Reduced Na+,K+-ATPase Activity in Intact Red Cells and Isolated Membranes from Obese Man*

Abstract
Na+,K+-ATPase activity was measured in red blood cells from 20 nondiabetic euthyroid male Pima Indians with varying degrees of obesity; their body mass indices ranged from 22–60 kg/m2. The Na+,K+-ATPase, measured both by 86Rb uptake inintact cells and ATP hydrolysis by purified membranes, was inversely correlated with bodymass index (r = −0.62; P < 0.005 and r = −0.75; P < 0.0001, respectively). These results confirm that obesity is associated with decreased Na+,K+-ATPase in intact red blood cells, and provide the first demonstration of a reduced sodium pump in isolated red cell membrane preparations from obese men.