Table 1.
Effect of TnTA30V on dynamic contractile parameters in α- and β-MHC fibers
| α-MHC |
β-MHC |
|||
|---|---|---|---|---|
| TnTWT | TnTA30V | TnTWT | TnTA30V | |
| c, s−1 | 47.09 ± 1.67 | 43.48 ± 2.49 | 19.32 ± 0.99 | 20.61 ± 1.26 |
| b, s−1 | 34.74 ± 1.94 | 33.64 ± 1.91 | 12.00 ± 0.51 | 11.30 ± 0.43 |
| γ, s−1 | 58.00 ± 5.52 | 55.59 ± 4.41 | 42.02 ± 2.36 | 42.21 ± 3.61 |
| ktr, s−1 | 12.25 ± 0.49 | 12.42 ± 0.44 | 5.77 ± 0.21 | 5.31 ± 0.26 |
Data for each group are expressed as means ± SE. Rate parameters, c, b, and γ, were estimated by fitting the nonlinear recruitment distortion model to the family of force responses to various amplitude step-like length perturbations (18). ktr was estimated by fitting a monoexponential function to the force response to a large release-restretch procedure, as described in materials and methods. Statistical differences were analyzed for mouse troponin-T equivalent of the human A28V mutation (TnTA30V) relative to wild-type mouse troponin T (TnTWT), using two-way ANOVA and post hoc Fisher’s least significant differences tests. For a given myosin heavy chain (MHC) isoform, none of the parameters listed in the table were significantly different between TnTA30V and TnTWT. The number of fibers measured (from 3 hearts) were as follows: TnTWT + α-MHC (n = 12), TnTA30V + α-MHC (n = 14), TnTWT + β-MHC (n = 11), and TnTA30V + β-MHC (n = 12).