Low extracellular magnesium induces intracellular free Mg deficits, ischemia, depletion of high-energy phosphates and cardiac failure in intact working rat hearts: a 31P-NMR study

Biochim Biophys Acta. 1993 Oct 20;1182(3):329-32. doi: 10.1016/0925-4439(93)90077-e.

Abstract

Hemodynamic and 31P-NMR spectroscopic studies were performed on intact, perfused working rat hearts exposed to low (0.3 mM) extracellular Mg([Mg2+]o). Low [Mg2+]o perfusion resulted in rapid and significant falls in cardiac output, coronary flow, stroke volume, developed pressure and the rate-pressure product. Concomitant with this O2 consumption decreased and lactate production increased. Hearts perfused with 0.3 mM, instead of 1.2 mM, [Mg2+]o exhibited significant reductions in [ATP], [PCr], intracellular free Mg ([Mg2+]i), and pHi; a marked rise in intracellular Pi corresponding to a precipitous fall in the cytosolic phosphorylation potential was seen. Reintroduction of 1.2 mM [Mg2+]o failed to reestablish either normal hemodynamics, or high-energy phosphates and intracellular Pi, suggesting irreversible myocyte injury. These observations are consistent with the tenet that low [Mg2+]o can result in marked reduction in oxygen and substrate delivery to the cardiac myocytes, probably as a result of coronary vasoconstriction.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Coronary Disease / etiology*
  • Hemodynamics
  • Hydrogen-Ion Concentration
  • Magnesium / analysis*
  • Magnesium Deficiency / complications*
  • Magnesium Deficiency / metabolism
  • Magnetic Resonance Spectroscopy
  • Male
  • Myocardium / metabolism*
  • Perfusion
  • Phosphates / metabolism*
  • Rats
  • Rats, Wistar

Substances

  • Phosphates
  • Magnesium