Table 1. BBB carrier-mediated transporters.
| Carrier | Substrate | Genea product | Kmb (uM) | Vmaxb,c (nmol/min/g) | Ccapd (pmol/mgp) | Vmax:Cape (molecules per second) |
|---|---|---|---|---|---|---|
| Glucose | 𝒟-glucose | GLUT1 (SLC2A1) | 11,000±1,400 | 1,420±140 | 139±46 | 600 |
| Monocarboxylic acid | ℒ-lactic acid | MCT1 (SLC16A1) | 1,800±600 | 91±35 | 2.3±0.8 | 2,300 |
| Neutral amino acid | ℒ-phenyl-alanine | LAT1 (SLC7A5) | 26±6 | 22±4 | 0.43±0.09 | 3,000 |
| Basic amino acid | ℒ-arginine | CAT1 (SLC7A1) | 40±24 | 5±3 | 1.1±0.2 | 270 |
| Purine nucleoside | Adenosine | CNT2 (SLC28A2) | 25±3 | 0.75±0.08 | <0.14 | ND |
BBB, blood–brain barrier.
a
Solute carrier (SLC) group of transporter genes.
b
From Pardridge.47
c
Per gram wet brain in the rat.
d
From Uchida et al.48 Data reported per mg isolated human brain capillary protein.
e
Vmax/Ccap ratio is the transporter turnover number, which is the number of substrate molecules transported per second by a single transporter molecule, and is based on 0.14 mg capillary protein per gram wet brain; it is assumed that 50% of the total capillary transporter is expressed on the endothelial luminal membrane; nd=not determined.