Enhancement of twitch force by stretch in a nerve-skeletal muscle preparation of the frog Rana porosa brevipoda and the effects of temperature on it.
2004
SUMMARY We investigated the mechanism of the enhancement of twitch force by stretch
and the effects of temperature on it in nerve-skeletal muscle preparations of
whole iliofibularis muscles isolated from the frog Rana brevipoda .
When a preparation was stimulated indirectly and stretched, the twitch force
after the stretch was enhanced remarkably in comparison to that observed
before a stretch at low temperature. The enhanced force obtained by a stretch
of 20% resting muscle length ( l 0 ) at low temperature was
as high as the force obtained by direct stimulation. The phenomenon was not
dependent on the velocity but on the amplitude of stretch. The enhanced force
obeyed the length-force relationship when a stretch was long enough. The above
results were observed when the frogs were kept at room temperature
(20-22°C). Measurements were also taken at low temperature (4°C); when
frogs were kept at low temperature for more than 2 months, twitch force
obtained without stretch was considerably higher at l 0 .
The amplitude of the action potential recorded extracellularly from the muscle
surface increased remarkably after a stretch, but was same before and after a
stretch when recorded from the nerve innervating muscle. The effects of
temperature on twitch and tetanic force by direct or indirect stimulation
without stretch were also studied as basic data of the stretch experiment. The
results from this study suggest that stretch-induced force enhancement in a
nerve-muscle preparation is caused by an increase in the transmission rate
between nerve and muscle, and the amplitude of the enhanced force is
determined by the length-force relationship of the muscle. The phenomenon is
also strongly affected by the temperature at which the frogs are kept.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
42
References
5
Citations
NaN
KQI