Table 1.
ktr, b, ATPase and pCa50 (ATPase) values in NTG (α-Tm) and TG (β-Tm) fibres
| McTnTWT | McTnT1-44Δ | McTnT45-74Δ | |
|---|---|---|---|
| NTG (α-Tm) | |||
| ktr (s−1) | 12.87 ± 0.46 (14) | 14.18 ± 0.47 (13) | 14.05 ± 0.56 (14) |
| b (s−1) | 31.81 ± 1.41 (12) | 34.88 ± 3.20 (7) | 33.83 ± 1.61 (13) |
| ATPase (pmol mm−3 s−1) | 304.38 ± 9.36 (14) | 225.33 ± 10.67 (13)*** | 303.79 ± 7.97 (14) |
| pCa50 (ATPase) | 5.69 ± 0.02 (11) | 5.58 ± 0.03 (12)** | 5.99 ± 0.03 (7)*** |
| TG (β-Tm) | |||
| ktr (s−1) | 12.58 ± 0.50 (12) | 13.84 ± 0.65 (14) | 13.86 ± 0.52 (14) |
| b (s−1) | 31.94 ± 1.33 (14) | 35.42 ± 1.63 (7) | 34.79 ± 1.13 (12) |
| ATPase (pmol mm−3 s−1) | 258.01 ± 3.77 (10) | 224.16 ± 8.31 (14)*** | 278.02 ± 8.44 (14) |
| pCa50 (ATPase) | 5.74 ± 0.01 (8) | 5.71 ± 0.01 (10) | 6.18 ± 0.02 (7)*** |
The rate of tension redevelopment (ktr) was determined using a large release and restretch protocol (Brenner & Eisenberg, 1986). The rate of XB recruitment (b) was determined by fitting the NLRD model to the force responses elicited by step-like changes in ML (Ford et al. 2010). The Hill equation was fitted to the normalized pCa–ATPase relationships to derive pCa50 (ATPase) values. The number of determinations for each group is presented in the brackets beside each estimate. Values are reported as mean ± SEM. **P < 0.005; ***P < 0.001 when compared with McTnTWT within the respective groups. McTnT, mouse cardiac troponin T; McTnTWT, wild-type mouse cardiac troponin T; NTG, non-transgenic; TG, transgenic; Tm, tropomyosin.