The in vivo metabolites of [14C] progesterone in bovine muscle and adipose tissue.

Muscle and adipose tissue were obtained from steers and dairy cows following subcutaneous administration of [14C] progesterone. Following extraction, purification and separation by column, thin layer and gas-liquid chromatography, various radioactive residues from these tissues were identified by their chromatographic mobility, crystallization to constant specific activity and mass spectra. Progesterone constituted 54% of free radioactivity extracted from muscle and 69 and 73% of radioactivity in the free and conjugated portions of extracts, respectively, from fat. Metabolites identified were: 5alpha-pregnane-3,20-dione, 9%, 0%, 0%, 20beta-hydroxy-4-pregnen-3-one, 8%, 11%, 3%; 3alpha-hydroxy-5beta-pregnan-20-one, 13%, 2%, 2%, 3alpha-hydroxy-5alpha-pregnan-20one, 3%, 3%, 6%; 20 alpha-hydroxy-5alpha-pregnan-3-one, 0%, 2%, 3%; of radioactivity in muscle (free) and fat (free and conjugated fractions), respectively. Tentatively identified in fat extracts by chromatographic mobility were: 20alpha-hydroxy-4-pregnen-3-one, 1%, 1% and 3beta-hydroxy-5beta-pregnan-20-one, 0%, 2% of radioactivity in free and conjugated fractions, respectively. The average concentration of steroid in these animals due solely to treatment, calculated from the specific activity of the [14C] progesterone administered, was 3.4 and 18.1 ng/g in muscle and subcutaneous fat, respectively.