title: Temperature sensitivity of force and shortening velocity in maximally activated skinned smooth muscle.
abstract: We have studied the temperature dependence of isometric force, rate of force development and maximal shortening velocity (Vmax) in skinned guinea-pig taenia coli smooth muscle. To eliminate the influence of temperature on activation mechanisms, maximally thiophosphorylated preparations were used. Isometric force in the range 2-35 degrees C was maximal at 22 degrees C with a decrease of 25% at 2 degrees C and 10% at 35 degrees C. Rate of tension development from rigor after photolytic release of ATP increased four-fold between 5 degrees C and 30 degrees C. Vmax increased with a Q10 of about 2 (1.6, range 5-15 degrees C, and 2.2, range 22-30 degrees C). The temperature dependence of the rate of tension development indicates rate-limitation by transitions into force-generating states or by the hydrolysis reaction. The temperature dependence of Vmax reflects effects of temperature on reactions (e.g. the ADP-release) associated with cross-bridge detachment. The small temperature dependence of steady-state force in smooth compared with skeletal muscle suggests differences in the cross-bridge reactions controlling the number of attached force-generating states in the two muscle types.
authors.affiliation: Department of Physiology and Neuroscience, Lund University, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Jaworowski
authors.forename: A
authors.initials: A
authors.lastname: Arner
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D003106:Colon / Q000502:physiology*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000502:physiology*; D007700:Kinetics; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D009130:Muscle, Smooth / Q000502:physiology*; D010782:Photolysis; D011930:Reaction Time; D013314:Stress, Mechanical; D013696:Temperature
chemical_list: C022571:adenosine 5'-O-(3-thiotriphosphate); D000255:Adenosine Triphosphate