EFFECT OF THYROXINE ON OXYGEN CONSUMPTION AND HEART RATE FOLLOWING BILE DUCT LIGATION AND PARTIAL HEPATECTOMY

Abstract

TO study the influence of the liver on the biological action of thyroxin, the response of the oxygen consumption and heart rate of the rat to a 1-mg. dose was examined after bile duct ligation, partial hepatectomy, or both. The rate of oxygen consumption was estimated by direct measurement of the oxygen uptake, and the heart rate was detd. with the help of the ecg. In a preliminary expt., thyroxin proved more effective when given subcut. than intraperit., a result implicating the liver, since a substance comes into more immediate contact with the liver when absorbed by the peritoneal than when absorbed by the subcut. route. Thyroxin is more effective after bile duct ligation, presumably because this operation prevents the biliary excretion of thyroxin and causes its retention in the body. Further increase in thyroxin activity may be produced if a partial hepatectomy is also performed, presumably because this operation removes tissue that normally would have transformed thyroxin into substances with little or no biological action. These results indicate that the liver excretes and inactivates excess amts. of thyroid hormone.