The early and late effects of digoxin treatment on the sodium transport, sodium content and Na+K+‐ ATPase or erythrocytes.

Abstract

1 Erythrocyte sodium content, sodium transport (ouabain sensitive sodium flux Eos, and ouabain sensitive efflux rate constant ERCO) sodium, potassium activated ouabain sensitive adenosine triphosphatase (Na+K+ATPase) and plasma digoxin were measured in patients during acute digitalisation and in patients who were on long-term digoxin treatment.2 In the six patients who were studied during digitalisation, the ERCo,, and Na+K+ATPase activity decreased and erythrocyte sodium content increased during days 2-4 of treatment, but there was no change in E0,.3 In 39 patients on long term digoxin therapy (2-119 months) the erythrocyte sodium content was normal, but the erythrocyte Na+K+ATPase activity was higher than the control group. When the results from these 39 patients were divided according to the duration of treatment it was found that the erythrocyte sodium content was higher in patients treated for 2-4 months than in patients treated for longer periods and the erythrocyte Na+K+ATPase activity increased with duration of treatment. In eight patients (duration of treatment >29 months) in whom ERCO and Eo, were measured, ERC.s and Eos were higher than the control group. 4 The results suggest that the effects of digoxin on erythrocytes which occur during acute digoxin treatment do not persist in the long term.5 The possible explanation for the higher ERC0s, Eos and Na+K+ATPase activity in patients treated with digoxin for more than 2 months is discussed.

Effect of AV3V lesions on development of DOCA-salt hypertension and vascular Na+-pump activity.

“…Such an increase in Na + , K + -ATPase activity has been observed in the isolated erythrocytes of patients chronically treated with digoxin. 36 In addition, an increased active transport of sodium and potassium ions has been observed in arterial smooth muscle from DOCA-salt hypertensive rat. 37 38 It has been suggested that these increases in vascular Na + -pump activity result from elevations in the concentration of intracellular sodium associated with increased passive permeability of the cell membrane to this ion.…”

The role of digitalis in the future.

“…Chronic use of cardiac glycosides Both Ford et al (1979) andCumberbatch et al (1981) obtained evidence that cellular changes in erythrocytes associated with digoxin given acutely and including an increase of intracellular sodium concentration were not maintained on chronic treatment. If the effect on the erythrocyte were an indicator of similar changes in the ventricular myocardium then the inotropic effect of digoxin also might not be maintained.…”

Erythrocyte sodium transport and blood pressure in white subjects.

“…Stokes et al 18 found significant correlations between diastolic blood pressure and both 22 Na efflux and 55 Rb influx (a measure of sodium pump activity) for 137 hypertensive and normotensive white males. Rygielski et al 19 reported significant correlations between erythrocyte Naj content and both systolic and diastolic blood pressures as well as between Na,K-ATPase activity and blood pressure for a population of 247 black and white hypertensive and normotensive subjects.…”

“…For example, our studies 21 of the effect of digoxin administration showed that the number of ATPase sites was decreased and Naj was increased but that the sodium efflux per red blood cell remained relatively constant. Others 22 have shown that when digoxin is administered for a longer period, the number of sites and the Naj concentration gradually return to pretreatment values.…”