Fig. 8. Predominant isoforms in muscle samples (single fibers and bundles of
fibers) classified by the myosin heavy chain (MHC) proteins present in the
samples (S1, S2 or both MHC proteins). (A) The relative
proportion of S1 MHC mRNA was significantly higher in muscles with
the S1 MHC protein or both S1 and S2 proteins
than in samples possessing only the S2 MHC protein. Unexpectedly,
samples characterized by the S2 MHC at the protein level still
expressed 
30% of their MHC mRNA as the S1 isoform (70%
S2 MHC). (B) S1 fibers expressed significantly more
troponin (Tn) T as the T3 protein, while mixed samples and those
with only the S2 MHC expressed significantly less T3
(more TnT1). (C) TnI2 was the predominant TnI isoform in
the S2 fibers, while (D) TnI3 was the major isoform in
S1 fibers. Differences were analyzed by ANOVA, and a Bonferroni
post-hoc test was used to determine which means were significantly
different from one another (represented by different lowercase letters).
Values are means ± S.D. [N=21 total samples:
S1=10 (single fibers), both=3 (fiber bundles), S2=8 (6
single fibers, 2 fiber bundles)].