Anoxia followed by hyperoxia: in vivo 31-P NMR of cat brain.

In vivo 31P NMR spectroscopy was performed on a cat brain subjected to an extended period of anoxia followed by restoration of oxygen. High energy phosphate spectra were continuously obtained and pH measured. Following the onset of anoxia, phosphocreatine and ATP peaks decreased with a concomitant increase in inorganic phosphate. Following 34 min ventilation on 100% N2, the animal was ventilated on 100% O2. The spectral content progressively changed, inorganic phosphate decreased and ATP increased with the spectrum closely resembling that of control. Our results suggest that the absence of NMR detectable ATP signal cannot be interpreted as an irreversable change in cellular metabolic function.