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Research Article Free access | 10.1172/JCI105831
1Endocrine Research Laboratory, Medical Division, Montefiore Hospital and Medical Center, and the Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10467
Find articles by Oppenheimer, J. in: JCI | PubMed | Google Scholar
1Endocrine Research Laboratory, Medical Division, Montefiore Hospital and Medical Center, and the Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10467
Find articles by Bernstein, G. in: JCI | PubMed | Google Scholar
1Endocrine Research Laboratory, Medical Division, Montefiore Hospital and Medical Center, and the Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10467
Find articles by Surks, M. in: JCI | PubMed | Google Scholar
Published June 1, 1968 - More info
Administration of phenobarbital to rats in a dosage schedule previously demonstrated to increase hepatocellular binding of thyroxine results in increased hormonal turnover, due both to increased deiodination and to fecal disposition of thyroxine iodine. The rate of biliary excretion of thyroxine iodine is roughly proportional to the hepatic content of exchangeable thyroxine. The enhanced peripheral disposition of thyroxine appears to lead to increased thyroidal function, as measured by isotopic iodine studies, and the maintenance of a normal nonradioactive serum PBI. On the other hand, thyroidectomized animals maintained on a constant replacement dose of L-thyroxine and treated with phenobarbital exhibit a marked fall in serum PBI. These findings suggest that increased thyroxine flux in phenobarbital-treated animals is secondary to primary stimulation of hepatocellular binding. Exchangeable intracellular thyroxine may thus be an important determinant of hormone turnover and, possibly, of hormonal action.