Metabolism of thyroid hormones and some derivatives in isolated, perfused rat liver

¹ Sections of Biochemistry and Clinical Pathology, Mayo Clinic and Mayo Foundation, Rochester, Minnesota

The isolated, perfused rat liver has been used to study the metabolic pathways of I¹³¹-labeled l-thyroxine (T4), l-3,5,3'-triiodothyronine (T3), their partially deiodinated derivatives, and d-thyroxine. l-Thyroxine was metabolized less rapidly than the l-thyronines with fewer iodine atoms. l-T4 accumulated in the liver more rapidly than l-3,3',5'T3 or l-3,3'T2 but less rapidly than l-3,5,3'T3 or d-T4. Conjugation with glucuronic acid proceeded in the liver most rapidly from 3,5,3'T3 and at much lower rates from d-T4, l-T4, l-3,3',5'T3, and l-3,3'-diiodothyronine (T2). Deiodination of l-3,3',5'T3 and l-3,3'T2 proceeded most rapidly.

Key Words: l-thyroxine • 3,5,3'-triiodothyronine • 3,3',5'-triiodothyronine • 3,3'-diiodothyronine • d-thyroxine

Submitted on February 1, 1965