Mechanical and energetic parameters of myofibrils and skinned trabeculae from WT and Obscn KO mice
| Myofibril . | RT . | Po . | kACT . | kTR . | Dslow . | Slow kREL . | Fast kREL . |
|---|---|---|---|---|---|---|---|
| mN mm−2 | mN mm−2 | s−1 | s−1 | ms | s−1 | s−1 | |
| WT (N = 5) | 11 ± 1.3 (n = 19) | 108 ± 12 (n = 27) | 9.1 ± 0.69 (n = 32) | 8.6 ± 0.92 (n = 24) | 78.5 ± 6.0 (n = 19) | 1.62 ± 0.28 (n = 19) | 25 ± 3 (n = 19) |
| Obscn KO (N = 3) | 14.6 ± 2.3 (n = 27) | 92 ± 11 (n = 28) | 10.2 ± 0.7 (n = 21) | 9.8 ± 0.9 (n = 26) | 73.6 ± 4.4 (n = 16) | 1.62 ± 0.10 (n = 16) | 20.4 ± 2.7 (n = 20) |
| Skinned trabeculae | Po | pCa50 | Actomyosin ATPase activity | Tension cost | |||
| mN mm−2 | mN mm−2 | pmol*µl−1*s−1 | pmol*µl−1*s−1/mN mm−2 | ||||
| WT (N = 3) | 31 ± 4 (n = 9) | 5.93 ± 0.03 (n = 9) | 685 ± 89.8 (n = 9) | 22.4 ± 1.12 (n = 9) | |||
| Obscn KO (N = 3) | 30 ± 2.3 (n = 7) | 5.91 ± 0.03 (n = 7) | 583 ± 96.3 (n = 7) | 19.5 ± 2.87 (n = 7) |
| Myofibril . | RT . | Po . | kACT . | kTR . | Dslow . | Slow kREL . | Fast kREL . |
|---|---|---|---|---|---|---|---|
| mN mm−2 | mN mm−2 | s−1 | s−1 | ms | s−1 | s−1 | |
| WT (N = 5) | 11 ± 1.3 (n = 19) | 108 ± 12 (n = 27) | 9.1 ± 0.69 (n = 32) | 8.6 ± 0.92 (n = 24) | 78.5 ± 6.0 (n = 19) | 1.62 ± 0.28 (n = 19) | 25 ± 3 (n = 19) |
| Obscn KO (N = 3) | 14.6 ± 2.3 (n = 27) | 92 ± 11 (n = 28) | 10.2 ± 0.7 (n = 21) | 9.8 ± 0.9 (n = 26) | 73.6 ± 4.4 (n = 16) | 1.62 ± 0.10 (n = 16) | 20.4 ± 2.7 (n = 20) |
| Skinned trabeculae | Po | pCa50 | Actomyosin ATPase activity | Tension cost | |||
| mN mm−2 | mN mm−2 | pmol*µl−1*s−1 | pmol*µl−1*s−1/mN mm−2 | ||||
| WT (N = 3) | 31 ± 4 (n = 9) | 5.93 ± 0.03 (n = 9) | 685 ± 89.8 (n = 9) | 22.4 ± 1.12 (n = 9) | |||
| Obscn KO (N = 3) | 30 ± 2.3 (n = 7) | 5.91 ± 0.03 (n = 7) | 583 ± 96.3 (n = 7) | 19.5 ± 2.87 (n = 7) |
Data are means ± SE; N, number of mice in the group; n, number of myofibrils/skinned trabeculae; RT, resting tension; Po, maximal Ca2+-activated tension; Dslow, slow-phase duration. In skinned trabeculae, pCa50 (50% of maximal Ca2+-dependent tension), maximal (actomyosin) ATPase activity, and tension cost (actomyosin ATPase activity/tension) were measured. Statistical tests for all measurements: one-way ANOVA with Tukey’s correction. *P < 0.05; **P < 0.01.