Transient blood-brain barrier permeability following profound temporary global ischaemia: an experimental study using 14C-AIB.

The influence of reperfusion after profound incomplete forebrain ischaemia on blood-brain barrier (BBB) permeability to a small protein tracer was studied in male Sprague-Dawley rats. The mean cortical blood to brain transfer constant (Ki) for 14C-amino isobutyric acid (AIB) was significantly greater at 3 and 6 h of reperfusion, 2.5 times the mean values of controls (p less than 0.05) (2.5 microliter g-1 min-1 and 1.0 microliters g-1 min-1 respectively), but had returned to control values after reperfusion for 24 h. Analysis of distribution of Ki values showed that following 15 min and 30 min of profound ischaemia, there was a significant increase in transfer of AIB across the blood-brain barrier (BBB) after recirculation for up to 6 h, though there was no evidence of protein extravasation as assessed by Evans Blue (EB) dye. After 24 h of reperfusion, the BBB to AIB was restored, and Ki values had returned to control values. It is concluded that following transient global ischaemia, the BBB may recover rapidly.