[Effect of heparin on the Mg++-ATPase of the muscle mitochondria of adult and young rabbits].

ATPase activity from freshly prepared, "aged" and "heparin" mitochondria was studied in adult, newborn and 7 day old rabbits. Heparin, incubated with the mitochondria within 2-2.5 hrs at 20 degrees C, increased the activity of endogenous ATPase in the newborn rabbits. Activities of Mg-2++-ATPase and Mg-2+-DNP-ATPase were decreased under effect of heparin in both adult and new born rabbits. In 7 day old rabbits, to the contrary, increased activity of Mg-2+-ATPase and its activation by 2,4-DNP were observed.