Na+,K+-ATPase Enzyme Units in Skeletal Muscle and Liver of 14-Day-Old Lean and Obese (ob/ob) Mice

Abstract

SummaryThe number of Na+, K+-ATPase enzyme (EC 3.6.1.3) units in skeletal muscle and liver of 14-day-old lean and obese (ob/ob) mice was assayed from the concentration of high-affinity [3H]ouabain-binding sites in the tissue preparations. The number of [3H]ouabain-binding sites in forelimb and hindlimb muscles of obese mice was 28% lower than in lean littermates. In contrast, livers of lean and obese mice possessed equal numbers of [3H]ouabain-binding sites. The lower number of Na+,K+-ATPase enzyme units observed in skeletal muscle of the 14-day-old obese mice represents one of the earliest reported developmental alterations in an enzyme system in these mice and may be associated with the lower energy expenditure of young obese mice.