Influence of race, sex, and blood pressure on erythrocyte sodium transport in humans.

Sodium transport of erythrocytes from normotensive and essential hypertensive subjects was evaluated by determining ouabain-sensitive and ouabain-insensitive sodium efflux rates, Na+-Li+ countertransport rates, Li+-K+ cotransport rate constants (lithium replacing sodium), intracellular sodium concentrations, and the number of Na+,K+-adenosine triphosphatase (ATPase) sites per erythrocyte. Subjects included men and women, blacks and whites. Hypertensive subjects had significantly higher sodium transport than did normotensive subjects for ouabain-sensitive sodium efflux (p less than 0.025) and Na+-Li+ countertransport (p less than 0.001). Sexual differences were noted for ouabain-sensitive (p less than 0.001) and ouabain-insensitive (p less than 0.001) sodium efflux, for intracellular sodium concentration (p less than 0.025), and for the Li+-K+ cotransport rate constant (p less than 0.005), all with higher values for men than for women. Racial differences were noted for ouabain-insensitive sodium efflux (p less than 0.005), Na+-Li+ countertransport (p less than 0.001), and the Li+-K+ cotransport rate constant (p less than 0.001); values were higher in whites than blacks for all three measurements. The number of [3H]ouabain binding sites was lower for blacks (p less than 0.001) and the intracellular sodium concentration was higher for blacks (p less than 0.001). Among all subjects, significant (p less than 0.001) correlations were found between intracellular sodium concentration and the number of Na+,K+-ATPase sites per erythrocyte (r = -0.78) and between the ouabain-sensitive sodium efflux per site and intracellular sodium concentration (r = 0.85, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)