Facilitated transport of prostaglandins across the blood—cerebrospinal fluid and blood—brain barriers

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Abstract
Ventriculo-cisternal perfusions were performed on rabbits with artificial cerebrospinal fluid containing blue dextran and 3H-labeled prostaglandin F2.alpha. ([3H]PGF2.alpha.). In order to study the nature of prostaglandin transfer across the blood-brain barrier, high concentrations of PGF2.alpha. or potential PG transport inhibitors were added to the perfusion fluid after the normal rate of [3H]PGF2.alpha. clearance was established. The [3H]PGF2.alpha. clearance was inhibited by 10-6-10-3 M PGF2.alpha., PGF2.beta., probenecid, iodipamide or bromcresol green but not by perchlorate. The 3H content of the brain, relative to the 3H-activity in the ventricular system, was increased by high concentrations of PGF2.alpha., iodipamide or bromcresol green. The removal of PGs from brain extracellular fluids is mediated by saturable, facilitated transport processes across both the choroidal and extrachoroidal regions of the blood-brain barrier system. In the case of the mammalian brain, such facilitated PG transport appears to be the primary mechanism for the termination of the action of these potent, endogenously produced autacoids.