OBJECTIVETo study the modulation of neutrophil apoptosis and necrosis, elucidate the protecton mechanisms of dexamethasone.

METHODS50 rats were divided into 5 groups. I: normal island flap. II: artery occlusion for 8 hours, saline given into peritoneal. III: venous occlusion for 8 hours, saline given into peritoneal. IV: artery occlusion for 8 hours, dexamethasone injected through peritoneal. V: venous occlusion for 8 hours, dexamethasone injected through peritoneal. Flap survived areas were measured, neutrophil apoptosis and necrosis values were ananlyzed with FCM. Their morphology were observed with light microscopy. The swallows of apoptotic neutrophil by mascrophages were studied with transmission electron microscopy.

RESULTSFlap survived areas I, IV and V groups were higher than that in II and III groups, which in I, IV, V had no significant values. Apoptotic neutrophils values in II and III groups on 1, 3 days were less than that in, but on 6 days, higher than that in I, IV and V. Necrotic neutrophils showed another tendency postoperatively when compared with its apoptotic values. There were more swallows of apoptotic neutrophils in flaps of IV, V groups than that in II, III flaps.

CONCLUSIONDexamethasone's flap protection results from modulating of neutrophils apoptosis, decreasing it's necrosis, increasing swallowings values of apoptotic neutrophils by macrophages.