Myocardial uptake of digoxin in chronically digitalized dogs.
1 The time course of myocardial uptake of digoxin, increase in contractility and changes in myocardial potassium concentration was studied for 90 min following an intravenous digoxin dose to long-term digitalized dogs. 2 Nineteen dogs were investigated by the use of a biopsy technique which allowed sampling before and after administration of digoxin. 3 Ten minutes after administration of digoxin the myocardial concentration increased from 60 to 306 nmol/kg tissue, the myocardial concentration of digoxin was significantly lower (250 nmol/kg tissue) after 30 min and then increased again. 4 The transmural myocardial distribution of digoxin was uniform before and 90 min after administration of digoxin in long-term digitalized dogs but at 10 min after administration, both the subepicardial and the subendocardial concentration of digoxin were significantly lower than that of the mesocardial layer. 5 During the first 10 min the dp/dtmax increased to 135% of the control level. The increase remained unchanged during the rest of the study. 6 Myocardial potassium decreased throughout the study. 7 The M-configuration of the myocardial uptake curve and the non-uniformity of myocardial distribution of digoxin observed at 10 min after administrating digoxin to long-term digitalized dogs indicate that the distribution of myocardial blood flow may be changed during chronic digitalization.
D000818:Animals; D004077:Digoxin / Q000378:metabolism / Q000494:pharmacology*; D004285:Dogs; D006321:Heart / Q000187:drug effects*; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D013268:Stimulation, Chemical; D013997:Time Factors
D004077:Digoxin; D011188:Potassium