|Kraunsoee R, Boushel RC, Hansen CN, Schjerling P, Qvortrup K, Stoecke M, Mikines KJ, Dela F (2010) Mitochondrial respiration in subcutaneous and visceral adipose tissue from patients with morbid obesity. Mitochondr Physiol Network 15.6:50-1.|
Link: Abstracts Session 2
Adipose tissue exerts important endocrine and metabolic functions in health and disease. Yet the bioenergetics of this tissue is not characterized in humans and possible regional differences are not elucidated. Using high-resolution respirometry, mitochondrial respiration was quantified in human abdominal subcutaneous and intra-abdominal, visceral (omentum majus) adipose tissue from biopsies obtained in twenty obese patients undergoing bariatric surgery. mtDNA and gDNA were determined by PCR technique for estimation of mitochondrial density. Adipose tissue samples were permeabilized and respirometric measurements were performed in duplicate at 37 °C. Substrates [glutamate(G) + malate(M) + octanoyl carnitine(Oct) + succinate(S)] were added sequentially to provide electrons to Complexes CI + CII. ADP (D) for State 3 respiration was added after GM. Non-coupled respiration was measured after addition of FCCP. Visceral fat contained more mitochondria per mg tissue than subcutaneous fat, but the cells were smaller. Robust, stable oxygen fluxes were found in both tissues, and coupled State 3 (GMOctSD) and non-coupled respiration were significantly (P<0.05) higher in visceral (0.95±0.05 and 1.15±0.06 pmol O2∙s-1∙mg-1, respectively) compared with subcutaneous (0.76±0.04 and 0.98±0.05 pmol O2∙s-1∙mg-1, respectively) adipose tissue. Expressed per mtDNA, visceral adipose tissue had significantly (P<0.05) lower mitochondrial respiration. Substrate control ratios were higher and uncoupling control ratio lower (P<0.05) in visceral compared with subcutaneous adipose tissue.
Visceral fat is bioenergetically more active and more sensitive to mitochondrial substrate supply than subcutaneous fat. OXPHOS has a higher relative activity in visceral compared with subcutaneous adipose tissue.
Preparation: Permeabilized tissue
Regulation: Substrate, Fatty acid Coupling state: OXPHOS
Adipose tissue, mtDNA