Effects of Sympathectomy on Muscle

We have previously reported functional and histological studies in five beagle dogs with unilateral lumbar sympathectomy. Three months later, fatiguability in the gracilis muscles was increased on the denervated sides, and this was associated with an increase in the relative distribution of FT fibres. Biochemical studies now show that these changes were associated with an increase in cytosolic protein without change in DNA content; this is consistent with
an increase in cell size. There was a reduction in the proportion of slow myosin light chain isoforms from 50 ± 7 to 34 ± 6%. Noradrenaline levels were increased on the denervated sides but this may reflect greater vascularity. Calcium content did not correlate with fibre type but there was a positive relation with both noradrenaline content (r= 0·73;
P<0·05) and DNA content (r= 0·84; P<0·05). It is concluded that sympathectomy induces several biochemical changes in skeletal muscle which constitute a change and increase in fast myosin light chain synthesis and a corresponding fibre type transformation.

Clinical Physiology (Oxford, England) 1988 Apr; vol 8 (issue 2): pp 181-91

2.
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.

International Journal of Experimental Pathology
Volume 82, Issue 2, pages 123–128, April 2001

Sympathectomy limits blood flow to a vital organ like the brain

1. Acta Physiol Scand. 2000 Sep;170(1):33-8.

Middle cerebral artery blood velocity during exercise with beta-1 adrenergic and unilateral stellate ganglion blockade in humans.

Ide K, Boushel R, Sørensen HM, Fernandes A, Cai Y, Pott F, Secher NH.

Department of Anaesthesia, The Copenhagen Muscle Research Centre, University of Copenhagen, Rigshospitalet, Denmark.

A reduced ability to increase cardiac output (CO) during exercise limits blood flow by vasoconstriction even in active skeletal muscle. Such a flow limitation may also take place in the brain as an increase in the transcranial Doppler determined middle cerebral artery blood velocity (MCA V(mean)) is attenuated during cycling with beta-1 adrenergic blockade and in patients with heart insufficiency. We studied whether sympathetic blockade at the level of the neck (0.1% lidocaine; 8 mL; n=8) affects the attenuated exercise - MCA V(mean following cardio-selective beta-1 adrenergic blockade (0.15 mg kg(-1) metoprolol
i.v.) during cycling. Cardiac output determined by indocyanine green dye dilution, heart rate (HR), mean arterial pressure (MAP) and MCA V(mean) were obtained during moderate intensity cycling before and after pharmacological intervention. During control cycling the right and left MCA V(mean) increased to the same extent (11.4 1.9 vs. 11.1 1.9 cm s(-1)). With the
pharmacological intervention the exercise CO (10 1 vs. 12 1 L min(-1); n=5), HR (115 4 vs. 134 4 beats min(-1)) and delta MCA V(mean) (8.7 2.2 vs. 11.4 1.9 cm s(-1) were reduced, and MAP was increased (100 5 vs. 86 2 mmHg; P < 0.05).

However, sympathetic blockade at the level of the neck eliminated the beta-1 blockade induced attenuation in delta MCA V(mean) (10.2 2.5 cm s(-1)). These results indicate that a reduced ability to increase CO during exercise limits blood flow to a vital organ like the brain and that this flow limitation is likely to be by way of the sympathetic nervous system.

PMID: 10971220 [PubMed - indexed for MEDLINE]