Increased expression of vascular endothelial growth factor in human skeletal muscle in response to short-term one-legged exercise training

The effects of short-term exercise training on vascular endothelial growth factor (VEGF) and one of its regulatory transcription factors, the hypoxia inducible factor 1 (HIF-1) subunit, were studied in eight healthy males. Muscle and blood samples were obtained before the 1st, and 24 h after the 7th training session. VEGF and HIF-1 mRNA were analysed using RT-PCR, VEGF mRNA localization with in situ hybridization and VEGF protein with ELISA. Concurrent increases in VEGF mRNA and protein levels were observed in skeletal muscle, and the mRNA was expressed within the skeletal muscle fibres and in cells in the interstitium. These data support the idea of a pretranslational regulation of exercise-induced changes in VEGF mRNA, and indicate that increased VEGF protein expression is an early event in skeletal muscle adaptation to training. Furthermore, different cell types may act as sources for the production of angiogenic factors in response to exercise. The levels of HIF-1 mRNA subunits did not change, suggesting no change in HIF-1 mRNA transcript levels in the regulation of training-induced VEGF expression. In contrast to increased tissue VEGF expression, the arterial and femoral venous plasma levels of VEGF were decreased by training, which may indicate an exercise-induced enhancement of the peripheral uptake of VEGF.