Conclusion
These results indicate that low capillary density and ATpO2 in AT are potentially upstream causes of AT dysfunction.
Objective
Our objective was to test whether hypoxia is associated with reduced antilipolytic effect of insulin. Participants, design, and setting: Twenty-one lean and obese individuals participated in this cross-sectional study at a university-based clinical research center. Intervention: 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). Main outcome measure: 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).
Trial registration
ClinicalTrials.gov NCT00704197.