Intestinal Transport of Glucuronides and Sulpho-Conjugates

Abstract

Two anion transport systems have been inferred from their selective inhibition by phenoxybenzamine and the differences in the transport rate of various anions in the jejunum and the colon (1). Transport of acidic conjugates of phenolic compounds was now studied in preparations of the isolated mucosa of guinea pig jejunum and colon mounted in flux chambers (2). 1-Naphthol formed a glucuronide and a sulphoconjugate (3), estradiol mainly glucuronides, and p-nitrophenol (PNP) mainly a sulphoconjugate (PNP-S). In jejunal mucosae, with luminal phenol administration glucuronides and sulphoconjugates accumulated in the luminal solution. With phenol administration to the blood side of jejunal mucosae and to the luminal or blood side of colonic mucosae the main part of glucuronides appeared in the blood side solution, whereas sulphoconjugates were released at both faces of the isolated tissue in comparable amounts. — PNP-S was a much better substrate for transepithelial secretion into the luminal solution than p-nitrophenyl glucuronide (PNP-G), when added to the blood side compartment. The sulphonic acid β-naphthol orange inhibited the secretion both of extracellular and intracellular PNP-S.