Metabolic effects of kynurenate during reversible forebrain ischemia studied by in vivo31P-nuclear magnetic resonance spectroscopy

Abstract The metabolic effects of kynurenate, an endogeneous excitatory amino acid antagonist, were studied by in vivo 31 P-NMR spectroscopy before, during and after reversible forebrain ischemia in the rat. Kynurenate had no effect on cerebral metabolism before ischemia. During a 30-min ischemia, kynurenate protected against the decrease in phosphocreatine (up to−55 ± 3%vs−73 ± 3% in the reference group) and the increase in inorganic phosphate (up to+479 ± 39%vs+805 ± 66%), whereas ther was no statistical difference in the decrease in intracellular pH (up to6.37 ± 0.05vs6.30 ± 0.03) and ATP (up to−60 ± 3%vs−60 ± 7%). The recovery of PCr, i and pH i to control levels during recirculation was faster in the treated group than in the reference group, whereas the time course of ATP recovery was similar in both groups. We conclude that kynurenate protects against neuronal loss, as previously reported, by mechanisms other than metabolic protection.