| Abstract: | ![]()
The effect of endotoxin administration on the integrity of sodium pump was studied in canine heart myocardium. Sodium pump activity was determined based on the 86Rb+ uptake by ventricular muscle strips. The results show that 4 hr following endotoxin administration the ouabain-sensitive 86Rb+ uptake was inhibited by 44-70%, and the inhibition was noncompetitive with 86Rb+ ions and was independent of Na+ concentrations. The sensitivity of sodium pump toward verapamil inhibition was unaffected by endotoxin administration, suggesting that the endotoxin-induced decrease in sodium pump activity is not mediated through alteration in either calcium or slow sodium channel. The sensitivity of 86Rb+ uptake to ouabain inhibition was decreased approximately sixfold in endotoxin-injected dogs. These data suggest that sodium pump is greatly impaired in dog hearts 4 hr after endotoxin administration. The impairment in sodium pump might have physiological significance in the development of myocardial dysfunction during endotoxic shock. |
