Reduced Na+, K+ -ATPase activity in intact red cells and isolated membranes from obese man.

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 in intact cells and ATP hydrolysis by purified membranes, was inversely correlated with body mass index (r = -0.62; P less than 0.005 and r = -0.75; P less than 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.