Table 1. Tension generation and relaxation in ventricular myofibrils from wild-type (WT) and myopalladin knockout (MKO) male mice.
| Myofibril batch | Resting conditions | Tension generation | Relaxation | |||||
|---|---|---|---|---|---|---|---|---|
| Slow phase | Fast phase | |||||||
| SL(µm) | RT(mN/mm2) | P0(mN/mm2) | kACT(s–1) | Duration(ms) | kREL(s–1) | kREL(s–1) | ||
| WT | 2.22 ± 0.02 (26) | 11.1 ± 1.4 (26) | 161 ± 11 (26) | 5.17 ± 0.29 (23) | 74 ± 4 (20) | 1.96 ± 0.18 (20) | 47 ± 4 (23) | |
| MKO | 2.21 ± 0.01 (27) | 10.3 ± 1.3 (26) | 112 ± 6***(27) | 5.38 ± 0.40 (26) | 72 ± 3 (22) | 2.03 ± 0.15 (19) | 30 ± 4 (24) | |
All values are presented as mean ± standard error of the mean (SEM). Numbers in parentheses are number of myofibrils. SL, sarcomere length, RT, resting tension, P0, maximum isometric tension; kACT, rate constant of tension rise following step-wise pCa decrease (8.0→4.5) by fast solution switching. Full tension relaxation kinetics were characterized by the duration and rate constant of tension decay of the isometric slow relaxation phase (slow kREL) and the rate constant of the fast relaxation phase (fast kREL). ***p < 0.001 vs. WT; unpaired Student’s t-test.