2,3-Butanedione monoxime unmasks Ca2+-induced NADH formation and inhibits electron transport in rat hearts

Russell C. Scaduto, Lee W. Grotyohann

    Research output: Contribution to journalArticlepeer-review

    14 Scopus citations

    Abstract

    We used 2,3-butanedione monoxime (BDM) to suppress work by the perfused rat heart and to investigate the effects of calcium on NADH production and tissue energetics. Hearts were perfused with buffer containing BDM and elevated perfusate calcium to maintain the rates of cardiac work and oxygen consumption at levels similar to those of control perfused hearts. BDM plus calcium hearts displayed higher levels of NADH surface fluorescence, indicating calcium activation of mitochondrial dehydrogenases. These hearts, however, displayed 20% lower phosphocreatine levels. BDM suppressed the rates of state 3 respiration of isolated mitochondria. Uncoupled respiration was suppressed to a lesser degree, and the state 4 respiration rates were not affected. Double-inhibitor experiments with liver mitochondria using BDM and carboxyatractyloside (CAT) were used to identify the site of inhibition. BDM at low levels (0-5 mM) suppressed respiration. In the presence of CAT at levels that inhibit respiration by 60%, low levels of BDM were without effect. Because these effects were not additive, BDM does not inhibit adenine nucleotide transport. This was supported by an assay of adenine nucleotide transport in liver mitochondria. BDM did not inhibit ATP hydrolysis by submitochondrial particles but strongly suppressed reversed electron transport from succinate to NAD+. Oxidation of NADH by submitochondrial particles was inhibited by BDM but oxidation of succinate was not. We conclude that BDM inhibits electron transport at site 1.

    Original languageEnglish (US)
    Pages (from-to)H1839-H1848
    JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
    Volume279
    Issue number4 48-4
    DOIs
    StatePublished - 2000

    All Science Journal Classification (ASJC) codes

    • Physiology
    • Cardiology and Cardiovascular Medicine
    • Physiology (medical)

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