Assessment of postischemic cerebral energy metabolism in cat by 31P NMR: the cumulative effects of secondary hypoxia and ischemia.

The sensitivity of cerebral energy metabolism to ischemic and hypoxic stresses following global cerebral ischemia was evaluated in a cat model using 31P nuclear magnetic resonance (NMR) spectroscopic methods. Complete global cerebral ischemia of 5 to 10 min in length was produced at 1 h intervals by reversible arterial occlusion, permitting continuous monitoring of NMR and EEG. Ischemia appeared to produce slightly more severe energy failure in animals that had previously experienced an ischemic injury. Preischemic hypoxia (5% O2 for 5 min) resulted in minor changes in the levels of phosphocreatine and intracellular inorganic phosphate, which were slightly amplified in animals that previously experienced ischemia.