INFLUENCE OF DIURETICS ON ELECTROLYTE AND WATER CONTENT OF HUMAN ERYTHROCYTES

The influence of diuretic agents on intracellular sodium and potassium concentrations has been studied in human erythrocytes. The erythrocytes were incubated with 4 diuretic compounds: Mersalyl (50, 80, 170, 340, 500 mg/l) Hydrochloro-, thiazide, Furosemide and Ethacrynic acid (each compound in concentrations of 250, 500 und 1,000 mg/l) either at 4°C for 48 hrs. or previously for 72 hrs. at 4°C incubated erythrocytes were reincubated with glucose added at 37°C for 3 hrs. The alterations in intracellular Na/K ratios were compared to those obtained with similar treated cells but without the diuretic added. With Mersalyl, Hydrochlorothiazide, and Ethacrynic acid an increase in Na/K ratio as compared to the control ratio was obtained during 48 hrs. incubation at 4°C. This effect could be reversed by adding cystein chloride in twice the molar concentration to Mersalyl treated erythrocytes, whereas the addition of cystein to the Hydrochlorothiazide and Ethacrynic acid treated cells resulted in prompt hemolysis. The effect of Mersalyl, Hydrochlorothiazide and Ethacrynic acid treated cells during incubation at 4°C suggests an effect on membrane permeability both to Na and K ions. Of all the diuretics studied only Ethacrynic acid showed an effect on the Na/K ratio during incubation at 37°C as compared to the control values, thus suggesting an additional effect of this compound on active cation transport. Furosemide had no effect in all concentration-ranges neither at 4°C nor at 37°C. This lacking effect of Furosemide might be due to the poor lipid solubility of the diuretic. It has to be emphazised however that the observed effects of diuretic agents on cation transport in erythrocytes cannot easily be compared to the effect of the various compounds on the renal tubule considering the differences in energy-metabolism, net-cation-fluxes and the uncertainty of intracellular accumulation of the diuretic agents within the erythrocytes. © 1968 Springer-Verlag.