1-Naphthol metabolism and metabolite transport in the small and large intestine. II: Effect of sulphate and phosphate ion omission, and of 2,6-dichloro-4-nitrophenol in the isolated guinea pig mucosa.

A previous study (Sund & Lauterbach 1986) in the isolated guinea pig mucosa showed a complex pattern of 1-naphthol (I) metabolism and metabolite (glucuronide = II and sulphate = III) transport in relation to tissue studied (jejunum and colon) and administration side (lumen versus blood side). In the present paper aspects of I metabolism and II and III transport have been further studied. The experiments involved: Omission of inorganic sulphate in the incubation solution at one particular side or at both sides, to see if and how intestinal sulphoconjugation depended on side of sulphate ion entry, and if II and III efflux might be linked to sulphate ion influx. Similar omission experiments with inorganic phosphate, and Incubation in presence of 2,6-dichloro-4-nitrophenol (IV), a drug claimed to be a selective inhibitor of sulphoconjugation. The experiments showed: In the jejunum, sulphate ion caused a much stronger stimulation of III formation from the lumen than from the blood side, when I was added at the luminal side. In the colon, however, the sulphate ion was more effective on the blood side than on the lumen side, regardless of side at which I was added. More experiments are needed to clarify if conjugate efflux is affected by sulphate ion omission as well. Omission of inorganic phosphate did neither affect I metabolism nor II and III efflux. IV (present at both sides at once) had complex effects, involving inhibition of II and III synthesis as well as their efflux, and, in part, a change in their normal lumen: blood distribution pattern.(ABSTRACT TRUNCATED AT 250 WORDS)