Influence of adiposity on tonic sympathetic support of resting metabolism in healthy adults.
BACKGROUND
beta-Adrenergic receptor sympathetic nervous system (beta-AR SNS) support of resting metabolic rate (RMR) is attenuated with older age, female sex, and a sedentary lifestyle. Total and abdominal adiposity and/or body fat pattern modulate some SNS-mediated physiological functions.


OBJECTIVE
To determine if total and abdominal adiposity and/or body fat distribution are independently related to SNS support of RMR.


METHODS
Cross-sectional comparison of beta-AR SNS support of RMR.


METHODS
A total of 54 healthy male and female subjects aged 18-75 y.


METHODS
RMR (ventilated hood, indirect calorimetry) before (baseline) and during complete beta-AR blockade; body composition by dual energy X-ray absorptiometry.


RESULTS
Forward stepwise multiple regression analysis using sex, exercise status, age group, %body fat, total adiposity, abdominal adiposity, and the ratio of abdominal adiposity to hip adiposity as variables revealed sex to be the strongest predictor, explaining 21% of the variability in beta-AR SNS support of RMR (P=0.0006). Age group explained an additional 4% and exercise status a further 4% (both P=0.10). %Body fat, total adiposity, abdominal adiposity, and the ratio of abdominal adiposity to hip adiposity did not enter the equation.


CONCLUSIONS
Total and abdominal adiposity and body fat pattern are not independent physiological determinants of beta-AR SNS support of RMR among healthy men and women. Moreover, further support is provided for our previous finding of attenuated beta-AR SNS support of RMR with age, female sex, and sedentary lifestyle.
Department of Integrative Physiology, University of Colorado, Boulder, CO 80309, USA. Christopher.Bell@Colorado.edu
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Bell
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Petitt
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Jones
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Seals
D000005:Abdomen / Q000033:anatomy & histology; D000273:Adipose Tissue / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D001823:Body Composition / Q000502:physiology; D003430:Cross-Sectional Studies; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D012189:Retrospective Studies; D013564:Sympathetic Nervous System / Q000502:physiology*
D011943:Receptors, Adrenergic, beta