HYDROXYETHYL STARCH SOLUTION ATTENUATES BLOOD-BRAIN-BARRIER DISRUPTION CAUSED BY INTRACAROTID INJECTION OF HYPEROSMOLAR MANNITOL IN RATS

This study was performed to investigate whether a fraction of hydroxye thyl starch macromolecules, prepared from pentastarch and known as ''H ES-Pz'', with molecular weights of 100,000-1,000,000, protects against blood-brain barrier (BBB) disruption due to intracarotoid injection o f hyperosmolar mannitol. Rats were anesthetized with isoflurane, and r etrograde catherization of a unilateral external carotid artery was pe rformed. Except for the Control group (n = 8), hemodilution was perfor med using lactated Ringer's solution (LR group, n = 7), 6% hetastarch (HES group, N = 7), or 6% HES-Pz (HES-Pz group, n = 8) to reduce the h ematocrit to about 23%. The BBB transfer coefficient (K-i) of C-14-alp ha-aminoisobutyric acid was determined after a unilateral intracarotid injection of 25% mannitol. Blood pressure and hematocrit were similar in all groups. In the control group, K-i was increased significantly in the ipsilateral cortex (IC) where mannitol was injected (16.3 +/- 6 .1 vs 4.1 +/- 1.4 mu L . g(-1) min(-1)) when compared with the contral ateral cortex (CC). K-i was similar in the CC in all four groups. The K-i in the IC was significantly lower in the HES-Pz (6.4 +/- 3.5 mu L . g(-1) . min(-1)) than in the Control, HES, or LR group (16.3 +/- 6.1 , 19.0 +/- 12.9, 17.9 +/- 10.8 mu L . g(-1) . min(-1), respectively). Our data suggest that HES-Pz significantly attenuates disruption of th e BBB caused by an injection of hyperosmolar mannitol.