Temperature dependence of the inhibitory effects of orthovanadate on shortening velocity in fast skeletal muscle

Biophys J. 1994 May;66(5):1554-62. doi: 10.1016/S0006-3495(94)80947-6.

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Actins / chemistry
  • Actins / physiology
  • Animals
  • Biomechanical Phenomena
  • Biophysical Phenomena
  • Biophysics
  • Hot Temperature
  • In Vitro Techniques
  • Isotonic Contraction / drug effects
  • Isotonic Contraction / physiology
  • Kinetics
  • Molecular Structure
  • Muscle Contraction / drug effects*
  • Muscle Contraction / physiology
  • Myosins / chemistry
  • Myosins / physiology
  • Rabbits
  • Temperature
  • Vanadates / pharmacology*

Substances

  • Actins
  • Vanadates
  • Myosins