FIG. 4.

Oxidative fiber in skeletal muscle. A: Vastus lateralis muscle. The tissue was isolated from mice that were fed high-fat diet for 13 weeks. B: Oxidative fiber (type I fibers) in serial cryostat sections of muscle. The muscle tissue slides were made from vastus lateralis, gastrocnemius (gastr.), and soleus muscle. They were stained with antibody against type I myosin heavy chain for oxidative fibers, as indicated by the brown color. The photograph was taken at ×20 magnification. C: Succinate dehydrogenase staining of oxidative fibers. The oxidative fibers were stained in serial cryostat sections of the vastus lateralis and gastrocnemius (gastr.) muscle as indicated by dark blue color in the photomicrograph. D and E: Quantification of proteins in immunoblot. The whole-cell lysate was prepared from muscle tissues and analyzed in an immunoblot. Signals for PGC-1α, type I myosin heavy chain, myoglobin, phosphorylated AMPK (pAMPK), and phosphorylated p38 (pP38) were blotted with specific antibodies. A representative blot is shown. Relative signal strength was quantified for each band and expressed in the bar figure. Results are the means ± SE (n = 8 mice). *P < 0.01, **P < 0.001 (vs. control). (A high-quality digital representation of this figure is available in the online issue.)