Potassium removal as a factor limiting the correction of acidosis during dialysis

The diffusional fluxes of urea, potassium and bicarbonate across the dialysis membrane (external balance) were determined in seven patients during haemodialysis using potassium free dialysate and dialysate containing 2.0mEq/L of potassium. The results show an inverse correlation between extraction of potassium and intake of bicarbonate in both external and internal balances. This is probably due to the increase in cell membrane electrical potential resulting from a fall in blood potassium and emphasises the importance of electrical driving forces in diffusional fluxes across cellular membranes.