EXCRETORY PHYSIOLOGY OF STEROIDAL HORMONES IN LIVER

¹ Departments of Physiology and Pharmacology, School of Medicine, University of New Mexico, Albuquerque, New Mexico

Excretion of steroidal hormones by isolated perfused rat livers was examined with five isotopic steroids: estradiol, progesterone, testosterone, methyltestosterone and cortisone. A single dose of each steroid disappeared rapidly from the perfusion fluid with a half-time of less than two minutes. Excretion into the bile required substantially longer time than disappearance from the perfusion fluid. All of the "steroid" recovered from the bile had been altered from the material which had been injected. Hepatic excretion was also examined during continuous infusion of steroids. Concentrations of isotope in bile were approximately 1000 times greater than in perfusion fluid, attesting to a highly effective concentrating mechanism. Excretion of isotopic steroid metabolites was depressed by probenecid suggesting that steroid metabolites participate in a hepatic transport process for organic anions.