Arguments for the presence of a Na-K ATPase pump inhibitor in the plasma of uremic and essential hypertensive patients.

The effect of salt and/or volume depletion has been tested in 6 end-stage renal disease and 11 essential hypertensive patients (HTA) on red blood cell (RBC) ionic fluxes. Volume depletion promotes an increase in the RBC Na-K ATPase activity with, as a result, a significant decrease in intracellular sodium concentration [Na)ic). Moreover, a factor has been found in the plasma of uremic subjects which causes natriuresis when injected in rat renal arteries. The concentration of this factor decreases during dialysis in relation to the weight loss and the increase in the RBC Na-K pump activity. In essential hypertension, the effect of a low salt diet on the blood pressure is correlated with the improvement of RBC Na-K ATPase activity. These experiments illustrate the presence of a Na-K ATPase inhibitor in the plasma of these subjects, dependent on sodium and water balance.