The force-velocity relation of the rabbit inferior oblique muscle; influence of temperature

Abstract

The contractile properties of the rabbit inferior oblique muscle (IO) were studied in vitro with direct stimulation at temperatures between 20 and 35 degrees C. Isovelocity releases were used to determine the force/velocity relation. Cooling the muscle from 35 degrees C to 20 degrees C increased contraction and half-relaxation times of single twitches with a temperature coefficient (Q10) of 0.4, but did not affect significantly the twitch tension. The tetanic tension increases with increasing temperature (Q10 = 1.32). Cooling decreased the maximum shortening velocity of the IO with a Q10 of 1.6 and the maximum mechanical power with a Q10 of 2.3. At 35 degrees C, the maximum speed of shortening of the muscle (19 +/- 2 muscle lengths/s, mean +/- SEM) corresponded to a maximum shortening velocity of the sarcomeres of 57 +/- 6 microns/s. This value is similar to data obtained for extraocular muscles (EOM) of smaller rodents (mice and rats). In comparison with mammalian limb muscles the isometric and force-velocity properties of mammalian EOM appear to be virtually independent of the size of the animal. Thus, IO is a fast-twitch muscle endowed with a maximum velocity of shortening higher than that of fast-twitch skeletal muscle, but using a tetanic mechanical power lower than that produced by slow-twitch muscle: the combination of these properties makes it ideally suited to move an ocular globe of low mass at high velocity.

Temperature effect on the force/velocity relationship of the fresh and fatigued human adductor pollicis muscle

“…The Q 10 for V max was 1.6 for temperatures between 25.6 and 37.1°C, which is in good agreement with studies of non-human muscle [3,6,22,27]. The most likely explanation for the decrease of V max with muscle cooling is a decreased activity of the actomyosin adenosine triphosphatase (ATPase) [35], which is the most important determinant of shortening velocity [5].…”

Measurement of contractile force of skeletal and extraocular muscles: Effects of blood supply, muscle size and in situ or in vitro preparation

“…In a previous comparison, Frueh and colleagues (2001) found that muscle force (force per cross-sectional area, kN/m 2 ) measured in situ were about six times greater than the highest of those reported previously for extraocular muscles in vitro (Close and Luff, 1974;Asmussen and Gaunitz, 1981;Luff, 1981;Asmussen et al, 1994;Frueh et al, 1994). Our own lab has reported force measurements of the superior oblique muscle obtained in situ to be 3 to 6 times greater than that of the same muscle in vitro (Chen and von Bartheld, 2004;Croes et al, 2007).…”

Thermal effects on the dynamics and motor control of ballistic prey capture in toads: maintaining high performance at low temperature

“…Q 10 >2 (where the temperature coefficient Q 10 is the factor by which a rate increases with a 10°C increase in temperature). This marked decline has been found in a diversity of muscles from a vast array of animals, including vertebrates and invertebrates, endotherms and ectotherms (Putnam and Bennett, 1982;Bennett, 1984;Bennett, 1985;Hirano and Rome, 1984;Renaud and Stevens, 1984;Else and Bennett, 1987;John-Alder et al, 1989;Faulkner et al, 1990;Stevenson and Josephson, 1990;Barnes and Ingalls, 1991;Rome et al, 1992a;Rome et al, 1992b;Swoap et al, 1993;Asmussen et al, 1994;Sobol and Nasledov, 1994;Altringham and Block, 1997;Choi et al, 1998;Donley et al, 2007;Herrel et al, 2007).…”