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 investigate the involvement of protein kinase C, calmodulin, and cyclic adenosine monophosphate in the augmentation of the free-radical generation observed 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 augmented following H-R. The increase in free-radical generation after H-R was completely blocked by the pretreatment of cells with PKC inhibitor H(7), whereas indomethacin (a cyclo-oxygenase inhibitor) or forskolin (an adenylate cyclase activator) failed to modulate the H-R-dependent response. However, W(7)-a calcium/calmodulin (Ca(2+)/CaM) antagonist-partially reduced the augmented free-radical generation observed in the H-R cells. Results obtained thus suggest the possible involvement of protein kinase C and calcium in the augmentation of the free-radical generation response following H-R.
Sethi
S
S
Department of Pharmacology, Central Drug Research Institute, Lucknow, India.
Singh
M P
MP
Dikshit
M
M
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology*; D002147:Calmodulin / Q000494:pharmacology; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D005609:Free Radicals / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism*; D008163:Luminescent Measurements; D008297:Male; D009504:Neutrophils / Q000378:metabolism*; D010084:Oxidation-Reduction; D011493:Protein Kinase C / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D015290:Second Messenger Systems / Q000502:physiology
D002147:Calmodulin; D016861:Cyclooxygenase Inhibitors; D005609:Free Radicals; D017382:Reactive Oxygen Species; D016718:Arachidonic Acid; D011493:Protein Kinase C; D000262:Adenylyl Cyclases