S-nitrosothiols are stored by platelets and released during platelet-neutrophil interactions.
Interaction between platelets and neutrophils is important in vascular injury. We have investigated the storage and release of nitric oxide (NO) by platelets interacting with neutrophils. Shear-activated platelets were added to neutrophils in suspension and both superoxide and peroxynitrite formations monitored by lucigenin- and luminol-enhanced chemiluminescence. In addition, intraplatelet S-nitrosothiols were measured by dichlorofluorescein fluorescence following displacement of NO by mercuric chloride. Addition of activated platelets to neutrophils caused free radical production and platelet-neutrophil rosette formation. Pretreatment of platelets with 20 microM S-nitrosoglutathione changed the balance between luminol and lucigenin chemiluminescence in favor of luminol, whereas S-nitrosoglutathione in platelet-free plasma did not produce these changes. This pattern was also observed both following inhibition of neutrophil NO synthase and in a neutrophil-free superoxide-generating system. Inhibition of platelet NO synthase decreased luminol and increased lucigenin chemiluminescence. These effects were reversed by L-arginine. Platelet activation increased intraplatelet S-nitrosothiols from 1.93+/-0.19 (mean +/- SD) to 4.9+/-1.10 x 10(-18) mol/platelet (P < 0.01); this increase halved following NO synthase inhibition, but was enhanced by approximately 220% following incubation with S-nitrosoglutathione. These results show that during shear stress platelets store S-nitrosothiols, which can be derived either endogenously from NO synthesis or exogenously by sequestration of S-nitrosoglutathione. Release of stored NO during platelet-neutrophil interaction alters the interaction of NO with superoxide and could modulate vascular inflammation.
Hirayama
A
A
Department of Medicine, University College London, United Kingdom.
Noronha-Dutra
A A
AA
Gordge
M P
MP
Neild
G H
GH
Hothersall
J S
JS
D001119:Arginase / Q000494:pharmacology; D001792:Blood Platelets / Q000166:cytology / Q000378:metabolism*; D002448:Cell Adhesion; D005978:Glutathione / Q000031:analogs & derivatives* / Q000097:blood; D006801:Humans; D066298:In Vitro Techniques; D018375:Neutrophil Activation / Q000187:drug effects; D009504:Neutrophils / Q000166:cytology*; D009566:Nitrates / Q000494:pharmacology; D009569:Nitric Oxide / Q000097:blood; D009603:Nitroso Compounds / Q000097:blood*; D026422:S-Nitrosoglutathione; D013481:Superoxides / Q000097:blood; D014969:Xanthine Oxidase / Q000494:pharmacology
D009566:Nitrates; D009603:Nitroso Compounds; D013481:Superoxides; C039642:peroxynitric acid; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D014969:Xanthine Oxidase; D001119:Arginase; D005978:Glutathione