| Property . | Force (15°C) . | Δ[Ca2+] (16°C) . |
|---|---|---|
| 10–100% rise time (ms) | 6.1 ± 0.3 (5) | 0.9 ± 0.0 (8) |
| FDHM (ms) | 10.9 ± 0.2 (5) | 1.9 ± 0.1 (8) |
| Peak amplitude | 1.6 ± 0.2 kN/m2 (5) | 5.7 ± 0.4 μM (8) |
| Property . | Force (15°C) . | Δ[Ca2+] (16°C) . |
|---|---|---|
| 10–100% rise time (ms) | 6.1 ± 0.3 (5) | 0.9 ± 0.0 (8) |
| FDHM (ms) | 10.9 ± 0.2 (5) | 1.9 ± 0.1 (8) |
| Peak amplitude | 1.6 ± 0.2 kN/m2 (5) | 5.7 ± 0.4 μM (8) |
The entries are mean ± SEM values (number of experiments). In the second column, peak amplitude has been referenced to the cross-sectional area of the bundle; in the third column, Δ[Ca2+] was estimated from the Mag-fluo-4 ΔF/FR referenced to the myofibrillar region of the fiber (see Materials and methods). Of the eight fibers that contributed to the data in the third column, four appeared to have Δ[Ca2+] signals whose falling phase was free of a movement artifact, and four appeared to have a small negative-going movement artifact at 7–12 ms (as in Fig. 1 E). A slightly briefer value of FDHM was observed for the latter fibers compared with the former, 1.8 ± 0.1 vs. 2.0 ± 0.1 ms; this indicates that the movement artifact may have artifactually reduced the estimate of FDHM by a small amount.