Suppression of rabbit myocardial xanthine dehydrogenase activity by an endogenous compound

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4 Scopus citations


Xanthine dehydrogenase (XDH) is an important precursor to the oxygen radical producing enzyme xanthine oxidase (XO). We found that the apparent activity of rabbit myocardial XDH increased from 2 ± 1 to 50 ± 3 μU/g (P<0.05) following extraction of tissue homogenate with butanol. Further studies suggested that the basis for this observation was a high molecular weight compound which consumes the XDH cofactor, NAD+. Addition of myocardial homogenate to exogenous NAD+ resulted in depletion of NAD+ and concomitant formation of an additional compound (peak A). Both NAD+ consumption and peak A formation were abrogated by prior extraction of homogenate with butanol. Separation of myocardial homogenate by Sephadex chromatography revealed a high molecular weight compound which suppressed activity of purified milk XDH but not xanthine oxidase (XO). This activity co-eluted with the ability of myocardial homogenate to consume added NAD+ and form peak A. The NAD+-consuming activity was heat and acid-labile. In addition, nicotinamide was both a product and an inhibitor of the NADase activity, consistent with the existence of a previously described myocardial glycohydrolase. Extraction of tissue with butanol may be necessary to detect low levels of XDH activity in vitro.

Original languageEnglish (US)
Pages (from-to)125-132
Number of pages8
JournalJournal of Molecular and Cellular Cardiology
Issue number2
StatePublished - Feb 1994


  • 1-butanol
  • Glycohydrolase
  • HPLC
  • Ischemia-reperfusion
  • Nicotinamide adenine dinucleotide
  • Xanthine oxidase

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine


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