Angiogenic growth factor responses to long-term treadmill exercise in mice.

We sought to determine whether VEGF and other angiogenic growth factors and their receptors might be subject to negative feedback regulation during two weeks of treadmill-exercise conditioning in inbred strains of mice. C57BL/6 mice exhibited greater VEGF mRNA and protein responses in gastrocnemius muscle to a single bout of treadmill exercise compared to BALB/c mice. The patterns of VEGF, VEGFR1, VEGFR2, Ang2 and Tie2 mRNA expression in gastrocnemius muscles of C57BL/6 mice during long-term exercise support the hypothesis that they may be subject to negative feedback regulation. The combination of expression patterns for growth factors and their receptors suggests that multiple layers of control mechanisms may exist to prevent angiogenesis following a single bout of exercise and to promote angiogenesis following long-term exercise.