Red blood cell K+ could be a marker of K+ changes in other cells involved in blood pressure regulation.

The aim of this study is to determine whether red blood cell K(+) content (RBC(Ki)) is associated with blood pressure levels and, if so, could RBC(Ki) be a marker of potassium changes in other cells involved in blood pressure regulation. The study was performed on 50 untreated hypertensives, 32 of their offspring and 50 age- and sex-matched controls. Systolic (SBP) and diastolic (DBP) blood pressures, height, weight, plasma, urine and red blood cell electrolytes were measured in all subjects. RBC(Ki) was significantly lower in hypertensives than in offspring of hypertensives and normotensive controls. Offspring of hypertensives had significantly lower RBC(Ki) than normotensive controls. Plasma K(+) was significantly lower both in hypertensives and offspring of hypertensives when compared to normotensive controls. A significant negative correlation was found in hypertensives between RBC(Ki) and DBP (r=-0.27, P=0.04) and in offspring of hypertensives between RBC(Ki) and DBP (r=-0.43, P=0.02). A significant correlation was found in hypertensives between RBC(Ki) and plasma K(+) (r=0.3, P=0.02). A positive correlation with borderline significance was found in hypertensives between RBC(Ki) and ionized Ca(2+) (r=0.2, P=0.1). In conclusion, our results support the hypothesis that RBC(Ki) is associated with blood pressure levels and that the measurement of RBC(Ki) levels may represent a biochemical marker for K(+) changes in other cells involved in blood pressure regulation. Further studies are necessary to explain the exact mechanisms of reduced RBC(Ki) levels in hypertensive patients and their offspring.