Parameters obtained by fitting blebbistatin observations of Gm at 15 or 30 Hz to Eqs. 5 and 6
| Muscle fiber type | Group | Myosin II inhibitor | A1 | τ1 | τ1 (APs) | A2 | τ2 | τ2 (APs) | β | β (APs) |
| (µS/cm2) | (s) | (µS/cm2) | (s) | (s) | ||||||
| EDL | 15 Hz (n = 5) | Blebbistatin | −624 ± 67 | 32 ± 4 | 225 ± 30 | 6,144 ± 1,239 | 383 ± 35 | 2,680 ± 248 | 31 ± 3 | 219 ± 19 |
| EDL | 30 Hz (n = 6) | Blebbistatin | −718 ± 51 | 17 ± 1 | 256 ± 18 | 4,697 ± 523 | 161 ± 8 | 2,417 ± 127 | 13 ± 1 | 193 ± 8 |
| EDLa | 6 Hz (n = 8) | BTS | −779 ± 78 | 66 ± 8 | 199 ± 24 | 3,400 ± 431 | 1,088 ± 79 | 3,264 ± 237 | 79 ± 14 | 238 ± 43 |
| EDLa | 15 Hz (n = 18) | BTS | −809 ± 39 | 27 ± 1 | 189 ± 10 | 5,426 ± 494 | 352 ± 12 | 2,466 ± 81 | 34 ± 2 | 237 ± 12 |
| EDLa | 30 Hz (n = 13) | BTS | −706 ± 50 | 18 ± 1 | 273 ± 14 | 4,157 ± 575 | 174 ± 9 | 2,611 ± 129 | 26 ± 2 | 383 ± 37 |
| Soleus | 6 Hz (n = 5) | Blebbistatin | −441 ± 34 | 109 ± 25 | 327 ± 73 | — | — | — | — | — |
| Soleus | 15 Hz (n = 9) | Blebbistatin | −415 ± 28 | 76 ± 9 | 494 ± 60 | — | — | — | — | — |
| Soleus | 30 Hz (n = 7) | Blebbistatin | −588 ± 30 | 60 ± 9 | 897 ± 137 | — | — | — | — | — |
| Soleus | 60 Hz (n = 8) | Blebbistatin | −672 ± 12 | 35 ± 3 | 1,069 ± 93 | — | — | — | — | — |
| Muscle fiber type | Group | Myosin II inhibitor | A1 | τ1 | τ1 (APs) | A2 | τ2 | τ2 (APs) | β | β (APs) |
| (µS/cm2) | (s) | (µS/cm2) | (s) | (s) | ||||||
| EDL | 15 Hz (n = 5) | Blebbistatin | −624 ± 67 | 32 ± 4 | 225 ± 30 | 6,144 ± 1,239 | 383 ± 35 | 2,680 ± 248 | 31 ± 3 | 219 ± 19 |
| EDL | 30 Hz (n = 6) | Blebbistatin | −718 ± 51 | 17 ± 1 | 256 ± 18 | 4,697 ± 523 | 161 ± 8 | 2,417 ± 127 | 13 ± 1 | 193 ± 8 |
| EDLa | 6 Hz (n = 8) | BTS | −779 ± 78 | 66 ± 8 | 199 ± 24 | 3,400 ± 431 | 1,088 ± 79 | 3,264 ± 237 | 79 ± 14 | 238 ± 43 |
| EDLa | 15 Hz (n = 18) | BTS | −809 ± 39 | 27 ± 1 | 189 ± 10 | 5,426 ± 494 | 352 ± 12 | 2,466 ± 81 | 34 ± 2 | 237 ± 12 |
| EDLa | 30 Hz (n = 13) | BTS | −706 ± 50 | 18 ± 1 | 273 ± 14 | 4,157 ± 575 | 174 ± 9 | 2,611 ± 129 | 26 ± 2 | 383 ± 37 |
| Soleus | 6 Hz (n = 5) | Blebbistatin | −441 ± 34 | 109 ± 25 | 327 ± 73 | — | — | — | — | — |
| Soleus | 15 Hz (n = 9) | Blebbistatin | −415 ± 28 | 76 ± 9 | 494 ± 60 | — | — | — | — | — |
| Soleus | 30 Hz (n = 7) | Blebbistatin | −588 ± 30 | 60 ± 9 | 897 ± 137 | — | — | — | — | — |
| Soleus | 60 Hz (n = 8) | Blebbistatin | −672 ± 12 | 35 ± 3 | 1,069 ± 93 | — | — | — | — | — |
Experimental observations of Gm in AP-firing fibers were fitted to Eqs. 1 and 2 to obtain parameters that describe Phase 1 and Phase 2 in EDL and the reduction of Gm at the onset of AP firing in soleus. A1 represents the reduction in Gm at the onset of AP firing, whereas τ1 describes either the time required or the number of APs fired before 63% of A1 was observed. A2 represents the magnitude of the increase in Gm during Phase 2, and τ2 stands for the time or the number of APs that was fired before Gm had risen to half of A2. β reflects the steepness of the rise of Gm during Phase 2. All data are presented as means ± SEM.
Included from our companion paper (Pedersen et al., 2009).