Temperature-induced changes in the force-velocity curve of rabbit papillary muscle are the net result of an inotropic temperature effect and a specific temperature effect with a Q10 of 1.9.
Abstract The force‐velocity relationship was determined at the moment of isometric peak twitch force in rabbit papillary muscles using the damped‐release technique described previously. The analysis was carried out in each muscle at two or three temperatures within the range 22–338deg; C. The experimental data were fitted with Hill's equation by means of a computer program using the least squares method. Lowering of the temperature caused an increase of the isometric peak twitch force (Po) and also, generaliy, an increase of the extrapolated value of V max (the shortening velocity at zero load). The temperature‐induced changes of the force‐velocity curve were interpreted as being the net result of two opposing effects: I. an altered degree of activation of the contractile system caused by a change in the amount of activator‐calcium bound to the contractile proteins ( ‘inotropic temperature effect’ ), and 2. a change in the rate of interaction between the A and I filaments independent of the degree of activation ( ‘specific temperature effect’ ). The analysis indicated a Q10 of 1.9 for the specific temperature effect. This value accords with the temperature dependence of V max that has been observed during tetanic contraction of skeletal muscle.
Edman et al. (Mon,) studied this question.