Regulation of Digitalis Glycoside Receptors in Digoxin Treatment
In myocardial samples from patients afflicted with heart failure, the Na,K-ATPase occupancy with digoxin as a result of digitalization amounted to 24–34%. Compared with myocardial tissue from human subjects not afflicted with heart failure, there were no indications of cardiac glycoside receptor upregulation in heart failure patients as a result of longterm digoxin treatment. Heart failure reduced myocardial Na,K-ATPase concentration by 26–32%. In skeletal muscles digoxin occupancy was 9–13%. There was no indication of upregulation of skeletal muscle Na,K-ATPase during digitalization. In heart failure patients Na,K-ATPase was downregulated by 25–37%. Following digitalization the femoral venoarterial difference in plasma K increased 50–100% (p < 0.05) during exercise, and decreased 66–75% during recovery. The observations are of patophysiological importance and of importance for the clinical use of digoxin. It is concluded the digoxin should be used in nearly all heart failure patients that can obtain benefit.
Key wordsNa K-ATPase digoxin heart failure potassium
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