1. ¹Division of Hypertension, University of Michigan, MI, USA
2. ²Clinical Research Unit, University of Carabobo, Venezuela

Correspondence: Dr MC Delgado, Division of Hypertension, 3918, Taubman Center, Box 0356, University of Michigan, Ann Arbor, MI 48109, USA. E-mail: delgadoc@umich.edu

Received 29 March 2002; Revised 5 November 2002; Accepted 11 November 2002.

Abstract

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 hyper-tensives 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 Ca²⁺ (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.