@article {Marsh63,
author = {Marsh, R. L. and Bennett, A. F.},
title = {Thermal dependence of contractile properties of skeletal muscle from the lizard Sceloporus occidentalis with comments on methods for fitting and comparing force-velocity curves},
volume = {126},
number = {1},
pages = {63--77},
year = {1986},
publisher = {The Company of Biologists Ltd},
abstract = {The isometric and isotonic contractile properties of fast-twitch glycolytic fibres of the iliofibularis muscle (FG-IF) in the lizard Sceloporus occidentalis were measured in vitro at 5 degrees C intervals form 10 to 40 degrees C. The mean isometric parameters at 35 degrees C, the preferred body temperature of this species, were as follows: maximum isometric force (Po), 187 +/- 8 (S.E.M.) kNm-2; ratio of twitch force to tetanic force (PTW/Po), 0.46 +/- 0.02; time to peak twitch tension (tPTW), 7.0 +/- 0.3 ms; and time from peak twitch force to 50\% relaxation (t50\%), 8.2 +/- 0.3 ms. From 20 to 35 degrees C Po was almost constant (within 8\% of the value at 35 degrees C). At 10 and 15 degrees C C. Po dropped to approximately 80\% of the value at 35 degrees C. Po was very unstable at 40 degrees C. PTW/Po was almost constant at all temperatures. The time-related isometric parameters were positively modified by temperature at all temperatures measured (Q10 greater than 1.9). The force-velocity curves of the FG-IF deviated from the simple hyperbolic relation of A. V. Hill{\textquoteright}s characteristic equation. We present two alternative equations for fitting these data. These equations resulted in residual sums of squares from nonlinear least-squares analysis that were at least seven-fold lower than those from Hill{\textquoteright}s equation. The equation that best describes our data is a hyperbola modified by the addition of a linear component: V = B(1 - P/Po)/(A + P/Po) + C(1 - P/Po). To describe the curvature of this or any other force-velocity relationship, we propose the power ratio, Wmax/VmaxPo (where Wmax is the maximum power calculated from the force-velocity relationship and Vmax is the predicted maximum velocity of shortening at zero force). Vmax of the FG-IF was 21.9LoS-1 at 35 degrees C (where Lo is muscle length). This parameter was directly related to temperature between 10 and 35 degrees C with Q10 greater than 1.8. The shape of the force-velocity curve is not influenced by temperature (Wmax/VmaxPo = 0.11).},
issn = {0022-0949},
URL = {https://jeb.biologists.org/content/126/1/63},
eprint = {https://jeb.biologists.org/content/126/1/63.full.pdf},
journal = {Journal of Experimental Biology}
}