Angiogenic growth factor mrna responses in muscle to a single bout
of exercise.
Breen, E. C., Johnson, E. C., Wagner, H., Tseng, H. M., Sung, L. A.
and Wagner, P. D.
Department of Medicine, University of California San Diego, La
Jolla, CA 92093-0623
APStracts 3:0112A, 1996.
A major adaptation to exercise is new capillary formation in skeletal
muscle. Based on angiogenesis in tumors, and during development,
several angiogenic growth factors may be involved including vascular
endothelial growth factor (VEGF), basic fibroblast growth factor
(bFGF) and transforming growth factor [beta]1 (TGF-[beta]1). In 9
week old female Wistar rats, mRNA expression for these three growth
factors in gastrocnemius muscle was examined by quantitative Northern
analysis following a single one hour run at either 15 or 20 m/min at
10 degrees incline breathing air. A third group ran at 15 m/min
breathing 12% O2 and resting control groups were included at Fio2 =
0.21 and 0.12. Exercise significantly increased mRNA levels two to
four fold, evident over the first four hours post-exercise; by 8 and
24 hours mRNA levels were back to baseline. For all three factors,
mRNA levels were significantly higher after 20 than 15 m/min
exercise. Hypoxia at rest doubled VEGF and TGF-[beta]1 message with
no effect on bFGF. Hypoxic exercise further raised VEGF mRNA levels
but had no effect on the other factors. We suggest that VEGF, bFGF
and TGF-[beta]1 may be involved in the angiogenic response to
exercise and that reduced intracellular Po2 (as occurs during
normoxic exercise) may be part of the stimulus to such growth factor
production.
Received 17 November 1995; accepted in final form 7 February
1996.
APS Manuscript Number A1204-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 March 96