Molecular control of capillary growth in skeletal muscle.

Angiogenesis, the growth of new capillaries, enhances the oxygen delivery capacity of an existing vascular network. This adaptation is a well-documented occurrence in exercising skeletal muscle. The purpose of this review is to summarize our current understanding of the various stimuli that are involved in the initiation of capillary growth in skeletal muscle. The roles of humoral and mechanical signals in the cellular regulation of several key angiogenic players, vascular endothelial cell growth factor and matrix metalloproteinases, will be discussed. Evidence will be presented supporting the existence of angiogenesis processes that are distinct from the "classically" defined process. Determining how specific angiogenic stimuli can initiate unique patterns of capillary growth will provide insight into the complex task of developing effective pro-angiogenic therapies.