Abstract
Following injection into the upper duodenum of guinea pigs, free C19-steroids were absorbed at the rate of 46% in 10 hr. and C19-steroid conjugates at a rate of 13.1-10.9%. In the walls of the small intestine, free steroids were conjugated with sulfate, yielding steroid sulfates as well as sulfatides. Only a minor portion was conjugated with glucoronic acid or absorbed without undergoing conjugation. During absorption some of the injected steroid sulfates were converted into sulfatides without appreciable hydrolysis. Steroid glucoronides were almost completely hydrolyzed and reconjugated like free steroids. In the liver, free steroids injected into the portal vein were conjugated, predominantly with sulfate. Steroid sulfates passed the liver without hydrolysis, whereas sulfatides underwent hydrolysis and reconjugation. Steroid glucuronides reached the bile unhydrolyzed, but appeared in the peripheral blood only after significant hydrolysis and reconjugation with sulfate.