title: Chronic magnesium deficiency decreases tolerance to hypoxia/reoxygenation injury in mouse heart.
abstract: OBJECTIVE
  Magnesium (Mg) deficiency has been reported to be associated with the development of the metabolic syndrome, cardiovascular diseases, and sudden death. We examined the influence of chronic Mg deficiency on cardiac tolerance to hypoxia/reoxygenation injury.
  
  
  METHODS
  Mice were fed an Mg-deficient diet for 4 weeks, and then their hearts were excised for Langendorff perfusion experiments. The levels of total Mg in the blood and heart were quantified by atomic absorption spectrometry.
  
  
  RESULTS
  In Mg-deficient mice, the Mg concentration in whole blood was markedly decreased; however, that in the heart remained unchanged. When the hearts of control mice were exposed to hypoxia/reoxygenation, removal of extracellular Mg from a normal Krebs solution containing 1.2 mM Mg resulted in a significant decrease in the recovery of the tension-rate product (TRP) upon reoxygenation. In Mg-deficient mice, the recovery of TRP in the heart was reduced significantly in the absence of extracellular Mg compared to that in controls. The addition of Mg to the perfusate did not improve TRP recovery. During hypoxia/reoxygenation, cardiac damage evaluated by myocardial aspartate amino transferase (AST) release was greater in hearts of Mg-deficient mice than in that of control mice.
  
  
  CONCLUSIONS
  These results indicate that chronic Mg deficiency causes severe hypomagnesemia and a decrease in cardiac tolerance to hypoxia, without changing the intracellular Mg content. The decreased tolerance to hypoxia was not affected by the presence or absence of extracellular Mg, suggesting that some intracellular metabolic abnormalities develop in the cardiac myocytes of Mg-deficient mice.
authors.affiliation: Department of Physiology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan. makinow@juntendo.ac.jp
authors.forename: Makino
authors.initials: M
authors.lastname: Watanabe
authors.forename: Atsuko
authors.initials: A
authors.lastname: Shinohara
authors.forename: Takehisa
authors.initials: T
authors.lastname: Matsukawa
authors.forename: Momoko
authors.initials: M
authors.lastname: Chiba
authors.forename: Jinrong
authors.initials: J
authors.lastname: Wu
authors.forename: Takafumi
authors.initials: T
authors.lastname: Iesaki
authors.forename: Takao
authors.initials: T
authors.lastname: Okada
mesh_terms: D000818:Animals; D001219:Aspartate Aminotransferases / Q000378:metabolism; D015687:Cell Hypoxia; D008274:Magnesium / Q000097:blood / Q000378:metabolism*; D008275:Magnesium Deficiency / Q000150:complications*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009206:Myocardium / Q000473:pathology*; D010100:Oxygen / Q000008:administration & dosage* / Q000378:metabolism; D013054:Spectrophotometry, Atomic
chemical_list: D001219:Aspartate Aminotransferases; D008274:Magnesium; D010100:Oxygen