Fig. 2.

Evaluation of the T-tubule system of UNI and ALT myofibers. a, b Representative confocal images of a UNI myofiber (a) or an ALT myofiber (b) stained with di-8-ANEPPS to visualize the sarcolemma and T-tubules. Scale bars in a, b are 10 μm. c, d Bottom panels are zoom-in versions of boxed regions indicated in panels a and b. Traces inserted in zoomed-in images are averaged fluorescence profiles across the box, scale bars: 5 μm. In control UNI myofibers (n = 18, N = 3), T-tubules are organized in a regular striated pattern. No changes in T-tubule morphology are seen in ALT myofibers (n = 16, N = 3). N indicates number of mice per condition, and n indicates number of myofibers imaged