[In vivo aminoacid transport in the brain of the rat with porto-caval anastomosis (author's transl)].

Cerebral capillary permeability to L-amino acids was studied in rats submitted to porto-caval anastomosis 4 weeks before. The short-term intracarotidal injection technique described by Oldendorf was used throughout. Neutral amino acid permeability appeared to be greatly increased, the most important enhancement being for the tryptophan. On the opposite, basic amino acids showed a net decrease in their rate of passage from blood to the brain. No changes were observed for GABA and glutamic acid. These data suggest a marked modification of the permeability of the cerebral capillary membranes in the rat with chronic portocaval anastomosis. Moreover, such alterations are selective for the different amino acid transport classes. Competitive inhibition decreased the permeability of methionine at the same level in both control and experimental animals: therefore, the neutral amino acid increased entry into the rat brain after porto-caval shunt is due to an enhancement of the transport processes.