Online citations, reference lists, and bibliographies.
Referencing for people who value simplicity, privacy, and speed.
Get Citationsy
← Back to Search

Chronic Hypoxia Attenuates Resting And Exercise-induced VEGF, Flt-1, And Flk-1 MRNA Levels In Skeletal Muscle

I. Mark Olfert, Ellen C. Breen, Odile Mathieu-Costello, Peter D. Wagner

Save to my Library
Download PDF
Analyze on Scholarcy Visualize in Litmaps
Share
Reduce the time it takes to create your bibliography by a factor of 10 by using the world’s favourite reference manager
Time to take this seriously.
Get Citationsy
Vascular endothelial growth factor (VEGF) is a hypoxia-inducible angiogenic mitogen. However, chronic hypoxia is generally not found to increase mammalian skeletal muscle capillarity. We sought to determine the effect of chronic hypoxia (8 wk, inspired O2 fraction = 0.12) on skeletal muscle gene expression of VEGF, its receptors (flt-1 and flk-1), basic fibroblast growth factor, and transforming growth factor-β1. Wistar rats were exposed to chronic hypoxia ( n = 12) or room air ( n = 12). After the exposure period, six animals from each group were subjected to a single 1-h treadmill exercise bout (18 m/min on a 10° incline) in room air while the remaining six animals served as rest controls. Morphological analysis revealed that chronic hypoxia did not increase skeletal muscle capillarity. Northern blot analyses showed that chronic hypoxia decreased resting VEGF, flt-1, and flk-1 mRNA by 23, 68, and 42%, respectively ( P < 0.05). The VEGF mRNA response to exercise was also decreased (4.1- and 2.7-fold increase in room air and chronic hypoxia, respectively, P < 0.05). In contrast, neither transforming growth factor-β1 nor basic fibroblast growth factor mRNA was significantly altered by chronic hypoxia. In conclusion, prolonged exposure to hypoxia attenuated gene expression of VEGF and its receptors flt-1 and flk-1 in rat gastrocnemius muscle. These findings may provide an explanation for the lack of mammalian skeletal muscle angiogenesis that is observed after chronic hypoxia.