FIG. 8.

Modulation of skeletal muscle by nitric oxide. nNOSμ associated with the sarcolemma may induce vasodilation, thereby increasing oxygen and nutrient supply by vasodilation. NO enhances AMPK activity and AMPK stimulates NO formation, leading to a feed-forward loop. Activated AMPK, in an NO-dependent manner, promotes translocation of GLUT4 storage vesicles to the sarcolemma, enhancing glucose uptake. Moreover, PGC1α is activated, enhancing mitochondrial biogenesis in skeletal muscle fibers. nNOSγ is associated with the Golgi apparatus. Moreover, a mtNOS has been postulated. The spatial organization of the different NOS compartments may be established by myoglobin, which prevents NO from diffusing between compartments. AMPK, AMP-dependent protein kinase; mtNOS, mitochondrial NOS; nNOS, neuronal NOS; NO, nitric oxide. To see this illustration in color, the reader is referred to the web version of this article at www.liebertpub.com/ars