Modifications of the permeability of the blood-brain barrier and local cerebral metabolism in pentobarbital- and ketamine-anaesthetized rats.

The state of deep surgical anaesthesia, induced by intraperitoneal injection of pentobarbital sodium (54 mg/kg) or ketamine hydrochloride (150 mg/kg) in the rat, was accompanied by a significant reduction in the permeability of the blood-brain barrier evaluated by calculating a unidirectional blood-to-brain constant (Ki) for the circulating tracer [14C]alpha-aminoisobutyric acid. Pentobarbital-induced anaesthesia was also characterized by a widespread and marked depression of local cerebral glucose utilization; on the contrary, when rats were anaesthetized with ketamine, cerebral glucose utilization increased in the striatum and hippocampus and decreased in the cerebellum and brain-stem. It is suggested, as a hypothesis, that two different mechanisms, depending on the kind of the anaesthetic drug used, may be involved in the changes in the permeability of the blood-brain barrier, observed in anaesthetized animals: (a) a neurogenic component; (b) a direct interaction of the anaesthetic with elements of the microvasculature.