Table II.
Comparison of ABC Transporter Protein Expression per Surface Area of the Blood-Brain Barrier (BBB) and the Blood-Spinal Cord Barrier (BSCB) Between Humans and Rats
| Protein expression (PEL) | (fmol/cm2 surface area of the barrier) | ||||
|---|---|---|---|---|---|
| ABCA8/ABCA8 | MDR1/ABCB1 | BCRP/ABCG2 | |||
| humans | humans | rats | humans | rats | |
| Blood-brain barrier (BBB) | |||||
| Cerebral cortex | 8.62 ± 2.66 | 50.3 ± 28.6 | 41.5 ± 17.3 | ||
| Cerebral white matter | 7.54 ± 1.10 | 33.1 ± 15.6 | 30.8 ± 6.3 | ||
| Cerebrum | 497 ± 15 | 217 ± 2 | |||
| Blood-spinal cord barrier (BSCB) | |||||
| Thoracic spinal cord | 10.9 ± 6.7 | 13.7 ± 7.8 | 15.0 ± 11.2 | ||
| Spinal cord | 398 ± 26 | 252 ± 3 | |||
Values were cited from supplemental Table S3 in reference (5). For the unit conversion from (pmol/g wet tissue weight) to (fmol/cm2 surface area), the following values were used: 180 cm2/g wet tissue for cortex in humans (59), 100 cm2/g tissue for white matter in humans (59), and 141 cm2/g tissue for the spinal cord in humans (5), 140 cm2/g tissue weight for the whole cerebrum in rats (60), and 159 cm2/g wet tissue for the spinal cord in rats (61), respectively. The average of the frontal cortex and temporal/parietal cortex region of 3 donors, and that of the spinal cord of 4 donors are shown with the standard deviation (SD) for humans. Capillaries were isolated from the pooled rat brains (n = 9) and spinal cord (n = 18). The averages are shown with the standard error of the mean (S.E.M) for rats