Ventromedial Hypothalamic Lesions Reduce the Number of Na +,K + -ATPase Enzyme Units in Skeletal Muscle of Weanling Rats 1

Abstract

Weanling rats with ventromedial hypothalamic (VMH) lesions retained 66% more body energy 1 to 4 weeks postsurgery than did nonlesioned control rats. The increased energy retention in VMH-lesioned rats resulted from diminished energy expenditure rather than from elevated energy intake. Numbers of Na⁺, K⁺-ATPase enzyme units in skeletal muscle and kidneys of these rats were estimated from saturable [³H]ouabain binding to particulate fractions. Skeletal muscle of VMH-lesioned rats had 36% fewer Na⁺, K⁺-ATPase enzyme units than did skeletal muscle of control rats. VMH-lesions did not affect the number of Na⁺, K⁺-ATPase enzyme units in kidneys. These results are comparable to earlier reports on Na⁺, K⁺-ATPase enzyme units in muscle and kidneys of obese (ob/ob) mice and suggest that there is an association between development of obesity and reduced number of Na⁺, K⁺-ATPase enzyme units in skeletal muscle.