Reversible osmotic opening of the blood-brain barrier. Prevention of tissue damage with filtration of the perfusate.

Histological and fluoromicroscopical studies were performed in order to obtain information about reversibility and associated tissue damage of an osmotic opening of the blood-brain barrier. Three ml of 1.4 M mannitol solution were perfused through the right carotid artery of a rat, and the opening of the blood-brain barrier was examined by using EVans blue as a tracer. The barrier was opened for 60-120 minutes and then reestablished without gross neurological defect. Microscopically, however, edematous change and microinfarcts were often observed, which might be due to microembolism of recrystallized mannitol. With filtration of the perfusate through a millipore filter, the blood-brain barrier was reversibly opened without any tissue damages. This could be a useful therapeutic technique and an experimental model for neurotoxicology.