Effect of deuterium oxide on contraction characteristics and ATPase activity in glycerinated single rabbit skeletal muscle fibers

摘要

We studied the effect of deuterium oxide (1320) on contraction characteristics and ATPase activity of single glycerinated muscle fibers of rabbit psoas. 1320 increased the maximum isometric force P-0 by about 20%, while the force versus stiffness relation did not change appreciably. The maximum shortening velocity under zero load V-max did not change appreciably in D2O, so that the force-velocity (P-V) curve was scaled depending on the value of P-0. The Mg-ATPase activity of the fibers during generation of steady isometric force P-0 was reduced by about 50% in D2O. Based on the Huxley contraction model, these results can be accounted for in terms of D2O-induced changes in the rate constants f(1) and g(1) for making and breaking actin-myosin linkages in the isometric condition, in such a way that f(1)/(f(1) +g(1)) increases by about 20%, while (f(1) +g(1)) remains unchanged. The D2O effect at the molecular level is discussed in connection with biochemical studies on actomyosin ATPase. (C) 2004 Elsevier B.V. All rights reserved.