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1 Department of Exercise and Sport Science, East Carolina University, Greenville, NC, USA; Department of Physiology, East Carolina University, Greenville, NC, USA; Human Performance Laboratory, East Carolina University, Greenville, NC, USA
2 Department of Exercise and Sport Science, East Carolina University, Greenville, NC, USA; Human Performance Laboratory, East Carolina University, Greenville, NC, USA
3 Department of Surgery, East Carolina University, Greenville, NC, USA
* To whom correspondence should be addressed. E-mail: gavint{at}mail.ecu.edu.
Obesity is associated with lower skeletal muscle capillarization and lower insulin sensitivity. Vascular endothelial growth factor (VEGF) is important for the maintenance of the skeletal muscle capillaries. To investigate if VEGF and VEGF receptor (KDR and Flt-1) expression are lower with obesity, vastus lateralis muscle biopsies were obtained from eight obese and eight lean young sedentary men prior to and 2 hr after a 1 hr sub-maximal aerobic exercise bout for the measurement of VEGF, KDR, Flt-1, and skeletal muscle fiber and capillary characteristics. There were no differences in VEGF or VEGF receptor mRNA at rest between lean and obese muscle. Exercise increased VEGF (10-fold), KDR (3-fold), and Flt-1 (5-fold) mRNA independent of group. There were no differences in VEGF, KDR, or Flt-1 protein between groups. Compared to lean skeletal muscle, the number of capillary contacts per fiber was the same, but lower capillary density (CD), greater muscle cross sectional area, and lower capillary-to-fiber area ratio (CFA) were observed in both type I and II fibers in obese. Multiple linear regression revealed that 49% of the variance in insulin sensitivity (HOMA) could be explained by percentage of body fat (35%) and VO2MAX per kg fat free mass (14%). Linear regression revealed significant relationships between VO2MAX and both CD and capillary-to-fiber perimeter exchange (CFPE). While differences may exist in CD and CFA between lean and obese skeletal muscle, the current results provide evidence that VEGF and VEGF receptor expression are not different between lean and obese muscle.
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