Effects of PKA treatment on mechanical properties in WT, cTnIAla5, cMyBP-C−/−, and cTnIAla5/cMyBP-C−/− skinned myocardium
| Treatment group | Resting force | Maximum Ca2+- activated force | Hill coefficient (nH) | Ca2+ sensitivity of force (pCa50) | Maximum rate of force redevelopment | Minimum rate of force redevelopment |
| mN/mm2 | mN/mm2 | s−1 | s−1 | |||
| WT (n = 16) | ||||||
| (−) PKA (n = 8) | 0.66 ± 0.07 | 14.43 ± 1.43 | 4.19 ± 0.15 | 5.82 ± 0.01 | 26.63 ± 0.88 | 2.22 ± 0.25 |
| (+) PKA(n = 8) | 0.54 ± 0.08 | 12.62 ± 1.37 | 4.21 ± 0.15 | 5.69 ± 0.01a | 27.98 ± 1.31 | 2.60 ± 0.12 |
| cTnIAla5 (n = 16) | ||||||
| (−) PKA (n = 8) | 0.89 ± 0.12 | 12.87 ± 1.03 | 5.03 ± 0.19b | 5.48 ± 0.01b | 22.00 ± 1.30b | 2.51 ± 0.24 |
| (+) PKA (n = 8) | 0.99 ± 0.20 | 15.07 ± 2.65 | 4.09 ± 0.18a | 5.40 ± 0.01a | 23.23 ± 1.06 | 3.95 ± 0.26a |
| cMyBP-C−/− (n = 16) | ||||||
| (−) PKA (n = 8) | 0.95 ± 0.12b | 15.68 ± 1.67 | 3.95 ± 0.08 | 5.83 ± 0.01 | 34.48 ± 1.96b | 3.66 ± 0.20b |
| (+) PKA (n = 8) | 0.67 ± 0.12 | 14.30 ± 1.21 | 3.59 ± 0.09a | 5.74 ± 0.01a | 34.09 ± 1.87 | 4.00 ± 0.11 |
| cTnIAla5/cMyBP-C−/− (n = 16) | ||||||
| (−) PKA (n = 8) | 1.23 ± 0.17b | 13.97 ± 1.40 | 4.25 ± 0.17 | 5.46 ± 0.01b | 35.39 ± 1.66b | 5.14 ± 0.43b |
| (+) PKA (n = 8) | 1.23 ± 0.27 | 16.8 ± 2.47 | 4.23 ± 0.23 | 5.45 ± 0.01 | 34.34 ± 2.26 | 5.35 ± 0.70 |
| Treatment group | Resting force | Maximum Ca2+- activated force | Hill coefficient (nH) | Ca2+ sensitivity of force (pCa50) | Maximum rate of force redevelopment | Minimum rate of force redevelopment |
| mN/mm2 | mN/mm2 | s−1 | s−1 | |||
| WT (n = 16) | ||||||
| (−) PKA (n = 8) | 0.66 ± 0.07 | 14.43 ± 1.43 | 4.19 ± 0.15 | 5.82 ± 0.01 | 26.63 ± 0.88 | 2.22 ± 0.25 |
| (+) PKA(n = 8) | 0.54 ± 0.08 | 12.62 ± 1.37 | 4.21 ± 0.15 | 5.69 ± 0.01a | 27.98 ± 1.31 | 2.60 ± 0.12 |
| cTnIAla5 (n = 16) | ||||||
| (−) PKA (n = 8) | 0.89 ± 0.12 | 12.87 ± 1.03 | 5.03 ± 0.19b | 5.48 ± 0.01b | 22.00 ± 1.30b | 2.51 ± 0.24 |
| (+) PKA (n = 8) | 0.99 ± 0.20 | 15.07 ± 2.65 | 4.09 ± 0.18a | 5.40 ± 0.01a | 23.23 ± 1.06 | 3.95 ± 0.26a |
| cMyBP-C−/− (n = 16) | ||||||
| (−) PKA (n = 8) | 0.95 ± 0.12b | 15.68 ± 1.67 | 3.95 ± 0.08 | 5.83 ± 0.01 | 34.48 ± 1.96b | 3.66 ± 0.20b |
| (+) PKA (n = 8) | 0.67 ± 0.12 | 14.30 ± 1.21 | 3.59 ± 0.09a | 5.74 ± 0.01a | 34.09 ± 1.87 | 4.00 ± 0.11 |
| cTnIAla5/cMyBP-C−/− (n = 16) | ||||||
| (−) PKA (n = 8) | 1.23 ± 0.17b | 13.97 ± 1.40 | 4.25 ± 0.17 | 5.46 ± 0.01b | 35.39 ± 1.66b | 5.14 ± 0.43b |
| (+) PKA (n = 8) | 1.23 ± 0.27 | 16.8 ± 2.47 | 4.23 ± 0.23 | 5.45 ± 0.01 | 34.34 ± 2.26 | 5.35 ± 0.70 |
Data are means ± SEM. Resting force was measured at pCa 9.0. Maximum force and the apparent rate constant of force redevelopment (ktr) were measured at pCa 4.5. Minimum ktr was measured at ∼10% of maximum force. pCa50 and nH values were derived by fitting the force–pCa relationships to a Hill equation described in Materials and methods.
Significantly different from values recorded in untreated (−PKA) skinned myocardial preparations.
Significantly different from values recorded in untreated (−PKA) WT skinned myocardial preparations.