Amino acid assignment to one of three blood-brain barrier amino acid carriers

Am J Physiol. 1976 Jan;230(1):94-8. doi: 10.1152/ajplegacy.1976.230.1.94.


The percentages of 22 14C-labeled amino acids remaining in rat brain 15 s after carotid injection were measured relative to a simultaneously injected diffusible internal standard, 3HOH. The injected solution also contained a nondiffusible internal standard, [113mIn]EDTA to correct for incomplete brain blood compartment washout. Self-inhibition and cross-inhibition was demonstrated by inclusion of unlabeled amino acids and carboxylic acids. All amino acids tested, excluding proline, alanine, and glycine, could be assigned to one, and only one, blood-brain barrier carrier system. The neutral carrier system transported phenylalanine, leucine, tyrosine, isoleucine, methionine, tryptophane, valine, DOPA, cysteine, histidine, threonine, glutamine, asparagine, and serine. Affinity for a basic amino acid carrier system was demonstrated for arginine, ornithine, and lysine. A third, low-capacity independent carrier system transporting aspartic and glutamic acids was demonstrated.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amides / pharmacology
  • Amino Acids / metabolism*
  • Animals
  • Binding, Competitive
  • Biological Transport, Active
  • Blood-Brain Barrier*
  • Carrier Proteins / metabolism*
  • Female
  • Fumarates / pharmacology
  • Lactates / pharmacology
  • Male
  • Pyruvates / pharmacology
  • Rats
  • Stereoisomerism
  • Succinates / pharmacology


  • Amides
  • Amino Acids
  • Carrier Proteins
  • Fumarates
  • Lactates
  • Pyruvates
  • Succinates