Racial differences in intact erythrocyte ion transport

Epidemiologic studies indicate a much higher incidence of hypertension in blacks than in whites, although no clear biochemical correlates to account for such overt racial differences have been identified. In recent years, considerable evidence has linked perturbations in ion transport to the risk of developing hypertension. Potassium (K+) transport and the ouabain-sensitive component of K+ transport in the erythrocyte were measured in 54 healthy, age and sex matched black and white subjects. Blacks have a significantly (p less than 0.001) lower capacity for K+ transport (0.190 +/- 0.03 mumoles K+ per hr per 10(9) red blood cells [RBC] than whites (0.230 +/- 0.03 mumoles K+ per hr 10(9) RBC) with a significantly (p less than 0.001) higher percentage of K+ transport dependent upon ouabain-sensitive mechanisms (blacks 85.26 +/- 4.14 percent versus whites 76.69 +/- 6.67 percent). These data clearly define overt racial differences in K+ transport which suggest that blacks have a more limited capacity to exchange intracellular sodium for extracellular K+, and a higher percentage of that exchange is dependent upon ouabain-sensitive mechanisms. These findings need be kept in mind were clinical studies of ion transport are being assessed and may be germane to the increased prevalence in blacks for the development of hypertension.