The effect of fentanyl on the transfer of small hydrophilic molecules across the blood-brain barrier was studied in rats by measuring the blood-brain transfer coefficient (K(i)) and the regional cerebral blood flow (rCBF) and by calculating the capillary permeability surface area product. In the control group (n = 14), after a femoral artery and vein were catheterized under isoflurane anesthesia, the rats were allowed to remain awake for 1.5 h before measuring K(i) (n = 8) using intravenous 14C-α-aminoisobutyric acid or rCBF (n = 6) using 14C-iodoantipyrine. In the fentanyl groups, rats were injected with 25 μg/kg (low dose) (n = 6) or 100 μg/kg (high dose) of fentanyl (n = 14), followed by a continuous infusion at a rate of 50 or 200 μg·kg-1·h-1, respectively. Their lungs were mechanically ventilated. The K(i) (low dose, n = 6; high dose, n = 8) and rCBF (high dose, n = 6) were measured 1 h after fentanyl infusion. The K(i) was lower in 9 of 13 brain regions in the low-dose fentanyl group and in 7 of 13 brain regions in the high-dose fentanyl group than in the control animals. The average value of K(i) in all the brain regions was 8.6 ± 4.6 μL·g-1μin-1 in the control group, 5.2 ± 2.9 μL·g-1·min-1 in the low-dose fentanyl group, and 5.7 ± 2.9 μL·g-1.min-1 in the high-dose fentanyl group. High-dose fentanyl did not significantly affect rCBF in any brain region studied. The value of the regional permeability-surface area product was similar to the corresponding regional K(i) in the groups studied. In conclusion, fentanyl decreased the transfer of small hydrophilic molecules across the blood brain barrier, as demonstrated by a decreased K(i) and permeability-surface area product, without significant changes in rCBF.
|Original language||English (US)|
|Number of pages||6|
|Journal||Anesthesia and analgesia|
|State||Published - 1992|
All Science Journal Classification (ASJC) codes
- Anesthesiology and Pain Medicine