The Effect of Hypokalaemia and of Digoxin Therapy on Red Cell Sodium and Potassium Content. Some Clinical Aspects

Abstract

Red cells from patients with hypokalaemia were found to have gained sodium and lost potassium. Below a threshold of about 3.5-3.75 mmol potassium/l plasma, an increase in red cell sodium developed quite sharply, and an inverse relation to the red cell sodium concentration was clearly present. The onset of this relation was defined as the threshold of hypokalaemia and identified as the minimum concentration of potassium in plasma required to cause a measurable increase in red cell sodium. So determined, the limit for hypokalaemia agreed well with the generally accepted lower limit for plasma potassium derived statistically. The effect of digoxin treatment was also studied, and in 21 patients, after 10 days of treatment, an increase in red cell sodium concentration from 7.1 ± 1.5 to 11.9 ± 3.8 mmol/1 red cells and a decrease in red cell potassium concentration from 99.6 ± 3.7 to 95.3 ± 4. 9 mmol/l red cells were found. It is consistent with the hypokalaemia - digitalis glycoside interaction that this effect of digoxin treatment was found to be identical to that of hypokalaemia.

Key Words:

• Active biological transport
• alkalosis
• cell membrane permeability
• digitalis glycosides
• digoxin
• erythrocytes
• hypokalaemia
• mineralocorticoids
• potassium
• sodium
• steroids