ATP and pH predictors of histologic damage following global cerebral ischemia in the rat

In vivo changes of high energy phosphates and pH were determined with 31P NMR spectroscopy in rats subjected to symmetric or asymmetric partial global ischemia with reperfusion. Tissue damage was assessed by histology. ATP depletion, following PCr depletion, developed shortly after the onset of ischemia. In prolonged ischemia reperfusion was not followed with full recovery. APT depletion of more than 20% during reperfusion was associated with histologic damage; marked necrosis was associated with 50% reduction. Although during ischemia, severe persisting intracellular acidosis developed sometimes, and it was also associated with tissue damage, it did not appear to elicit tissue damage independently of the ATP depletion. Splitting of the Pi peak was useful in predicting heterogeneous distribution of the necrosis, thus it can reflect a heterogeneous distribution of the intracellular pH.