Acute cerebral ischaemia: concurrent changes in cerebral blood flow, energy metabolites, pH, and lactate measured with hydrogen clearance and 31P and 1H nuclear magnetic resonance spectroscopy. II. Changes during ischaemia.

CBF has been measured with the hydrogen clearance technique in the two cerebral hemispheres of the gerbil under halothane anesthesia. This has been correlated with changes in local pH, tissue lactate, and phosphorus energy metabolites measured in the same animals with 1H and 31P nuclear magnetic resonance spectroscopy. We demonstrate a threshold flow value for the metabolic changes associated with energy failure at a level similar to the values previously reported for electrical failure and tissue water accumulation, but higher than that associated with breakdown of extracellular potassium homeostasis.