Intramitochondrial adenine nucleotides and energy-linked functions of heart mitochondria.

G. K. Asimakis, L. A. Sordahl

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    Abstract

    Isolated rabbit heart mitochondria were incubated with varying amounts of inorganic pyrophosphate in 250 mM sucrose to specifically decrease the pool size of endogenous adenine nucleotides. The endogenous adenine nucleotide content decreased by as much as 80% as a result of this treatment. Phosphorylating respiration (state 3) declined from about 340 to 180 nAtoms O . min-1 . mg protein-1 over the full range of intramitochondrial adenine nucleotides measured (approx 7.5-1.5 nmol/mg protein). Uncoupled and nonphosphorylating (state 4) rates of respiration were not greatly affected by adenine nucleotide depletion. Respiratory activity of the adenine nucleotide-depleted mitochondria was enhanced by addition of exogenous adenosine 5'-triphosphate (ATP). Partial depletion (approx 40%) of the intramitochondrial adenine nucleotides resulted in an impaired ability of heart mitochondria to retain Ca2+. Premature Ca2+ efflux was associated with organelle swelling and altered energy coupling. Exogenous ATP or adenosine 5'-diphosphate (ADP) added prior to Ca2+ efflux restored Ca2+ retention in these mitochondria. Atractyloside inhibited the restoration of Ca2+ retention. This study indicates a significant role for endogenous adenine nucleotides in maintaining oxidative phosphorylation and Ca2+ transport in heart mitochondria. The results are discussed with regard to significance in ischemic heart damage.

    Original languageEnglish (US)
    JournalThe American journal of physiology
    Volume241
    Issue number5
    StatePublished - Nov 1981

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    Heart Mitochondria
    Adenine Nucleotides
    Mitochondria
    Atractyloside
    Oxidative Phosphorylation
    Respiratory Rate
    Organelles
    Adenosine Diphosphate
    Sucrose
    Respiration
    Proteins
    Adenosine Triphosphate
    Rabbits

    ASJC Scopus subject areas

    • Medicine(all)

    Cite this

    Intramitochondrial adenine nucleotides and energy-linked functions of heart mitochondria. / Asimakis, G. K.; Sordahl, L. A.

    In: The American journal of physiology, Vol. 241, No. 5, 11.1981.

    Research output: Contribution to journalArticle

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