372 INFLUENCE OF FRUCTOSE-1,6-DIPHOSPHATE ON 22NA UPTAKE OF RED BLOOD CELLS FROM NORMOTENSIVE AND HYPERTENSIVE BLACK AND WHITE PERSONS

Uptake of 22 Na+ by red blood cells (RBC) in low Na+ and high K+ medium is more rapid in cells from hypertensive (HT) than normotensive (NT). Since the energy in RBC for ionic transport is derived from glycolysis and fructose-1,6-diphosphate (FDP) increases in vitro and in vivo RBC ATP content, we assessed whether FDP will influence the uptake of 22 Na+ in RBC from NT and HT blacks and whites by employing the method of Eaton and Mahoney. Hypertensives had significantly higher flux than normotensives of the same race, but blacks had significantly lower fluxes than whites. The decrease in uptake after FDP was not due to pH, as buffering the medium did not change the FDP effect, and pH change alone did not change uptake, nor to increased osmolality, as mannitol did not change uptake. (table) We conclude that the elevated 22 Na uptake of RBC from white HT is normalized by FDP and that the uptake by cells from blacks is closer to that from whites after FDP. The results raise the possibility that the high 22 Na uptake of HT corrected by FDP represents defective function of glycolysis.