation of vasoconstrictor responses appears to be due to an interaction between ANG II and the sympathetic nervous system, because it is prevented by sympathectomy. The dissociation of function and structure in the chronic stage of ANG II administration to sympathectomized rats suggests that structural vascular changes by themselves are insufficient to cause hypertension, but increased vascular reactivity or vasoconstrictor input is also needed.

Angiotensin II↗
PubMed1993

Cervical sympathectomy reduces the heterogeneity of oxygen saturation in small cerebrocortical veins.

This study evaluated the hypothesis that the peripheral sympathetic nervous system is one of the factors increasing the heterogeneity of venous O2 saturation in selective brain regions. Regional cerebral blood flow and O2 saturation were determined in the anterior cortex, posterior cortex, and medulla of either sham-operated or bilaterally sympathectomized Long-Evans rats. Cerebral venous O2 saturations, indicating the balance between local O2 supply and consumption, were found to be significantly more heterogeneous in the sham-operated group. In the anterior cortex, the coefficient of variation [100(SD/mean)] for the sham-operated animals was 22.4%. Sympathectomy significantly reduced this heterogeneity in the anterior cortex through a reduction in the number of low O2 saturation veins (coefficient of variation 11.7%). Blood flow and O2 consumption in the anterior cortex were not different between groups. The effects of sympathectomy in the posterior cortex were similar to those in the anterior cortex. However, sympathectomy did not alter any measured variables in the medulla. Thus, bilateral superior cervical ganglionectomy reduced the heterogeneity of cerebrocortical venous O2 saturation by reducing the number of low O2 saturation veins in the rostral part of the brain.

Animals↗
PubMed1993

Sympathectomy and beta-adrenergic blockade during lung maturation stimulated by TRH and cortisol in fetal sheep.

To test whether beta-adrenergic mechanisms and the sympathetic nervous system are involved in the synergistic action of thyrotropin-releasing hormone (TRH) and cortisol on lung maturation, fetal sheep (n = 32) were infused from 121 to 128 days of gestation with saline, TRH + cortisol, TRH + cortisol + beta-adrenergic blocker, or TRH + cortisol after chemical sympathectomy with 6-hydroxydopamine. TRH + cortisol increased lung distensibility and stability and alveolar concentrations of saturated phosphatidylcholine two- to threefold over control fetuses. beta-Adrenergic blockade prevented the increase in distensibility in response to TRH + cortisol. Sympathectomy did not impair the increase in distensibility and stability in response to TRH + cortisol but inhibited the increase in alveolar total phospholipids. Tissue concentrations of saturated phosphatidylcholine increased in TRH + cortisol-treated fetuses after either sympathectomy or beta-adrenergic blockade. We concluded that during lung maturation by TRH + cortisol 1) sympathetic mechanisms are requisite for surfactant release, 2) nonneurogenic beta-adrenergic mechanisms are requisite for the maturation of the mechanical properties of the lung and 3) stimulation of surfactant synthesis is independent of beta-adrenergic action and the sympathetic nervous system.

Adrenergic beta-Antagonists↗
PubMed2002

Effects of chronic sympathectomy on locally mediated cutaneous vasodilation in humans.

In human skin, the vasodilator response to local heating includes a sensory nerve-dependent peak followed by a nadir and then a slower, nitric oxide-mediated, endothelium-dependent vasodilation. To investigate whether chronic sympathectomy diminishes this endothelium-dependent vasodilation, we studied individuals who had previously undergone surgical T(2) sympathectomy (n = 9) and a group of healthy controls (n = 8). We assessed the cutaneous vascular response (laser-Doppler) to 30 min of local warming to 42.5 degrees C on the ventral forearm (no sympathetic innervation) and the lower legs (sympathetic nerves intact). Lower body negative pressure (LBNP) was measured to confirm sympathetic denervation. During local warming in sympathectomized individuals, vascular conductance reached an initial peak at both sites [achieving 1.73 +/- 0.22 laser-Doppler units (LDU)/mmHg in the forearm and 1.92 +/- 0.21 LDU/mmHg in the leg]. It then decreased to a nadir in the innervated leg [to 1.77 +/- 0.23 LDU/mmHg (P < 0.05)] but not in the sympathectomized arm (1.69 +/- 0.21 LDU/mmHg; P > 0.10). The maximal vasodilation seen during the slower phase was not different between limbs or between groups. Furthermore, LBNP caused a 44% reduction in forearm vascular conductance (FVC) in control subjects, but FVC did not decrease significantly in sympathectomized individuals, confirming sympathetic denervation. These data indicate that endothelial function in human skin is largely preserved after sympathectomy. The altered pattern of the response suggests that the nitric oxide-dependent portion may be accelerated in sympathectomized limbs.

Adult↗
PubMed2002

Effects of chronic sympathectomy on vascular function in the human forearm.

To determine whether endothelial function is altered by chronic surgical sympathectomy, we infused ACh, isoproterenol, nitroprusside (NTP), and the nitric oxide synthase inhibitor NG-mono-methyl-L-arginine (L-NMMA) into the brachial arteries of nine patients 5-64 mo after thoracic sympathectomy for hyperhidrosis. Age- and gender-matched controls were also studied. Forearm blood flow (FBF) was measured by venous occlusion plethysmography. Lower body negative pressure was used to assess reflex vasoconstrictor responses. Tyramine, which acts locally and causes norepinephrine release from sympathetic nerves, was also administered via the brachial artery. FBF at rest was 2.5 +/- 0.4 ml x dl-1 x min-1 in the patients and 2.5 +/- 0.3 ml x dl-1 x min-1 in the controls (P = 0.95). The normal vasoconstrictor responses to lower body negative pressure were abolished in the patients. By contrast, tyramine produced dose-dependent vasoconstriction in the patients that was identical to that of controls. The dose-response curves to ACh were similar in patients and controls, with maximum values of 19.3 +/- 4.4 vs. 25.5 +/- 2.8 ml x dl-1 x min-1, respectively. L-NMMA reduced baseline FBF similarly and reduced the maximal FBF response to ACh in both groups (patients 8.9 +/- 3.5 vs. controls 9.7 +/- 2.5 ml x dl-1 x min-1). The vasodilation to isoproterenol was similar and blunted to the same extent in both groups by L-NMMA. The responses to NTP in patients and controls were similar and not affected by L-NMMA. We conclude that, in humans, chronic surgical sympathectomy does not cause major disruptions in vascular function in the forearm. The normal vasoconstrictor responses to tyramine indicate that there were viable sympathetic nerves in the forearm that were not engaged by LBNP.

Adult↗
PubMed2000

Effect of thoracic sympathectomy on arm and leg exercise capacity and on lung function.

BACKGROUND: Thoracic T(2-4) sympathectomy (TS) relieves palmar hyperhidrosis. These same roots innervate the heart and the lung. Thoracoscopic TS minimizes damage to the chest wall so that the effect of sympathectomy itself on these organs can be studied. We attempted to determine whether attenuated sympathetic output affects arm or leg exercise tolerance and lung function in young adults who underwent this operation. METHODS: Seven subjects, aged 17-30 years, had lung function tests (water spirometer, Godart, Holland), and leg and arm maximal exercise (CPX, MedGraphics, USA), before and 3-6 months after TS. RESULTS: After TS, resting and exercise heart rate and blood pressure were reduced. Baseline leg and arm peak O(2) uptake, 2.08 (0.6) and 1.44 (0.5) liters/min, respectively, were not different from the post-TS values, 2.06 (0.7) and 1.54 (0.5) liters/min (nonsignificant). Post-TS lung functions were not significantly reduced. CONCLUSION: Thoracoscopic T(2-4) sympathectomy does not lead to a clinically important fall in lung function and does not compromise arm or leg exercise capacity. Therefore, TS can be done safely in young subjects with palmar hyperhidrosis.

Adolescent↗
PubMed1997

Video-endoscopic and mini-endoscopic sympathectomy for hyperhidrosis.

Video-endoscopic sympathectomy (VES) is currently the method of choice for the minimally invasive treatment of hyperhidrosis involving the palms, armpit and facial areas. Over a 7-year period from 1991 to 1997 our technique of performing VES has evolved during the performance of 800 endoscopic sympathectomies from the use of 3 ports to a single 10-mm port to finally a 3-mm port using a mini-endoscope. In comparison to standard VES, mini-endoscopic sympathectomy is simpler, less invasive, causes less postoperative discomfort and consistently allows patients to return home the same day.

Adult↗
PubMedDate not supplied

Long-term guanethidine sympathectomy suppresses flow-induced release of ATP and endothelin from endothelial cells isolated from adult rat aorta.

Chronic rather than acute changes in the autonomic innervation of the vasculature are a feature of ageing and several cardiovascular disorders. To investigate the long-term influence of perivascular innervation on the vascular endothelium, the release of vasoactive substances which have been localized in endothelial cells, namely ATP, endothelin, substance P and vasopressin, was monitored from cells isolated from adult rat thoracic aorta following neonatal guanethidine sympathectomy. The endothelial cells were initially perfused at 0.5 ml/min and exposed to two periods of increased flow at 3.0 ml/min. Cells isolated from control rats released significantly more ATP on both occasions of switching from the lower to higher flow rate and significantly more endothelin on the second exposure to the higher flow rate. In contrast, endothelial cells isolated from sympathectomised rats showed no increased release of either ATP or endothelin with increase flow, although the release of endothelin at the initial flow rate of 0.5 ml/min was higher than in the controls. Substance P and vasopressin levels in the perfusate were the same in controls and after sympathectomy. In summary, long-term sympathectomy suppresses increased flow-induced release of selected vasoactive substances from the endothelium, thus shear-stress-induced changes in local blood flow may be impaired when there are chronic disturbances in the autonomic innervation.

Adenosine Triphosphate↗
PubMed1995

Subsequent biological effects of chemical sympathectomy in rats undergoing unilateral testicular torsion.

The effects of chemical sympathectomy on contralateral testicular histology, fertility and fecundity following unilateral testicular torsion were evaluated in rats. Four groups, placebo plus sham operation, 6-OH-dopamine plus sham operation, placebo plus torsion, and 6-OH-dopamine plus torsion, were established. When the placebo plus sham operation and placebo plus torsion groups were compared, it was found that contralateral testicular damage following unilateral testicular torsion occurred with significantly decreased values for mean seminiferous tubular diameter (MSTD), mean testicular biopsy score (MTBS) and fertility. The relatively normal values for MSTD, MTBS and fertility in the 6-OH-dopamine plus sham operation and 6-OH-dopamine plus torsion groups indicate the preventive role of chemical sympathectomy on contralateral testicular damage. Since chemical sympathectomy prevents contralateral histologic deterioration and preserves fertility in unilateral testicular torsion, the decreased blood flow in the reflex-activating sympathetic system may play a role in contralateral testicular damage.

Animals↗