ATP Depletion in Thyrotoxic Rats

Effect of endotoxin from E. coli on the ATP content in heart muscle, the liver and the kidney of thyrotoxic rats was studied. When endotoxin (200-400 ƒÊ g) was intravenously injected to rats taking drinking water containing 2-7.5 ƒÊ g T3 per ml, body temperature rose and the heart rate increased. At the same time, a marked decrease in the ATP content in heart muscle and the kidney was observed together with an increase in Na+-K+-ATPase activity. Such changes were not observed or seen only to a small extent in euthyroid rats after endotoxin administration. Endotoxin-induced ATP depletion in T3treated rats was prevented by administration of 5 mg hydrocortisone just prior to endotoxin injection. These findings indicate that endotoxin easily causes ATP depletion in some tissue or organs in thyrotoxicosis, even if the dose of endotoxin is not enough to produce such an effect in the euthyroid. These observations are of interest in relation to thyroid storm associated with bacterial