Reduced Activity of the Red-Cell Sodium-Potassium Pump in Human Obesity

Abstract

Looking for evidence of reduced energy use in the cells of obese persons, we measured the numbers of sodium-potassium-pump units in erythrocytes from a group of 21 obese human subjects and found them to be reduced by 22 per cent as compared with those of nonobese controls (P<0.001). The cation-transport activity of the pump, as measured by 86rubidium uptake by the cells, was also reduced in parallel with the decrease in pump units. An increased concentration of sodium in the red cells of obese subjects was also found (9.6±0.7 vs. 7.1 ±0.6 mmol per liter of cells; P<0.01). This finding demonstrates independently the physiologic importance of reduced numbers of sodium-pump units and reduced pump activity as measured by ouabain binding and rubidium transport, respectively.