Metabolism of 3,3'-Diiodothyronine and 3'-monoiodothyronine, and effect of potassium cyanide and dinitrophenol and glucuronidation of thyroxine in cultured rat hepatoma cells.

Rat hepatoma cells (R117-21B) metabolized 3,3'diiodothyronine and 3'-monoiodothyronine by sulfation and glucuronidation. Glucuronidation of iodothyronines (a mixture of 3,3'-diiodothyronine, approximately 99%, and 3'-monoiodothyronine, approximately 10%(was very rapid and 83% of the total 125I in the medium was their glucuronides after 8 hr incubation with the cells at 37 degrees C. Iodothyronine sulfates (approximately 9% of the total 125I) were also detected. No clear increase in free iodide was observed during the 8 hr incubation. The effect of KCN or dinitrophenol on glucuronidation of thyroxine was investigated. Both drugs inhibited glucuronidation, and dinitrophenol was more effective than KCN. Dinitrophenol accelerated the liberation of 125I- in the metabolism of thyroxine in the cultured rat hepatoma cells.