[Mg 2+, Ca 2+-ATPase of skeletal muscle nuclei in normal rabbits and in rabbits with experimental muscular dystrophy]

Abstract

The total ATPase activity of the rabbit skeletal muscle nuclei was established to be a sum of activities of two ATPases--Mg2+ and Mg2+, Ca2+-ATPases. The latter composes 50% of total ATPase activity for skeletal muscles nuclei of the normal rabbits and 30% for skeletal muscles nuclei of the rabbits with muscular dystrophy. Mg+, Ca2+-ATPase of the skeletal muscle nuclei is activated by calcium ions within a range of 10(-6)--10(-4) M and is inhibited with its concentration of 0.5-10(-3) M and higher. Sodium and potassium ions activate Mg2+, Ca2+-ATPase. Inhibition of Mg2+-ATPase is observed for the skeletal muscle nuclei of the rabbits in norm with the presence of 80 mM of Na+ and 70 mM of K+ in the incubation medium. Under experimental muscular dystrophy such an effect is not observed in connection with the fact that the concentration of monovalent cations in the incubation medium does not exceed 60 mM. The ATPase activity in nuclei of the rabbit skeletal muscles may be also manifested in the presence of Mn2+ greater than Ca2+ greater than Ba2+. A problem is under discussion as to substitution of ions Mg2+ by ions Mn2+, Ca2+, Ba2+ in manifestation of the Mg2+ATPase activity for the skeletal muscle nuclei of the normal rabbits and of those with experimental dystrophy.