A radiometric method for the measurement of adenosine 3'-phosphate 5'-phosphosulfate in rat and mouse liver

A rapid, sensitive, and specific procedure for the measurement of adenosine 3'-phosphate 5'-phosphosulfate (PAPS) in rat and mouse liver was developed. The method measures the formation of 1-[1-14C]naphthyl sulfate from 1-[1-14C]naphthol and PAPS (limiting substrate) via a sulfotransferase-catalyzed reaction. Conjugated and unconjugated 1-[1-14C]naphthol are separated by a single chloroform extraction. The method was validated with regard to reaction components, time, tissue preparation technique, and amount of tissue. Further, PAPS, when added to rat and mouse liver (30-120 nmol/g liver) prior to tissue preparation, was quantitatively recovered (87-101%). The assay can detect 150 pmol of PAPS and, consequently, the sensitivity to measure PAPS in mg quantities of liver was obtained. PAPS levels in rat and mouse liver were determined to be 59 +/- 5 and 20 +/- 3 nmol/g liver, respectively. The ease and sensitivity of this method make it suitable for routine use in pharmacologic and toxicologic studies.