Parameters obtained from stretch and ATP step experiments at different pH
| . | pH 6.7, control . | pH 7.2 . | pH 7.4 . | pH 7.7 . |
|---|---|---|---|---|
| Stretch experiments | ||||
| t2 (ms) | 454±60 (17) | 639±89 (4) | 803±84 (6) | 1059±104 (7) |
| t3 (ms) | 1127±105 (17) | 1596±126 (4) | 1756±117 (6) | 2040±131 (7) |
| ATP step experiments | ||||
| ΔTfast decay (%) | 44.8±7.2 (5) | - | 65.5±8.3 (7) | - |
| rslow decay (% min−1) | 2.0±0.1 (5) | - | 2.2±0.1 (5) | - |
| τfast decay (ms) | 495±90 (5) | - | 478±70 (7) | - |
| t½fast decay (ms) | 331±42 (5) | - | 319±37 (7) | - |
| τforce rise (ms) | 590±43 (7) | - | 1339±502 (7) | - |
| t½force rise (ms) | 441±48 (7) | - | 1024±125 (7) | - |
| . | pH 6.7, control . | pH 7.2 . | pH 7.4 . | pH 7.7 . |
|---|---|---|---|---|
| Stretch experiments | ||||
| t2 (ms) | 454±60 (17) | 639±89 (4) | 803±84 (6) | 1059±104 (7) |
| t3 (ms) | 1127±105 (17) | 1596±126 (4) | 1756±117 (6) | 2040±131 (7) |
| ATP step experiments | ||||
| ΔTfast decay (%) | 44.8±7.2 (5) | - | 65.5±8.3 (7) | - |
| rslow decay (% min−1) | 2.0±0.1 (5) | - | 2.2±0.1 (5) | - |
| τfast decay (ms) | 495±90 (5) | - | 478±70 (7) | - |
| t½fast decay (ms) | 331±42 (5) | - | 319±37 (7) | - |
| τforce rise (ms) | 590±43 (7) | - | 1339±502 (7) | - |
| t½force rise (ms) | 441±48 (7) | - | 1024±125 (7) | - |
Values are means ± s.d. (N).
Parameters obtained from stretch experiments: t2, time from the beginning of stretch to the onset of delayed force increase; t3, time from the beginning of stretch to the peak of delayed force increase.
Parameters obtained from ATP step experiments: ΔTfast decay, extent of force decay within the initial rapid phase; rslow decay, the rate of force decay per min within the slow (almost linear) phase; τfast decay, t½fast decay, time constant and half-time, respectively, of force decay in the initial rapid phase;τ force rise, t½force rise, time constant and halftime, respectively, of force rise.
Significances for statistic differences: t2 and t3, P<0.01 for each test condition against control condition (paired Student-t-tests); τforce rise, t½force rise andΔ Tfast decay, P<0.01 for test and control condition (unpaired Student's t-tests); rslow decay, P<0.05 for test and control condition (unpaired Student's t-tests). The time parameters τfast decayand t½fast decay are not significantly different between test and control condition (P>0.23, unpaired Student's t-test).