The Influence of Temperature on the Force‐Velocity Relationship in Rabbit Papillary Muscle

Abstract

EDMAN, K. A. P., ALICIA MATTIAZZI and E. NILSSON. T h e influence of ternperature on the force-velocity relationship in rabbit papillary muscle. Acta physiol. scand. 1974. 90. 750-756. T h e 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 o r three temperatures within the range 22-33" C. T h e experimental data were fitted with Hill's equation by means of a computer pmgram using the least squares method. Lowering of the temperature caused a n increase of the isometric peak twitch force (Po) and also, generaliy, an increase of the extrapolated value of V,,,, (the shortening velocity a t zero load). T h e 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 cffect') , and 2. a change in the rate of interaction between the A and I filaments independent of the degree of activation ('specific temperature effect'). T h e analysis indicated a Q i o of 1.9 for the specific temperature effect. This value accords with the temperature dependence of \',,,:,x that has been observed during tetanic contraction of skeletal muscle.

Excitation–Contraction Coupling in the Goldfish (Carassius auratus) Intact Heart

“…If the AP is shorter, then the duration of the L-type Ca 2+ current is also shorter and less Ca 2+ is brought into the cell. A very similar temperature dependency has been reported in other species ( Edman et al, 1974 ; Mattiazzi and Nilsson, 1976 ), in which the mechanical activity and the force–velocity relationship were measured in rabbit papillary muscle. The authors conclude that the observed decrease in contractility cannot be solely related to a decrease in the duration of Ca 2+ release, but may also be related to an increase in the rate of Ca 2+ sequestration by the SR.…”

Time and calcium dependence of activation and inactivation of calcium-induced release of calcium from the sarcoplasmic reticulum of a skinned canine cardiac Purkinje cell.

“…3, A and C) . This is consistent with the increase of peak isometric force observed in intact mammalian cardiac preparations at low temperature (Kruta, 1938 ;Trautwein and Dudel, 1954;Blinks and Koch-Weser, 1963 ;Langer and Brady, 1968;Edman et al, 1974;Mattiazzi and Nilsson, 1976).' Inference of the peak myoplasmic [free Ca 21] from the amplitude of the tension transient at pH 7.25 and 12°C ( Fig.…”

Coupling Langevin Dynamics With Continuum Mechanics: Exposing the Role of Sarcomere Stretch Activation Mechanisms to Cardiac Function

“…Here, SL 0 = 2.1 μm is the unloaded sarcomere length. If we assume the maximal shortening velocity of the cardiac muscle , where ML is the muscle length (Edman et al, 1974 ), the maximal shortening velocity of a half-sarcomere is . However, the previous consideration regarding the fluctuations during the time interval Δ t = 0.25 ns gives the average magnitude of the molecular velocity to be Δ t σ/ t ≈ 0.8 nm/ ns .…”