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SYNTHETIC AMINO ACIDS AND THE NATURE OF l ‐DOPA TRANSPORT AT THE BLOOD‐BRAIN BARRIER
Author(s) -
Wade L. A.,
Katzman R.
Publication year - 1975
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1975.tb04415.x
Subject(s) - isobutyric acid , amino acid , alanine , chemistry , stereochemistry , blood–brain barrier , metabolism , biochemistry , biophysics , biology , neuroscience , central nervous system
—The blood‐brain barrier transport of amino acids has been measured using the carotid injection technique in the rat. The synthetic amino acids, 2‐aminobicyclo(2,2,1)heptane‐2‐carboxylic acid (BCH) and α‐(methylamino)isobutyric acid (MeAIB), were model substrates in the Ehrlich cell for the leucine (L) and alanine (A) neutral amino acid transport mechanisms, respectively. The uptake (±)b‐[carboxyl‐ 14 C]BCH at the same rate for the five brain regions tested suggested a similarity between regions for the L transport mechanism. At injectant concentrations of 0·1 m m (similar to naturally occurring aromatic neutral amino acids), BCH was mainly taken up by a saturable mediated transport mechanism ( K 1 , 0·16 m m and V max , 0·03/μmol/g per min). At higher concentrations, uptake by a nonsaturable or diffusional mechanism could be demonstrated. When BCH was added as a second amino acid to l ‐[3‐ 14 C]DOPA, the saturable component of l ‐DOPA transport was significantly inhibited. MeAIB had no measurable effect on the rate of l ‐DOPA transport. These results suggested that the mediated transport mechanism for l ‐DOPA at the cerebral capillaries is similar to the l ‐neutral amino acid transport system.