Transendothelial Transport and Its Role in Therapeutics

Table 5

Major amino acid transporters occur at blood brain barrier.

Type of amino acid	Transporter	Location	Influx or efflux	References
Influx	Amino acid carrier system or alanine preferring transporter and 1-dihydroxy-phenylalanine (1-DOPA).	Antiluminal surface of the brain capillary		[123, 124]
Alanine, glycine, proline, and -aminobutyric acid	A-(alanine-preferring-) system carrier	Antiluminal surface of the brain capillary	Influx	[64, 125]
Small neutral amino acids, (system A), L-alanine, L-asparaginine, L-cysteine, glutamine, glycine, L-histidine, L-proline, and L-serine	A-system carrier, secondary active transport	Antiluminal surface of the brain capillary	Influx, efflux	[126]
Basic, acidic and -amino acids; glutamate, aspartate, and -amino acid taurine	Simple carrier system	Membrane receptors	Influx	[127, 128]
L-proline	Na^+-gradient-dependent transport	Membrane receptors		[129]
Large neutral amino acid (system L) (LAT1 and LAT2)	Facilitated diffusion	Branched or aromatic side chain aminoacids; L-DOPA, -methyl-DOPA, gabapentin, L-leucine, melphalan, L-phenylalanine, L-tryptophan, and L-tyrosine	Influx
Na^+-LNAA neutral amino Acid	A-system carrier, secondary active transport	Alanine, glycine, histidine, isoleucine, leucine, methionine, phenylalanine, threonine, tryptophan, tyrosine, and valine	Efflux
Neutral amino acid system ASC) (ASCT1 and ASCT2)	A-system carrier, secondary active transport	L-alanine, L-aspartate, L-cysteine,; L-glutamate, glycine, L-isoleucine, L-leucine, L-methionine, L-serine, L-threonine, and L-valine	Efflux
System B0+	Simple carrier system	Basic and neutral amino acids	Efflux
System	Simple carrier system	-alanine, taurine
Basic amino acid	Simple carrier system	Lysine	Influx
Acidic amino acid; (system x−)	Facilitated diffusion	L-aspartate, L-glutamate
System X−	Simple carrier system	L-aspartate, L-glutamate	Efflux
N-system	A-system carrier, Secondary active transport	L-asparaginine, glutamine, glutamate, L-histidine, and L-serine
Excitatory amino; acid (EAAT1-3)	Simple carrier system	Aspartate, glutamate	Influx
Amine (cation,; system y+)	Active transport	L-arginine, choline, L-cysteine, lysine, and ornithine	Influx
System T	Simple carrier system	Thyroid hormones T3 and T4