Table 1.
Characterization of scallop muscle fiber bundles
| Fiber preparation | Total RLC/ELC (±SEM) | Tension Ca sensitivity* (±SEM) | Myofibril ATPase Ca sensitivity* (±SD) |
|---|---|---|---|
| Control | 0.87 ± 0.03 | 0.95 ± 0.01 | 0.97 ± 0.01 |
| (n = 14) | (n = 23) | (n = 6) | |
| Extracted | 0.21 ± 0.02 | 0.13 ± 0.19 | 0.28 ± 0.07 |
| (n = 16) | (n = 7) | (n = 4) | |
| Labeled | 0.86 ± 0.05 | 0.91 ± 0.06 | 0.93 ± 0.02 |
| (n = 13) | (n = 17) | (n = 6) |
*
Isometric tension and myofibril ATPase were measured (35) under EPR relaxation and contraction conditions. Ca sensitivity is [1 − (relaxation/contraction)]. Active tension was similar for control and labeled fibers and was in the range of 1–2.5 N/cm2, as previously reported for scallop fiber bundles (30). The essential light chain (ELC) is not removed by the extraction procedure, so the ratio of RLC/ELC, determined from urea/polyacrylamide gels, reflects the RLC content.