Esterification of injected epicoprostanol in a human subject.

That a necessary requirement for in vivo esterification of 3-hydroxy sterols is the equatorial conformation of the hydroxyl group has been substantiated by the administration of epicoprostanol-3-(3)H (3-OH equatorial) to a man with a complete biliary fistula. Radioactive epicoprostanol was identified in both free and esterified sterols of plasma. The specific activity of biliary sterols was much higher than that of plasma sterols; this indicated a preferential removal of epicoprostanol from circulating sterols. The appearance of tritium in body water demonstrated that a portion of the labeled epicoprostanol underwent oxidation at C-3.