Table 1. Effect of TnT F88L on various... | Rockefeller University Press

Table 1.

Effect of TnT_F88L on various contractile parameters at short and long SLs

Parameter	1.9 µm		2.3 µm
Parameter	TnT_WT	TnT_F88L	TnT_WT	TnT_F88L
Maximal tension (mN ⋅ mm⁻²)	29.72 ± 1.25	31.63 ± 1.52^{^a}	49.07 ± 1.24	48.25 ± 0.93^{^a}
Tension cost (pmol ⋅ mN⁻¹ ⋅ mm⁻¹ ⋅ s⁻¹)	2.56 ± 0.17	2.34 ± 0.11^{^a}	1.26 ± 0.06	1.32 ± 0.07^{^a}
c (s⁻¹)	12.17 ± 0.42	10.98 ± 0.89^{^a}	7.95 ± 0.13	8.10 ± 0.38^{^a}
b (s⁻¹)	4.32 ± 0.09	4.19 ± 0.09^{^a}	4.33 ± 0.11	4.37 ± 0.09^{^a}
k_tr (s⁻¹)	1.99 ± 0.05	1.83 ± 0.11^{^a}	1.61 ± 0.10	1.57 ± 0.05^{^a}

Parameter	1.9 µm		2.3 µm
Parameter	TnT_WT	TnT_F88L	TnT_WT	TnT_F88L
Maximal tension (mN ⋅ mm⁻²)	29.72 ± 1.25	31.63 ± 1.52^{^a}	49.07 ± 1.24	48.25 ± 0.93^{^a}
Tension cost (pmol ⋅ mN⁻¹ ⋅ mm⁻¹ ⋅ s⁻¹)	2.56 ± 0.17	2.34 ± 0.11^{^a}	1.26 ± 0.06	1.32 ± 0.07^{^a}
c (s⁻¹)	12.17 ± 0.42	10.98 ± 0.89^{^a}	7.95 ± 0.13	8.10 ± 0.38^{^a}
b (s⁻¹)	4.32 ± 0.09	4.19 ± 0.09^{^a}	4.33 ± 0.11	4.37 ± 0.09^{^a}
k_tr (s⁻¹)	1.99 ± 0.05	1.83 ± 0.11^{^a}	1.61 ± 0.10	1.57 ± 0.05^{^a}

Maximal tension was measured by exposing muscle fibers to saturating Ca²⁺ concentration (pCa 4.3) in a constantly stirred chamber. Tension cost was derived from the ATPase/tension relationship, as previously described (de Tombe and Stienen, 1995; Chandra et al., 2015). Parameters c and b were estimated by fitting the NLRD model to the force response phases to various amplitude stretch/release perturbations (Fig. 1; Ford et al., 2010). c represents the rate of force decay to a minimum force point following a sudden stretch in ML, and b represents the rate at which force rises at the new ML. k_tr was estimated by fitting a monoexponential function to the rising phase of the force response to a large slack-restretch length maneuver and represents the rate of tension redevelopment (Brenner and Eisenberg, 1986). Estimates from several muscle fibers per group were averaged and presented as mean ± SEM. Statistical differences were analyzed using two-way ANOVA and subsequent post hoc multiple pairwise comparisons (Fisher’s LSD method). The number of fibers measured (from three hearts) for all groups was 10.

Not significantly different from TnT_WT fibers.

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