title: Temperature dependence of the inhibitory effects of orthovanadate on shortening velocity in fast skeletal muscle.
abstract: We have investigated the effects of the orthophosphate (P(i)) analog orthovanadate (Vi) on maximum shortening velocity (Vmax) in activated, chemically skinned, vertebrate skeletal muscle fibers. Using new "temperature-jump" protocols, reproducible data can be obtained from activated fibers at high temperatures, and we have examined the effect of increased [Vi] on Vmax for temperatures in the range 5-30 degrees C. We find that for temperatures < or = 20 degrees C, increasing [Vi] inhibits Vmax; for temperatures > or = 25 degrees C, increasing [Vi] does not inhibit Vmax. Attached cross-bridges bound to Vi are thought to be an analog of the weakly bound actin-myosin.ADP-P(i) state. The data suggest that the weakly bound Vi state can inhibit velocity at low temperature, but not at high temperature, with the transition occurring over a narrow temperature range of < 5 degrees C. This suggests a highly cooperative interaction. The data also define a Q10 for Vmax of 2.1 for chemically skinned rabbit psoas fibers over the temperature range of 5-30 degrees C.
authors.affiliation: Department of Pure and Applied Mathematics, Washington State University, Pullman 99164.
authors.forename: E
authors.initials: E
authors.lastname: Pate
authors.forename: G J
authors.initials: GJ
authors.lastname: Wilson
authors.forename: M
authors.initials: M
authors.lastname: Bhimani
authors.forename: R
authors.initials: R
authors.lastname: Cooke
mesh_terms: D000199:Actins / Q000737:chemistry / Q000502:physiology; D000818:Animals; D001696:Biomechanical Phenomena; D055592:Biophysical Phenomena; D001703:Biophysics; D006358:Hot Temperature; D066298:In Vitro Techniques; D007551:Isotonic Contraction / Q000187:drug effects / Q000502:physiology; D007700:Kinetics; D015394:Molecular Structure; D009119:Muscle Contraction / Q000187:drug effects* / Q000502:physiology; D009218:Myosins / Q000737:chemistry / Q000502:physiology; D011817:Rabbits; D013696:Temperature; D014638:Vanadates / Q000494:pharmacology*
chemical_list: D000199:Actins; D014638:Vanadates; D009218:Myosins