Role of the lymphatic system in the transport of absorbed 7,12-dimethylbenzanthracene in the rat.

To determine the role of the intestinal lymphatic system in the absorption of a polycyclic aromatic hydrocarbon, 7,12-dimethylbenzanthracene, a radiolabeled preparation of the compound was given by intraduodenal infusion to rats in doses of 10 micrograms, 10 mg and 20 mg in olive oil solution. The hydrocarbon appeared to be absorbed from the intestine in a fractional manner, ca. 20% of the administered radioactivity being recovered totally in bile and intestinal lymph in 24 hr at all three dose levels. Biliary radiolabel accounted for 75-82% of combined recovery of radioactivity in bile and lymph with all three doses. The recovery of significant amounts of radiolabel in bile before the appearance of isotope in lymph, together with the fact that the biliary radiolabel greatly exceeded at all times the lymphatic recovery of isotope, suggests that an alternative pathway, presumably the portal venous route, is of major importance in the transport of the absorbed hydrocarbon.