title: Influence of iodinated contrast media on the activities of histamine inactivating enzymes diamine oxidase and histamine N-methyltransferase in vitro.
abstract: BACKGROUND
  Iodinated contrast media can cause pseudoallergic reactions associated with histamine release in significant numbers of patients. To clarify whether these adverse reactions may be aggravated by a compromised histamine catabolism we asked if radiographic contrast agents in vitro inhibit the histamine inactivating enzymes diamine oxidase (DAO) and histamine N-methyltransferase (HMT).
  
  
  METHODS
  Nine iodinated contrast agents were tested in vitro. Following pre-incubation of purified porcine kidney DAO and recombinant human HMT with 0.1-10mM of the respective contrast medium (H2O and specific inhibitors of DAO and HMT as controls) enzyme activities were determined by using radiometric micro assays.
  
  
  RESULTS
  None of the contrast media irrespective of their structure showed significant inhibition of the activities of DAO and HMT. Pre-incubation of the enzymes with specific inhibitors led to complete inhibition of the respective enzymatic activity.
  
  
  CONCLUSIONS
  The iodinated contrast media tested in vitro did not exhibit inhibition of histamine converting enzymes at physiologically relevant concentrations. However due to the in vitro character of this study these results do not directly reflect the in vivo situation.
authors.affiliation: Radiologisches Institut, Universität Erlangen-Nürnberg, Maximiliansplatz 1, D-91054 Erlangen, Germany. Electronic address: michael.kuefner@uk-erlangen.de.
authors.forename: M A
authors.initials: MA
authors.lastname: Kuefner
authors.affiliation: Molekularbiologisches Labor, Universitätsklinik für Visceral-, Transplantations- und Thoraxchirurgie, Medizinische Universität Innsbruck, Schöpfstraße 41, A-6020 Innsbruck, Austria.
authors.forename: J
authors.initials: J
authors.lastname: Feurle
authors.affiliation: Universitätsklinik für Radiologie 1, Medizinische Universität Innsbruck, Anichstr. 35, A-6020 Innsbruck, Austria.
authors.forename: J
authors.initials: J
authors.lastname: Petersen
authors.affiliation: Radiologisches Institut, Universität Erlangen-Nürnberg, Maximiliansplatz 1, D-91054 Erlangen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Uder
authors.affiliation: Molekularbiologisches Labor, Universitätsklinik für Visceral-, Transplantations- und Thoraxchirurgie, Medizinische Universität Innsbruck, Schöpfstraße 41, A-6020 Innsbruck, Austria.
authors.forename: H G
authors.initials: HG
authors.lastname: Schwelberger
mesh_terms: D006631:Amine Oxidase (Copper-Containing) / Q000378:metabolism*; D000818:Animals; D003287:Contrast Media / Q000009:adverse effects* / Q000378:metabolism; D006632:Histamine / Q000378:metabolism*; D006637:Histamine N-Methyltransferase / Q000378:metabolism*; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology / Q000378:metabolism; D066298:In Vitro Techniques; D007455:Iodine / Q000009:adverse effects* / Q000276:immunology / Q000378:metabolism; D013552:Swine
chemical_list: D003287:Contrast Media; D006632:Histamine; D007455:Iodine; D006631:Amine Oxidase (Copper-Containing); D006637:Histamine N-Methyltransferase
keywords: Diamine oxidase; Histamine N-methyltransferase; Histamine metabolism; Hypersensitivity reactions; Iodinated contrast media