The temperature dependence of post-vibration tension recovery in intact and skinned rat tracheal smooth muscle

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Abstract
The contraction kinetics of rat tracheal smooth muscle were studied by analysing the time course of tension recovery after the cessation of a 2 s length vibration (100 Hz, sinusoidal) in activated preparations. An initial fast component of tension recovery reflects the rearrangement of those crossbridges previously detached by vibration. The subsequent slow component could be related to the kinetics of the regular actin-myosin interaction. Both components still occur independently of the duration and type of activation (electrical field stimulation and 0.1 mM1−1 acetylcholine), the bath temperature (16, 28 and 37° C), and of the functional behaviour of the cell membrane (intact or Triton X-100 skinned preparations). The time constants of post-vibration tension recovery were increased distinctly during prolonged activation, low temperature, and after skinning (lack of calmodulin). The activation enthalpy was calculated according to Arrhenius by using the time constant of the slow component of post-vibration tension recovery. It amounted to 94.7 ±0.6 kJ mol−1 for the intact preparation and 97.2 ±1.0 kj mol−1 for the skinned one (temperature range 16–28° C). These results provide further evidence that vibration affects the contractile system directly and that the kinetics of post-vibration tension recovery reflect the kinetics of actin-myosin interaction.