RESUMO
Objective To investigate if isoflurane pretreatment can protect brain from bilateral hemispheric ischemia-reperfusion injury. Methods Seventy-eight male Wistar rats weighing 250-300 g were randomly divided into 4 groups : (A) sham operation group ( n = 15 ); (B) ischemia-reperfusion group (I/R, n = 21); (C) ischemia-preconditioning group (IP, n = 21) and (D) isoflurane pretreatment group (ISO, n = 21) Group B, C and D were further divided into 3 subgroups according to the duration of reperfusion 6 h, 24 h, 72 h. Global cerebral ischemia was produced by 4-artery occlusion technique. In sham operation group (A) bilateral vertebral and common carotid arteries were exposed but not occluded. In ischemia-reperfusion group (I/R) bilateral vertebral arteries were occluded by cauterization and bilateral common carotid arteries were exposed and clamped for 20 min, then undamped for reperfusion of different duration (6 h, 24 h and 72 h) . In ischemia-preconditioning group (C) ischemia-reperfusion was preceded by 3 min global ischemia. In isoflurane-pretreatment group (D) the animals inhaled 1,5% isoflurane for 2 h before I/R. The animals were sacrificed right after reperfusion and brain was removed immediately for microscopic examination of hippocampal CA1. The number of living neurons (HE staining) and apoptotic neurons (TUNEL) was counted. Results (1) In group B (I/R) the number of living neurons in CA1 was decreasing with duration of reperfusion from 90.2 ? 2.4 (after 6 h reperfusion) to 45.8 ??4.9 (72 h of reperfusion) ( P