Table A2.
Cell shortening model parameters fit to 6-mo-old midmyocardial cell measurements
| Value | Units | Description | |
|---|---|---|---|
| Markov model parameters | |||
| kCa+ | 350 | μM−1 · s−1 | TnC-Ca binding rate |
| kCa− | 1.15e3 | s−1 | TnC-Ca dissociation rate |
| kB+ | 3.00e5 | s−1 | Tropomyosin nonpermissive to permissive transition rate |
| kB− | 330 | s−1 | Tropomyosin permissive to nonpermissive transition rate |
| γB | 350 | Interregulatory unit cooperativity coefficient | |
| q | 0.5 | Forward-reverse weighting coefficient for kinetic effects of cooperativity | |
| pf | 0.25 | RLC phosphorylation effect coefficient for cross-bridge binding | |
| ϵBS | 2.00e-3 | N/m | Baseline myosin stiffness |
| ϵRLCP | 2.20e-3 | N/m | Myosin stiffness under RLC phosphorylation |
| T | 298 | K | Temperature |
| f | 200 | s−1 | Cross-bridge binding rate |
| g | 70.0 | s−1 | Cross-bridge dissociation rate (prepower-stroke) |
| hf | 2.38e3 | s−1 | Cross-bridge forward power-stroke rate |
| hb | 306 | s−1 | Cross-bridge reverse power-stroke rate |
| gxb | 225 | s−1 | Cross-bridge detachment rate (postpower-stroke) |
| ξ | 2.84 | Universal cross-bridge kinetic scaling coefficient | |
| Qp | 0.54 | Fractional phosphorylation of RLC at baseline | |
| Cross-bridge distortion and strain dependence parameters | |||
| xpo0 | 7.00e-9 | m | Cross-bridge distortion induced by power-stroke |
| σ+ | 8.03 | Cross-bridge detachment strain modifier for negative distortion values | |
| σ− | 3.90 | Cross-bridge detachment strain modifier for positive distortion values | |
| σh | 6.00 | Cross-bridge forward power-stroke strain-dependent modifier | |
| Cell mechanics parameters | |||
| η | 1.92e9 | N · s · m−1 | Myocyte viscous constant |
| kp | 1.07e5 | N/m2 | Scaling coefficient for nonlinear myocyte stiffness |
| τp | 5.22 | Exponential coefficient for nonlinear myocyte stiffness | |
| SLslack | 1.8 | μm | Slack sarcomere length |
| Nxb | 1e17 | m−2 | Cross bridges per unit cross-sectional area |