In the developing countries, obesity prevalence is on a dramatic rise. Obesity is related to co-morbidities and as a result, obesity significantly shortens life expectancy and lowers quality of life. To prevent this, participation in exercise or training programs is absolutely necessary, in order to generate adipose tissue mass loss. The amount of adipose tissue mass loss is, amongst others, dependent on lipolysis which is under endocrine regulation by, mainly, catecholamines, insulin and atrial natriuretic peptide. However, large variations in adipose tissue mass loss and gain are likely in obese subjects, possibly due to a decreased lipolytic effect of these hormones (as was shown for catecholamines in the subcutaneous adipose tissue of obese subjects). However, the relative contribution of atrial natriuretic peptide in the lipolytic process remains elusive, particularly in subjects with obesity, which show an increased plasma expression of atrial natriuretic peptide. The aim of the present study is to observe the contribution of atrial natriuretic peptide in the subcutaneous adipose tissue of obese subjects. This will be tested by measurements of extracellular glycerol levels (by microdialysis) in the subcutaneous adipose tissue in situ at rest and during endurance exercise under local beta- and alpha-blockade. Eventually, the knowledge gained from this research will contribute to the optimization of exercise programs for people with obesity.
Study Type
OBSERVATIONAL
Enrollment
30
adipose tissue lipolysis under local beta/alpha blockade in abdominal subcutaneous adipose tissue, using microdialysis
Hasselt University
Diepenbeek, Belgium
Subcutaneous adipose tissue microdialysis
abdominal subcutaneous adipose tissue microdialysis during rest and exercise; basal + under local alpha- and beta-blockade.
Time frame: week 1
Atrial natriuretic peptide (ANP) Response
measurement systemic ANP response (venous blood sampling)
Time frame: week 1
Central insulin sensitivity
Fasting serum insulin, homeostasis model assessment insulin resistance and measures of central insulin sensitivity derived from an oral glucose tolerance test (75g)
Time frame: screening
Echocardiography
heart function by means of standard echocardiography
Time frame: Day 1
Maximal oxygen uptake (ml/O2/kg/min)
measured using indirect calorimetry and an incremental bicycle protocol
Time frame: Day 1
Anthropometry
body composition, measured using dual x-ray absorptiometry, height, weight, waist and hip circumference
Time frame: screening
Abdominal subcutaneous adipose tissue biopsy
biochemical, proteomics and morphological analyses
Time frame: week 1
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