title: Whole body fat oxidation is related to in situ adipose tissue lipolytic response to isoproterenol in males.
abstract: A high 24-h respiratory quotient (RQ), i.e., low fat oxidation, predicts weight gain. To determine whether impaired fat mobilization (lipolysis) may contribute to weight gain, we studied the relation between lipolytic response to nonselective beta-adrenergic stimulation and RQ measured in a respiratory chamber in 21 males (11 Caucasians, 10 Pima Indians; age 32 +/- 5 yr, weight 93 +/- 24 kg, body fat 30 +/- 8%; means +/- SD) and 23 females (10 Caucasians, 13 Pima Indians; age 32 +/- 9 yr, weight 95 +/- 26 kg, body fat 44 +/- 8%). Lipolytic response was assessed as the relative increase in dialysate glycerol concentration (% above baseline) when isoproterenol (1 micromol/l) was added to the perfusate of a microdialysis probe inserted in the abdominal subcutaneous adipose tissue. In males, but not in females, basal RQ measured during sleep from 0500 to 0630 and adjusted for waist circumference was negatively correlated to lipolytic response (r = -0.66, P = 0.001). The results suggest that in males, impaired beta-adrenergic-mediated lipolysis may contribute to low rates of fat oxidation, a condition known to predispose to weight gain.
authors.affiliation: Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona 85016, USA.
authors.forename: S
authors.initials: S
authors.lastname: Snitker
authors.forename: J
authors.initials: J
authors.lastname: Hellmér
authors.forename: M
authors.initials: M
authors.lastname: Boschmann
authors.forename: M B
authors.initials: MB
authors.lastname: Monroe
authors.forename: E
authors.initials: E
authors.lastname: Ravussin
mesh_terms: D000005:Abdomen; D000273:Adipose Tissue / Q000187:drug effects / Q000502:physiology*; D000328:Adult; D001823:Body Composition; D001824:Body Constitution; D002153:Calorimetry, Indirect; D005260:Female; D005990:Glycerol / Q000378:metabolism; D006801:Humans; D007198:Indians, North American; D007545:Isoproterenol / Q000494:pharmacology*; D050356:Lipid Metabolism; D008066:Lipolysis / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D012044:Regression Analysis; D012727:Sex Characteristics; D014481:United States; D044465:White People
chemical_list: D007545:Isoproterenol; D005990:Glycerol