Background
Physical exercise benefits the heart, but the mechanism is not understood. The mechanism of muscle plasticity after physical training is also unclear. The proangiogenic and mitogenic activity of PDGF and VEGF could be involved in both processes. This study investigated the influence of a single bout of acute exercise on the PDGF-AA and VEGF-A expression in skeletal and heart muscle in untrained rats and in those subjected to prolonged endurance training (trained).
Material and Method
Fifty-nine rats were randomly assigned to the untrained (UT) or trained (T, subjected to 6-week endurance training) groups. The groups were subjected to an acute bout of exercise with the same work load a day after final training. Rats of both groups were sacrificed and skeletal and heart muscle samples were collected before, immediately after (0 h), or 3 hours (3 h) after acute exercise.
Results
Prolonged training caused an increase in PDGF-AA mRNA (p=0.038) and protein (p=0.016) in rat skeletal muscle (T vs. UT). A similar pattern was observed in VEGF-A, but the changes were not significant. Acute exercise caused a significant decrease in PDGF-AA mRNA after 0 and 3 h (p=0.03 and p=0.04, respectively). In the heart there were no significant changes in either mRNA after acute exercise or after endurance training.
Conclusions
Six-week endurance training in rats increases PDGF-AA mRNA and protein in skeletal, but not in heart muscle.

Keywords: Reverse Transcriptase Polymerase Chain Reaction, RNA, Messenger - genetics, Platelet-Derived Growth Factor - metabolism, Myocardium - metabolism, Physical Conditioning, Animal, Bone and Bones - metabolism