Lactate in the cerebrospinal fluid and pressure-flow relationships in canine cerebral circulation.

Lactate in the Cerebrospinal Fluid and Pressure-Flow Relationships in Canine Cerebral Circulation • In 11 dogs, lactate and pH in the cerebrospinal fluid and in the arterial and the venous blood were measured during stepwise reductions of the arterial blood pressure by controlled bleeding. Increase in lactate and decrease in pH of the cerebrospinal fluid occurred with lowering of the mean arterial blood pressure even within the pressure ranges of 110 to 50 mm Hg, where autoregulation was fairly observed. Reductions of the blood pressure by 20 to 40 mm Hg led to a significant increase in lactate, and reductions by 60 mm Hg led to a significant decrease in pH of the cerebrospinal fluid. The relation of decrease in pH and increase in lactate was linear, suggesting that lactacidosis occurred. In the arterial and the venous blood, a marked increase in lactate and decrease in pH also were observed. Lactate concentrations of the cerebral venous blood were significantly higher than those of the arterial blood until the arterial blood pressure had been reduced below 70 mm Hg. Therefore, it was suggested that increase in lactate of the cerebrospinal fluid might be attributed solely to increase in lactate of the brain tissue, so far as the blood pressure was not lowered below 70 mm Hg at least. The possibility of participation of the cerebrospinal fluid lactacidosis in autoregulation of the cerebral blood flow was discussed. Additional