The temperature dependence of isometric contractions of single, intact fibres dissected from a XXXX foot muscle.

@entity19 @entity1 @entity116
1. Isometric tension responses to electrical stimulation have been studied at 7.5 37.5 degrees C in single, intact fibres of the flexor digitorum brevis muscle of the @entity19 . A large number of reproducible @entity116 could be obtained at temperatures less than or equal to 35 degrees C. 2. The tetanic force per cross-sectional area generated at 25.0 degrees C was 375 +/- 56 kPa (mean +/- S.D., n = 16). 3. The curve relating maximum tetanic tension to temperature exhibited a transition between a level of almost unaltered force (25.0-32.5 degrees C) and a marked force decline (less than or equal to 20.0 degrees C). At temperatures higher than 35.0 degrees C force production was markedly depressed and this reduction was in some cases irreversible. 4. Twitch tension showed less regular dependence on temperature; it was reduced less than tetanic tension at low temperatures. Thus, the twitch/ @entity116 tension ratio was higher at low temperatures. 5. The times for twitch contraction and for twitch half-relaxation (i) ranged from 7 to 14 ms and from 6 to 15 ms at 35.0 degrees C and (ii) exhibited Q10 values of 3.2 +/- 0.4 and 4.0 +/- 0.6, respectively. 6. It is concluded that it is possible to use intact, single fibres dissected from @entity1 skeletal muscle in physiological studies. Our results are close to previous results obtained from @entity1 muscles except that the tetanic tension per cross-sectional area was found to be higher than commonly reported.
