1 Integrated Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, Københavns Universitet2 Integrated Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, Københavns Universitet
In skeletal muscle, growth of capillaries is an important adaptation to exercise training that secures adequate diffusion capacity for oxygen and nutrients even at high intensity exercise when increases in muscle blood flow are profound. Mechanical forces present during muscle activity, such as shear stress and passive stretch, lead to cellular signalling, enhanced expression of angiogenic factors and initiation of capillary growth. The most central angiogenic factor in skeletal muscle capillary growth is vascular endothelial growth factor (VEGF). During muscle contraction, VEGF increases in the muscle interstitium, acts on VEGF receptors on the capillary endothelium and thereby stimulates angiogenic processes. A primary source of muscle interstitial VEGF during exercise is the skeletal muscle fibers which contain large stores of VEGF within vesicles. We propose that, during muscle activity, these VEGF containing vesicles are redistributed towards the sarcolemma where the contents are secreted into the extracellular fluid. VEGF mRNA expression is increased primarily after exercise, which allows for a more rapid replenishment of VEGF stores lost through secretion during exercise. Future studies should focus on elucidating mechanisms and regulation of VEGF secretion. This article is protected by copyright. All rights reserved.
Journal review article
Microcirculation, 2014, Vol 21, Issue 4, p. 301-314