EFFECTS OF SHOCK AND ANOXIA ON NUCLEOTIDES AND CREATINE PHOSPHATE IN THE ISOLATED BRAIN OF THE DOG1

Surgically isolated canine brains were maintained with compatible donor blood from an extracorporeal perfusion system. Small samples of frozen cerebral cortex were removed with a newly-developed Freon cryoprobe and were analysed for acid-soluble nucleotides, creatine phosphate and inorganic phosphate. Most animals were in the early stages of shock unless they had received preoperative α-adrenergic blockade with phenoxybenzamine hydrochloride (Dibenzyline). Values for high-energy phosphates were in the normal range only when the animal had been premedicated with phenoxybenzamine hydrochloride. During a 4-min period of anoxia (induced by blood which had been equilibrated with 95% N₂ and 5% CO₂), the cerebral cortex rapidly became iso-electric, and the levels of creatine phosphate and ATP decreased concomitantly with increases in levels of ADP and P_i. These electrical and chemical changes were rapidly and completely reversed by reoxygenation. The levels of high-energy phosphates provide a sensitive criterion of functional adequacy that may be more readily quantitated than cerebral electrical activity (EEG). EEG recovery did not correlate closely with rephosphorylation.