Stretch-stimulated glucose uptake in skeletal muscle is mediated by reactive oxygen species and p38 MAP-kinase

Alternatives to the canonical insulin-stimulated pathway for glucose uptake are exercise- and exogenous reactive oxygen species (ROS)-stimulated glucose uptake. We proposed a model wherein mechanical loading, i.e. stretch, stimulates production of ROS to activate AMP-activated kinase (AMPK) to increase glucose uptake. Immunoblotting was used to measure protein phosphorylation; the fluorochrome probe 2′7′-dichlorofluorescin diacetate was used to measure cytosolic oxidant activity and 2-deoxy-d[1,2-3H]glucose was used to measure glucose uptake. The current studies demonstrate that stretch increases ROS, AMPKα phosphorylation and glucose transport in murine extensor digitorum longus (EDL) muscle (+121%, +164% and +184%, respectively; P 0.16). We also demonstrate that stretch-stimulated glucose uptake persists in the presence of the phosphatidylinositol 3-kinase (PI3-K) inhibitors wortmannin and LY294001 (P 0.99). These data indicate that stretch-stimulated glucose uptake in skeletal muscle is mediated by a ROS- and p38 MAPK-dependent mechanism that appears to be AMPKα2- and PI3-K-independent.