Mechanisms involved in the augmentation of arachidonic acid-induced free-radical generation from rat neutrophils following hypoxia-reoxygenation

Polymorphonuclear leukocytes are known to play an important role in hypoxia /ischemia and reoxygenation injury. The present study was undertaken to inv estigate the involvement of protein kinase C, calmodulin, and cyclic adenos ine monophosphate in the augmentation of the free-radical generation observ ed after hypoxia-reoxygenation (H-R), Free-radical generation from the rat polymorphonuclear leukocytes was measured as the arachidonic acid (1-5x10(- 5) M)-induced luminol-dependent chemiluminescence response, which was augme nted following H-R. The increase in free-radical generation after H-R was c ompletely blocked by the pretreatment of cells with PKC inhibitor H-7, wher eas indomethacin (a cyclo-oxygenase inhibitor) or forskolin (an adenylate c yclase activator) failed to modulate the H-R-dependent response. However, W -7-a calcium/calmodulin (Ca2+/CaM) antagonist-partially reduced the augment ed free-radical generation observed in the H-R cells. Results obtained thus suggest the possible involvement of protein kinase C and calcium in the au gmentation of the free-radical generation response following H-R. (C) 2000 Elsevier Science Ltd. All rights reserved.