Brain pH in focal cerebral ischemia and the protective effects of barbiturate anesthesia.

Intracellular brain pH was measured with a lipid-soluble, pH-sensitive fluorescent indicator in 16 squirrel monkeys. Eight of these were under halothane anesthesia and eight under barbiturate anesthesia. Measurements were taken before, during, and after focal incomplete ischemia. Brain pH following 3 h of cerebral focal ischemia changed from a normal value of 7.0 to 6.5 and 6.2 in animals studied under barbiturate and halothane anesthesia, respectively. Brain pH returned toward normal after flow was restored in animals under barbiturate anesthesia but continued to deteriorate in animals under halothane anesthesia.