Characteristics of active sodium and potassium transport in erythrocytes in children with different stages of symptomatic uremia.

Abstract

Erythrocytes from 15 uremic children aged from 7 months to 16 years were analyzed for adenosine triphosphatase (total ATPase and ouabain sensitive ATPase i.e. Na+, K+-ATPase), sodium and potassium ions and ATP concentration, in some cases before and after therapeutic measures had been undertaken. No correlation was found between the levels of Na+, K+-ATPase and serum creatinine and all uremic children had Na+, K+-ATPase levels within the range for normal children. The children with rapidly progressive uremia had higher activities of Na+, K+-ATPase at the corresponding serum creatinine concentration than those with slowly progressive uremia. Longitudinally the Na+, K+-ATPase activities fell and the erythrocyte Na+-K+ ratio increased in slowly progressive uremia. Introduction of a low-protein, high-energy diet giving accelerated growth did not change the Na+, K+-ATPase activities, the concentrations of erythrocyte sodium and potassium ions or ATP. Hemodialysis gave a slight increase of Na+, K+-ATPase and of the erythrocyte Na+-K+ ratio, whereas renal transplantation resulted in a remarkable increase of Na+, K+-ATPase activity and decrease of Na+-K+ ratio. A distinct feature of uremic children with hypertension was a low erythrocyte Na+-K+ ratio and a high Na+, K+-ATPase level.