Fig. 5. The MLC3/MLC1 ratio increased in proportion to the percentage of type 1 MHC in single fibres, but was highly variable within fibre types. (A) MLC3/MLC1 ratio and MHC isoforms were measured in single type 1, type 1-2 and type 2 fibres by quantitative densitometry of gels after SDS-PAGE. Fibres (N=100) were obtained from the anterior tibialis (AT), cruralis (CR), gluteal (GL), gracilis (GR), semimembranosus (SM) and sartorius (SA) muscles. Each symbol corresponds to a different muscle. Linear regression showed that the MLC3/MLC1 ratio increased in direct proportion to the percentage of type 1 MHC. There was substantial variability in MLC3/MLC1 ratio within each fibre type, and the highest values were all found in the GR muscle. (B) MLC3/MLC1 ratio for fibres that contained MLC1x (N=16; data are subset of A). The relationship between the MLC3/MLC1 ratio and percentage of type 1 MHC was similar to A, and the full range of fibre types was represented.
