Beta-blockade and binding of digoxin to skeletal muscle.
The effect of beta-blockade and a 1-h bicycle exercise test on the digoxin concentration in skeletal muscle (thigh) and serum was studied in 10 healthy men, who had ingested 0.5 mg digoxin daily for 2 weeks. Each subject performed two exercise tests at 100-140 W during maintenance digoxin treatment and 24 h after the latest dose. They rested in the supine position for 2.5 h before the exercise. Sixty minutes before the start of the exercise 0.25 mg/kg b.w. propranolol or saline (control) were injected (single-blind). At the end of the exercise the mean heart rate was 30% lower with beta-blockade (P less than 0.001). During exercise the mean skeletal muscle digoxin concentration increased by 29% (P less than 0.01) in the control situation and by 12% (NS) with beta-blockade. The results indicate that propranolol partly inhibits the exercise-induced increase in skeletal muscle digoxin binding. This might be due to inhibition of a catecholamine-induced stimulation of Na+-K+ATPase during exercise.
D000328:Adult; D001665:Binding Sites / Q000187:drug effects; D004077:Digoxin / Q000378:metabolism* / Q000494:pharmacology; D004562:Electrocardiography; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D009132:Muscles / Q000378:metabolism*; D010101:Oxygen Consumption; D005082:Physical Exertion; D011433:Propranolol / Q000494:pharmacology*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D013997:Time Factors
D011943:Receptors, Adrenergic, beta; D004077:Digoxin; D011433:Propranolol