UNIT 4.32 In Vitro Assays of Inorganic Arsenic Methylation

  1. Zuzana Drobna1,
  2. Miroslav Styblo1,2,
  3. David J. Thomas3

Published Online: 1 NOV 2009

DOI: 10.1002/0471140856.tx0432s42

Current Protocols in Toxicology

Current Protocols in Toxicology

How to Cite

Drobna, Z., Styblo, M. and Thomas, D. J. 2009. In Vitro Assays of Inorganic Arsenic Methylation. Current Protocols in Toxicology. 42:4.32:4.32.1–4.32.10.

Author Information

  1. 1

    Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina

  2. 2

    Center for Environmental Medicine, Asthma, and Lung Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina

  3. 3

    Pharmacokinetics Branch, Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina

Publication History

  1. Published Online: 1 NOV 2009
  2. Published Print: NOV 2009


Inorganic arsenic is extensively metabolized to produce mono-, di-, and trimethylated products. The formation of these metabolites produces a variety of intermediates that differ from inorganic arsenic in terms of patterns of distribution and retention and in toxic effects. In order to elucidate the pathway for arsenic methylation, it was necessary to develop a reliable in vitro assay system in which the formation of methylated metabolites could be monitored. Here, we describe an in vitro assay system that uses the postmicrosomal supernatant from rat liver as the source of the enzymatic activity that catalyzes methylation reactions. This system can be used to study the requirements for methylation reactions (e.g., identifying the donor of methyl groups) and for screening of compounds as potential activators or inhibitors of arsenic methylation. Curr. Protoc. Toxicol. 42:4.32.1-4.32.10. © 2009 by John Wiley & Sons, Inc.


  • arsenic;
  • rat liver;
  • postmicrosomal fraction;
  • methylation reactions;
  • methylated arsenicals