The metabolic consequences of hydroperoxide perfusion on the isolated rat heart.
Perfusion of rat hearts with Krebs-Henseleit bicarbonate buffer containing low concentrations of hydrogen peroxide or t-butylhydroperoxide (50-500 microM) caused an imbalance in the relative synthesis versus utilization rates of ATP, leading to a net hydrolysis of ATP and phosphocreatine. Hydrogen peroxide also caused an 80% inactivation of glyceraldehyde-3-phosphate dehydrogenase, resulting in an inhibition of glycolysis and a rapid accumulation of sugar phosphates as detected with 31P-NMR spectroscopy. This inhibition was partially reversible with peroxide-free perfusion, resulting in a cessation of high-energy-phosphate hydrolysis and a decrease in the accumulated inorganic phosphate and sugar phosphate. t-Butylhydroperoxide toxicity was irreversible. Providing an alternative, non-glycolytic substrate (butyrate) did not protect against the toxicity of hydrogen peroxide, but altered the relative importance of sugar phosphate formation versus ATP hydrolysis. Experiments with heart homogenates in vitro suggest that the inhibition of glyceraldehyde-3-phosphate dehydrogenase is a consequence of a direct reaction of the enzyme with hydrogen peroxide or one of its metabolites. Hearts subjected to total global ischemia (10-20 min), followed by reperfusion with oxygenated buffer, showed no detectable inactivation of glyceraldehyde-3-phosphate dehydrogenase, indicating that ischemia and reperfusion do not result in the production of high global concentrations of hydrogen peroxide.
Chatham
J C
JC
Department of Biochemistry, University of Oxford.
Gilbert
H F
HF
Radda
G K
GK
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002087:Butyrates / Q000378:metabolism; D020148:Butyric Acid; D005947:Glucose / Q000378:metabolism; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000032:analysis / Q000037:antagonists & inhibitors; D006321:Heart / Q000187:drug effects*; D006861:Hydrogen Peroxide / Q000633:toxicity*; D008297:Male; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000378:metabolism; D010545:Peroxides / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D020122:tert-Butylhydroperoxide
D002087:Butyrates; D010545:Peroxides; D020148:Butyric Acid; D000255:Adenosine Triphosphate; D020122:tert-Butylhydroperoxide; D006861:Hydrogen Peroxide; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D005947:Glucose