Effects of selective head cooling on brain cell membrane activity during postischemic reperfusion

To examine the effect of selective head cooling (SHC) on brain cell membrane activity involving ATPase, phospholipase A2, content of total membrane phospholipids during postischemic reperfusion, so as to elucidate the possible underlying mechanism on resuscitating effect of SHC.

Complete cerebral ischemia (CCI) was induced by the four-vessel model. 56 New Zealand rabbits were allocated randomly into two groups, non-ischemic control group had 30, 180 and 360 minutes reperfusion after CCI (n = 8); and SHC group with the same ischemic-reperfusion insult were all treated with SHC (28 degrees C, surface cooling method). Changes of Na+, K(+)-ATPase, Ca2+, Mg(2+)-ATPase, phospholipase A2, total phospholipids of brain cell membrane were observed. Comparison of data between two groups was made by Students' t test.

Compared with non-ischemic controls following 30 minutes CCI, activities of Na+, K(+)-ATPase stepwisely decreased at 30, 180 and 360 minutes, Ca2+, Mg(2+)-ATPase dropped at 180 and 360 minutes, phospholipidase A2 increased markedly at 30, 180, 360 minutes, and total phospholipids decreased at 180 and 360 minutes reperfusion (P < 0.01). Selective head cooling inhibited all the above changes significantly (P < 0.01).

The results suggest that selective head cooling initiated soon after reperfusion is beneficial for brain cell membrane function recruitment, which provides favourable effects on the damaged but still remediable brain cells for their resuscitation.