Figure 1

Typical force traces, maximal tension, submaximal tension, relative submaximal tension, and specialized SDS-PAGE gel example. (A) Typical force trace of a slow-twitch single muscle fiber of a control subject and of a muscle fiber bundle of a NEB-NM patient (biopsy ID T33 is shown) during exposure to an experimental solution with pCa 4.5. Note the severely reduced maximal tension of the muscle fibers of the NEB-NM patient. (B) Maximal tension (pCa 4.5) of muscle fibers of healthy controls and NEB-NM patients. (C) Submaximal tension (pCa 5.8) of muscle fibers of healthy controls and NEB-NM patients. (D) Relative submaximal tension (pCa 5.8/4.5). Note that the relative submaximal tension of muscle fibers of NEB-NM patients is reduced, indicating a reduced calcium sensitivity of force. (E) Example of a specialized SDS-PAGE gel that was used to determine the myosin heavy chain isoform composition of the muscle fiber preparations that we used in our contractility experiments. Here, the bundle from NEB-NM T33 is composed of type 1 myosin heavy chain isoforms (MHC 1), the bundle from NEB-NM T887 contains both MHC 1 and type 2A myosin heavy chain isoforms (MHC 2A), and the marker exhibits both MHC 1 and MHC 2A as myosin 2X isoforms (MHC 2X). NEB-NM, nemaline myopathy patients with mutations in the nebulin gene; NS, not significant. *P < 0.05.