Abstract
Summary
The incorporation of glycine-U-C14, glutamic acid-U-C14, glutamine-U-C14, cystine-S35 and glutathione-S35 into the major mercaptide conjugate of sulfobromophthalein (BSP) was studied in bile from isolated perfused rat liver. Incorporation of label from each of the amino acids was demonstrable in the purified metabolite obtained after 3 serial chromatographic steps, whereas control fractions were negative. Acid hydrolysis of the metabolite and subsequent paper chromatography revealed that the amino acids had been incorporated intact, that 3 M of amino nitrogen were released for each M of BSP, and that glycine and glutamic acid were in equimolar ratio (cysteine was degraded during hydrolysis and could not be quantitatively recovered). High concentrations of cysteine in the perfusate did not compete with glutathione for the synthesis of BSP mercaptide. It was concluded that BSP is secreted into bile, at least in part, as a mercaptide conjugate with glutathione.
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