Permeability of the blood-brain barrier is not changed by vasoactive doses of arachidonic acid or prostaglandins in rats.

Charles River, Sprague-Dawley rats of both sexes were anesthetized with pentobarbital sodium, 50 mg/kg i.p. and a jugular vein and femoral artery cannulated. Saline, arachidonic acid (1, 2, 4 or 6 mg/kg) alone or 15 minutes after administration of indomethacin (5 mg/kg), prostaglandin E2 (0.5, 1, 2 or 4 micrograms/kg) (PGE2), prostaglandin F2 alpha (20, 40, 80 or 160 micrograms/kg) (PGF2 alpha) or prostaglandin I2 (prostacyclin) (0.5, 1, 2 or 4 micrograms/kg) (PGI2) were given intravenously. Each of the drugs caused a dose-dependent decrease in blood pressure except for PGF2 alpha which caused an initial, short-lasting fall in blood pressure followed by a more sustained rise in blood pressure. The permeability of the blood-brain barrier was measured using 99mTc-sodium pertechnetate (TcO-4). None of the prostaglandins or arachidonic acid caused a significant change in the permeability of the blood-brain barrier. This provides a further example of a dissociation between drug-induced changes in systemic blood pressure and change in the permeability of the blood-brain barrier.