DIURNAL-VARIATION OF ERYTHROCYTE SODIUM LITHIUM COUNTERTRANSPORT RATE AND INTRACELLULAR CATION CONCENTRATIONS

Differences in erythrocyte sodium-lithium countertransport rate and erythrocyte potassium concentration were found between 0900 h and 2100 h in ten healthy individuals. Sodium-lithium countertransport rates were lowest at 0900 h (x: 0.34 mmol/l per h; SD: 0.15) and highest at 1200 h (x: 0.42 mmol/l per h; SD: 0.16). Erythrocyte potassium concentrations increased progressively during the day, while erythrocyte sodium concentrations did not change significantly during the day. For comparative and epidemological studies of erythrocyte sodium-lithium counter-transport rate blood samples should be taken at the same time of the day. © 1990.