Fig. 8. Impaired force generation by Tln1-deficient muscles. (A) The
length, mass and physiological cross-sectional area (PCSA) are similar in the
fifth EDL muscle from wild-type and Tln1HSA-CREko mice.
(B,C) Sample curves representing a single isometric and
eccentric contraction, respectively. (D-H) Isometric and eccentric
contractile properties of the fifth EDL muscle isolated from 2- and
7-month-old mice. (D) No significant difference was observed in stress exerted
by 2-month-old muscles from wild-type and Tln1HSA-CREko mice in the
eccentric contraction protocol. (E) Example of force profile of the first
isometric contraction in 7-month-old mice. Tln1-deficient muscles
exert reduced isometric stress. (F,G) In an eccentric contraction protocol,
muscles from 7-month-old Tln1HSA-CREko mice showed a significant
reduction in peak stress exerted in the pre-eccentric (P=0.0276) and
post-eccentric (P=0.0358) isometric contractions as compared with
wild-type controls (n
4 per genotype per time point). (H) Even
though Tln1-deficient muscles generated less force than controls, the
force drop was comparable between genotypes, suggesting enhanced
susceptibility to damage in the mutants. All force values were normalized
against the PCSA of the muscle (mean ±s.e.).