Increased leucocyte Na-K ATPase in obesity: reversal following weight loss

Ouabain-sensitive 86Rb influx and [3H] ouabain binding capacity were investigated in the leucocytes of 17 obese patients and 15 control subjects. Both were significantly increased in the obese when compared with controls. Following dietary restriction and a 4% to 5% weight reduction in the obese over 2 weeks, [3H] ouabain binding and ouabain-sensitive 86Rb influx (a model for K+ influx) decreased to levels similar to those in controls. This shows that the number of Na-K ATPase sites on leucocyte membranes of the obese are significantly increased and that this is associated with accelerated 86Rb transport. Since both of these indices decreased following 4% to 5% reduction in body weight while the patients were still obese, increased Na-K ATPase is neither a marker of nor cardinal to the pathogenesis of obesity. We conclude that (1) increase in Na-K ATPase units and 86Rb influx are not characteristic of obesity itself and (2) dietary restriction over the short-term with limited weight reduction restores Na-K ATPase units and 86Rb influx to normal.