Drug uptake by brain. II. Barbiturate uptake alters the transport of amino acids in vitro(1).

1. Valine and leucine uptake into mouse brain slices was stimulated by 1 to 4 mM phenobarbital and pentobarbital. Greater concentrations of these two barbiturates inhibited the transport of these amino acids. Barbital, isobarbituric acid, and 5-nitrobarbituric acid had no effect, while amobarbital and secobarbital produced only inhibition of uptake. 2. Transport of glutamate and aspartate was unaffected by phenobarbital concentrations that inhibited uptake of lysine and alpha-aminoisobutyric acid. 3. Changes in the Na+ and K+ content of the slices were not related to stimulation of valine or leucine uptake. 4. There was no concentrative uptake of phenobarbital by brain slices. The partially saturable uptake of pentobarbital was not by active transport, because the uptake increased after heating brain, liver, or kidney slices to 95 degrees for 10 min. 5. This study shows that individual members of a pharmacologically related group may have specific effects on a composite physiological function (amino acid transport) of brain tissue.