| Autor: |
Peiper, Ulrich, Zobel, Kuno, Bode, D., Donker, E., Wucherpfennig, M. |
| Zdroj: |
Pflügers Archiv: European Journal of Physiology; 1987, Vol. 408 Issue 4, p373-378, 6p |
| Abstrakt: |
In isolated rat tracheal smooth muscle, contraction was induced by electrical field stimulation (= EL; frequency = 30 Hz; pulse duration = 0.17 ms), 10 μmol/l acetylcholine (= ACh), potassium depolarization (137 mmol/l K), or by 10 mmol/l barium (= BA). Contraction kinetics were studied by analyzing tension recovery after cessation of a 1.8s length vibration (100 Hz sinusoida; amplitude = 6% of the muscle length). The contraction speed was high during EL as can be seen from the short time constant of post-vibration tension recovery (τ=5.90±0.14 s) found 30 s after onset of stimulation. The time constants of tension recovery during long-term (50 min) activation averaged 12.88±0.32 s (K) and 13.24±0.17 s (ACh) when the vibration was stopped 8-45 min after onset of activation. As both of these stimuli act mainly via cholinergic receptors, similar down-regulated contraction kinetics occur under steady-state conditions of tonic contraction. However, during barium activation steady-state conditions need a 45 min agonist incubation, and the time constant of post-vibration tension recovery was extended to 34.05±2.21 s. Thus, calcium may be replaced by barium in the force generation process but it produces slower cycling of cross-bridges. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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