Reduced oxygenation in human obese adipose tissue is associated with impaired insulin suppression of lipolysis.
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.
Pasarica
Magdalena
M
Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, Louisiana 70808, USA.
Rood
Jennifer
J
Ravussin
Eric
E
Schwarz
Jean-Marc
JM
Smith
Steven R
SR
Redman
Leanne M
LM
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
D001786:Blood Glucose; D007328:Insulin
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