Intracellular sodium and potassium concentrations in erythrocytes of patients with primary aldosteronism.

Intracellular concentration of sodium ([Na]i) and potassium ([K]i), and the ouabain sensitive sodium efflux rate constant (ERCos) in erythrocytes were determined in patients with primary aldosteronism, before and after the surgical removal of the adrenocortical adenoma and in comparison to those in healthy controls. Without treatment, [Na]i was higher and ERCos was lower in patients with primary aldosteronism than in controls (10.60 +/- 0.96 vs. 8.25 +/- 0.89 mmol/l cells, p less than 0.01; 0.156 +/- 0.040 vs. 0.255 +/- 0.047/hour, p less than 0.01, respectively). After the surgery, [Na]i was decreased to 7.70 +/- 0.64 mmol/l cells and ERCos was increased to 0.273 +/- 0.031/hour and these values were similar to those in controls. [K]i in primary aldosteronism was not affected by the surgery (from 96.79 +/- 2.03 to 98.8 +/- 3.84 mmol/l cells) and was not different from that in controls (99.11 +/- 3.42 mmol/l cells). In 2 patients, normalization of the serum potassium following an oral potassium chloride supplement caused only partial improvement in [Na]i and ERCos. These results suggest that an inhibition of sodium pump activity resulting in elevated [Na]i may play an important role in the pathogenesis of high blood pressure in patients with primary aldosteronism.