title: Reduced oxygenation in human obese adipose tissue is associated with impaired insulin suppression of lipolysis.
abstract: BACKGROUND
  Adipose tissue in obese individuals is characterized by reduced capillary density and reduced oxygenation.
  
  
  OBJECTIVE
  Our objective was to test whether hypoxia is associated with reduced antilipolytic effect of insulin.
  
  
  METHODS
  Twenty-one lean and obese individuals participated in this cross-sectional study at a university-based clinical research center.
  
  
  METHODS
  In all subjects, in situ adipose tissue (AT) oxygenation [AT oxygen partial pressure (ATpO2)] was measured with a Clark electrode, insulin sensitivity as well as basal and insulin-suppressed lipolysis (continuous infusion of (2H5)glycerol) were measured during a euglycemic-hyperinsulinemic clamp, and abdominal sc AT biopsies were collected to assess fat cell size (Coulter counting of osmium-fixed cells), capillary density (by staining of histological sections), and gene expression (by quantitative RT-PCR).
  
  
  METHODS
  In situ ATpO2 was evaluated.
  
  
  RESULTS
  The ability of insulin to suppress lipolysis (percent) was positively correlated with insulin sensitivity (r=0.43; P<0.05), ATpO2 (r=0.44; P<0.05), vascular endothelial growth factor mRNA (r=0.73; P<0.01), and capillary density (r=0.75; P<0.01).
  
  
  CONCLUSIONS
  These results indicate that low capillary density and ATpO2 in AT are potentially upstream causes of AT dysfunction.
authors.affiliation: Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, Louisiana 70808, USA.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Pasarica
authors.forename: Jennifer
authors.initials: J
authors.lastname: Rood
authors.forename: Eric
authors.initials: E
authors.lastname: Ravussin
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Schwarz
authors.forename: Steven R
authors.initials: SR
authors.lastname: Smith
authors.forename: Leanne M
authors.initials: LM
authors.lastname: Redman
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000098:blood supply* / Q000378:metabolism*; D000704:Analysis of Variance; D001786:Blood Glucose / Q000378:metabolism; D001823:Body Composition; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism; D005260:Female; D015309:Glucose Clamp Technique; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D008066:Lipolysis / Q000502:physiology*; D008297:Male; D009765:Obesity / Q000378:metabolism*; D010101:Oxygen Consumption; D010313:Partial Pressure
chemical_list: D001786:Blood Glucose; D007328:Insulin
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