Fluorophore-labeled myosin-specific antibodies simplify muscle-fiber phenotyping.

Skeletal muscles are frequently analyzed for composition of phenotypically distinct myofibers, as a functional determinant. We describe an improved myofiber phenotyping procedure, involving cryosection co-incubation with fluorophore-labeled myosin heavy-chain (MyHC)-isoform-specific antibodies. This technique identifies multiple fiber "types" on a single section, thereby reducing reagents and processing, and offers side-by-side comparison of samples from multiple species including mice. These advances are valuable for studying the physiological attributes of skeletal muscle in health and disease.