Hydrogen peroxide-induced oxidative stress to the mammalian heart-muscle cell (cardiomyocyte): lethal peroxidative membrane injury.
Oxidative stress induced by hydrogen peroxide (H2O2) may contribute to the pathogenesis of ischemic-reperfusion injury in the heart. For the purpose of investigating directly the injury potential of H2O2 on heart muscle, a cellular model of H2O2-induced myocardial oxidative stress was developed. This model employed primary monolayer cultures of intact, beating neonatal-rat cardiomyocytes and discrete concentrations of reagent H2O2 in defined, supplement-free culture medium. Cardiomyocytes challenged with H2O2 readily metabolized it such that the culture content of H2O2 diminished over time, but was not depleted. The consequent H2O2-induced oxidative stress caused lethal sarcolemmal disruption (as measured by lactate dehydrogenase release), and cardiomyocyte integrity could be preserved by catalase. During oxidative stress, a spectrum of cellular derangements developed, including membrane phospholipid peroxidation, thiol oxidation, consumption of the major chain-breaking membrane antiperoxidant (alpha-tocopherol), and ATP loss. No net change in the protein or phospholipid contents of cardiomyocyte membranes accompanied H2O2-induced oxidative stress, but an increased turnover of these membrane constituents occurred in response to H2O2. Development of lethal cardiomyocyte injury during H2O2-induced oxidative stress did not require the presence of H2O2 itself; a brief "pulse" exposure of the cardiomyocytes to H2O2 was sufficient to incite the pathogenic mechanism leading to cell disruption. Cardiomyocyte disruption was dependent upon an intracellular source of redox-active iron and the iron-dependent transformation of internalized H2O2 into products (e.g., the hydroxyl radical) capable of initiating lipid peroxidation, since iron chelators and hydroxyl-radical scavengers were cytoprotective. The accelerated turnover of cardiomyocyte-membrane protein and phospholipid was inhibited by antiperoxidants, suggesting that the turnover reflected molecular repair of oxidized membrane constitutents. Likewise, the consumption of alpha-tocopherol and the oxidation of cellular thiols appeared to be epiphenomena of peroxidation. Antiperoxidant interventions coordinately abolished both H2O2-induced lipid peroxidation and sarcolemmal disruption, demonstrating that an intimate pathogenic relationship exists between sarcolemmal peroxidation and lethal compromise of cardiomyocyte integrity in response to H2O2-induced oxidative stress. Although sarcolemmal peroxidation was causally related to cardiomyocyte disruption during H2O2-induced oxidative stress, a nonperoxidative route of H2O2 cytotoxicity was also identified, which was expressed in the complete absence of cardiomyocyte-membrane peroxidation. The latter mode of H2O2-induced cardiomyocyte injury involved ATP loss such that membrane peroxidation and cardiomyocyte disruption on the one hand and cellular de-energization on the other could be completely dissociated.(ABSTRACT TRUNCATED AT 400 WORDS)
Janero
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Research Department, CIBA-GEIGY Corporation, Summit, New Jersey 07901.
Hreniuk
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D
Sharif
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HM
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D005978:Glutathione / Q000378:metabolism; D006321:Heart / Q000187:drug effects*; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D015227:Lipid Peroxidation; D008565:Membrane Proteins / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012508:Sarcolemma / Q000378:metabolism; D014810:Vitamin E / Q000378:metabolism
D008565:Membrane Proteins; D010743:Phospholipids; D014810:Vitamin E; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D005978:Glutathione