Cytosolic free magnesium levels in ischemic rat heart

E. Murphy, C. Steenbergen, L. A. Levy, B. Raju, R. E. London

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186 Scopus citations


Changes in cytosolic free magnesium ion concentration (Mg(i)) during myocardial ischemia were measured by 19F NMR in perfused rat hearts loaded with fluorine-labeled derivatives of the magnesium chelator o-aminophenol-N,N,O-triacetate. The perfused rat hearts were loaded intracellularly with the appropriate magnesium indicator by perfusion with 200-400 ml of Krebs-Henseleit buffer containing 5 μM acetoxymethyl ester of the indicator. Basel Mg(i) concentrations measured by three different indicators averaged 0.85 ± 0.10 mM (n = 9) and showed no correlation with the K(D) of the indicator used. 31P NMR measurements of the magnesium-dependent shift between α- and β-phosphates of ATP demonstrate that there is no measurable lowering of Mg(i) during loading with fluorinated o-aminophenol-N,N,O-triacetate. Between 10 and 15 min of ischemia. Mg(i) rose nearly 3-fold to 2.1 ± 0.4 mM. This increase in Mg(i) occurred over the same time course as the decrease ATP. After 20 min of reperfusion with Krebs-Henseleit buffer, Mg(i) declined to 1.5 ± 0.5 mM. This sustained elevation of Mg(i) above basal levels may inhibit calcium release from sarcoplasmic reticulum, thereby contributing to the well documented impairment of mechanical function that occurs after a reversible period of ischemia.

Original languageEnglish (US)
Pages (from-to)5622-5627
Number of pages6
JournalJournal of Biological Chemistry
Issue number10
StatePublished - 1989
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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