6,7-(3)H-Estriol-16alpha-glucosiduronate-(14)C was administered to eight women (nine studies) by several routes: both injection and infusion (300 min) into the cubital vein, injection into the portal vein system, ingestion and instillation into the duodenum, jejunum, and ileum. Urine, collected from 0-2, 2-4, 4-8, 8-12, and 12-24 hr, was analyzed by countercurrent distribution for its content of radioactive 3- and 16-glucosiduronate (E(3)-3Gl,E(3)-16Gl) and sulfoglucosiduronate (E(3)-3S,16Gl) of estriol as well as for (3)H/(14)C ratio of each conjugate. After peripheral injection 50-60% of the injected E(3)-16Gl was excreted unchanged along with about 5% as E(3)-3S,16Gl with an unchanged (3)H/(14)C ratio, indicating direct sulfation of the injected E(3)-16Gl. During a 300 min infusion, urinary excretion closely resembled that following injection. But 2-4 hr after the end of the infusion excretion of E(3)-3S, 16Gl stopped, excretion of E(3)-3Gl (17%/24 hr) with an elevated (3)H/(14)C ratio started, and excretion of E(3)-16Gl continued (70%/24 hr), but with a rapidly increasing (3)H/(14)C ratio. This indicated sequestration in a sluggishly metabolizing compartment where two processes occurred: (a) extensive hydrolysis of E(3)-16Gl followed by reconjugation at either C3 or C16 with unlabeled uridine diphosphate glucuronic acid (UDPGA), thereby increasing the (3)H/(14)C ratio; and (b) transconjugation from C16 to C3, thereby producing E(3)-3Gl with finite (3)H/(14)C ratios. Instillation into various segments of the small intestine produced results qualitatively similar to those after intravenous infusion, whereas ingestion and intraportal injection resembled peripheral intravenous injection. Therefore, we have postulated the possibility of an enteric circulation (in addition to an enterohepatic circulation) in which the steroid or its conjugates are transported into the small intestine in the succus entericus, modified, and then reabsorbed and excreted in the urine-a process which requires several hours.

Adolescent↗

PubMed1969

Studies on phenolic steroids in human subjects. IX. Role of the intestine in the conjugation of estriol.

In order to compare the enteric circulation of estriol-16alpha-glucosiduronate (see preceding paper) with that of estriol (E(3)), labeled estriol was administered to six women by several routes: both injection and infusion (300 min) into the cubital vein, injection into the portal vein system, ingestion and instillation into the jejunum and ileum. Urine, collected from 0-2, 2-4, 4-8, 8-12, and 12-24 hr, was analyzed by countercurrent distribution for its content of radioactive 3- and 16-glucosiduronate (E(3)-3Gl,E(3)-16Gl) and sulfoglucosiduronate (E(3)-3S,16Gl) of estriol. After peripheral injection of E(3), E(3)-16Gl was excreted rapidly and E(3)-3S,16Gl at a slower and more constant rate. E(3)-3Gl was barely detectable after infusion. After injection of E(3) into the portal vein, the excretion of E(3)-3S,16Gl was greater and quicker than after peripheral injection. Even in a subject with a complete bile fistula, the urinary excretion of E(3)-3S,16Gl was essentially unchanged. Ingestion also produced the same result. Only after instillation into the ileum was a large and rapid excretion of E(3)-3Gl obtained, whereas the excretion of E(3)-3S,16Gl, and E(3)-16Gl were depressed. These results together with those of the preceding paper suggest that E(3) does not readily appear in the small intestine except via a hepatoenteric circulation that produces very little E(3)-3Gl. When present in the distal segment of the small intestine, however, absorption, conjugation, and elimination proceed readily.

Biliary Fistula↗

PubMed1968