Microassay of heme oxygenase by high-performance liquid chromatography: application to assay of needle biopsies of human liver.

We developed a microassay for heme oxygenase, in which bilirubin (BR) production was measured by HPLC, and compared it to previously reported spectrophotometric methods. The microassay required as little as 5 mg wet human, rat, or chick embryo liver. Using the HPLC assay, values for heme oxygenase activity in extracts (10,000 g supernatant) of normal human liver obtained by needle biopsies were 44 +/- 7 (pmol BR.min-1.mg protein-1). Spectrophotometric assays of homogenates of human liver resulted in low values for heme oxygenase, due to unknown sources of interference. Comparative values of microsomal heme oxygenase activity were 294 +/- 25, 95 +/- 3, and 87 +/- 9 pmol BR.min-1.mg protein-1 for chick, rat, and human livers, respectively.