The Na+-K+-pump, energy metabolism, and obesity

In intact soleus and extensor digitorum longus muscles obtained from lean and obese mice, the number of [³H]-ouabain binding sites showed no significant difference. In the same muscles obtained from obese mice, the Na⁺-K⁺-pump mediated [⁴²K]-uptake was respectively 39 and 33% larger than in those of lean littermates. This together with the earlier observation that intact muscles require at most 6% of their basal energy production for active Na⁺-K⁺-transport indicates that this process is of no quantitative importance for development of obesity.