title: Nitric oxide inhibits neutrophil beta 2 integrin function by inhibiting membrane-associated cyclic GMP synthesis.
abstract: The aim of this investigation was to identify the mechanism by which nitric oxide inhibits neutrophil beta 2 integrin dependent adherence. Isolated rat neutrophils from blood and peritoneal exudates were exposed for 2 min to nitric oxide generated by diethylamine-NO at rates between 1.6 and 138 nmol/min. Exposure to nitric oxide at rates less than 14 nmol/min had no effect on adherence. Exposure to 14 to 56 nmol nitric oxide/min inhibited beta 2 integrin dependent adherence to endothelial cells, nylon columns, and fibrinogen-coated plates, but higher concentrations had no significant effect on adherence. Adherence by beta 2 integrins could be restored by incubating cells with dithioerythritol, phorbol 12-myristate 13-acetate, or 8-bromo cyclic GMP. Elevations in cellular cyclic GMP concentration were associated with adherence, but this did not occur after cells were exposed to concentrations of nitric oxide that inhibited beta 2 integrin-dependent adherence. Elevations in cyclic GMP did occur after cells were incubated with dithioerythritol or phorbol 12-myristate 13-acetate. Concentrations of nitric oxide that inhibited beta 2 integrin-dependent adherence also inhibited catalytic activity of membrane associated guanylate cyclase and binding of atrial natriuretic peptide, but were insufficient to activate cytosolic guanylate cyclase. Nitric oxide did not inhibit neutrophil oxidative burst or degranulation, nor effect beta 2 integrin expression or adherence that did not depend on beta 2 integrins, nor cause oxidative stress identified in terms of cellular glutathione concentration or protein nitrotyrosine. The results indicate that nitric oxide inhibited beta 2 integrins in a concentration-dependent fashion by inhibiting cell-surface transduction of signals linked to the activity of membrane-bound guanylate cyclase. The inhibitory effect could be overcome by providing cells with cyclic GMP exogenously or by stimulating cytosolic guanylate cyclase.
authors.affiliation: Institute for Environmental Medicine, University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: P D
authors.initials: PD
authors.lastname: Banick
authors.forename: Q
authors.initials: Q
authors.lastname: Chen
authors.forename: Y A
authors.initials: YA
authors.lastname: Xu
authors.forename: S R
authors.initials: SR
authors.lastname: Thom
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism; D018821:CD18 Antigens / Q000502:physiology*; D002448:Cell Adhesion / Q000187:drug effects; D015550:Cell Degranulation; D006152:Cyclic GMP / Q000096:biosynthesis*; D005978:Glutathione / Q000378:metabolism; D006162:Guanylate Cyclase / Q000378:metabolism; D006834:Hydrazines / Q000494:pharmacology; D008297:Male; D009504:Neutrophils / Q000502:physiology*; D009569:Nitric Oxide / Q000494:pharmacology*; D009589:Nitrogen Oxides; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D016897:Respiratory Burst; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D018821:CD18 Antigens; D006834:Hydrazines; D009589:Nitrogen Oxides; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D009320:Atrial Natriuretic Factor; C084012:1,1-diethyl-2-hydroxy-2-nitrosohydrazine; D011493:Protein Kinase C; D006162:Guanylate Cyclase; D005978:Glutathione; D006152:Cyclic GMP; D013755:Tetradecanoylphorbol Acetate