Effect of Deuterium Oxide on the Relaxation of Glycerol-extracted Muscle

Abstract

DEUTERIUM oxide is known to retard the contraction of living muscle^1–3. The site of its action, however, remains obscure; it affects significantly neither the membrane excitation^4–6 nor the contraction of the proteins in glycerol-extracted muscle⁵. Deuterium oxide has, however, a differential effect on the contractile response to a number of nucleotides; whereas the interactions with adenosine triphosphate (ATP) and cytodine triphosphate (CTP) are not affected, those with inosine triphosphate (ITP) and uridine triposphate (UTP) are retarded⁵. The ATPase of myofibrils⁶ and myosin B⁷ is reduced by deuterium oxide under certain conditions; at neutral pH the myosin B ATPase is, however, not significantly affected⁷. In the case of ITPase, the reaction is always slower on substitution of deuterium oxide for normal water (H₂O) (ref. 7).