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- Title
Local sympathetic function in human skeletal muscle and adipose tissue assessed by microdialysis.
- Authors
Bruce, Simon; Tack, Cees; Patel, Jigisha; Pacak, Karel; Goldstein, David S.
- Abstract
Background In response to stressors and pathophysiologic conditions, sympathetic neuronal outflows can change heterogeneously among body organs and tissues. This study examined the validity of micro dialysis and measurements of microdialysate concentrations of catechols, to assess local sympathetic function in skeletal muscle and adipose tissue in humans. Methods Based on preliminary experiments, a microdialys ate perfusion rate of 3 μl/mm and collection duration of 30 minutes were chosen. To assess responses to a stimulus that increases sympathetic outflow to skeletal muscle, micro dialysate norepinephrine and dihydroxyphenylglycol concentrations in quadriceps muscle, abdominal subcutaneous adipose tissue, and plasma were measured during orthostasis in 8 healthy normal volunteers. To assess responses to decreased post- ganglionic sympathetic nerve traffic, norepinephrine and dihydroxyphenylglycol concentrations were measured during i. v. infusion of trimethaphan in 5 volunteers. Results All subjects had detectable norepinephrine and dihydroxyphenylglycol in micro- dialysate from both skeletal muscle and adipose tissue. Orthostasis sig- nificantly increased micro dialysate norepinephrine in skeletal muscle (0.38 ± (SEM) 0.07 nmol/L supine to 1.48 ± 0.24 nmol/L standing, p <0.01) and in adipose tissue (0.31 ± 0.02 nmol/L supine to 0.68 ± 0.11 nmol/L standing, p <0.01). Orthostasis also increased microdialysate dihydroxyphenylglycol in both tissues (1.76 ± 0.30 nmol/L to 3.08 ± 0.43 nmol/L,p <0.01; 1.37 ± 0.15 nmol/L supine to 1.99 ± 0.34nmol/L standing,p <0.01). Trimethaphan decreased norepinephrine concentrations in skeletal muscle micro dialysate by 50 %, adipose tissue by 70 %, and antecubital venous plasma 50 %, with non-significant decreases in dihydrox- yphenylglycol concentrations at each site. Conclusions Microdialysate concentrations of nor epinephrine and dihydroxyphenylglycol can be detected reliably and respond appropriately during manipulations that increase or decrease the sympathetically mediated release and turnover of norepinephrine. This approach may provide a means to assess sympathetic neuronal function in skeletal muscle and adipose tissue in humans with known or suspected dysautonomias.
- Subjects
PATHOLOGICAL physiology; CONNECTIVE tissues; ADIPOSE tissues; POLYPHENOLS; NORADRENALINE; SYMPATHOMIMETIC agents
- Publication
Clinical Autonomic Research, 2003, Vol 13, Issue 1, p13
- ISSN
0959-9851
- Publication type
Article