High concentrations of histamine stimulate equine polymorphonuclear neutrophils to produce reactive oxygen species.
OBJECTIVE
Because high concentrations of histamine are locally released in inflammation, we investigated the effects of supraphysiological doses of histamine on the production of reactive oxygen species (ROS) by neutrophils.


METHODS
Isolated equine neutrophils were activated by 10(-4) to 5 x 10(-3) M histamine. The production of ROS and free radicals was estimated by luminol-enhanced chemiluminescence (CL) and electron spin resonance (ESR) with spin trapping technique. In this model of histamine-stimulated neutrophils, we tested the antagonists of H1 and H2 histamine receptors, the role of Ca2+ and Mg2+, the role of staurosporine and pertussis toxin (inhibitors of protein kinase C and proteins G) and the effects of superoxide dismutase, catalase, hydroxyl radical scavengers (phenylalanine and mannitol) and N(G)-monomethyl-L-arginine (L-NMMA), inhibitor of NO-synthase.


RESULTS
Histamine (from 10(-5) to 10(-3) M) stimulated neutrophils to produce CL and ESR signals characterized by spin adducts of superoxide anion and/or hydroxyl radicals. The CL response was inhibited by 10(-4) and 10(-3) M H1 receptor antagonists (promethazine, pyrilamine, and diphenhydramine), by Ca2+ and Mg2+ depletion and by 10 nmoles staurosporine. CL was partially inhibited by pertussis toxin (4 microg/ mL). The ESR signals were practically suppressed by pyrilamine (an H1 receptor antagonist) and superoxide dismutase, and partially inhibited by catalase, hydroxyl radical scavengers and L-NMMA (respectively 59, +/- 30% and 68% inhibition).


CONCLUSIONS
High concentrations of histamine stimulated the neutrophils to product ROS and free radicals via H1 receptors and the NADPH-oxidase pathway.
Benbarek
H
H
Anesthésiologie Générale et Pathologie Chirurgicale des Grands Animaux, Faculté de Médecine Vétérinaire, B44, Université de Liège, Domaine Universitaire du Sart Tilman, Belgique.
Mouithys-Mickalad
A
A
Deby-Dupont
G
G
Deby
C
C
Grülke
S
S
Nemmar
A
A
Lamy
M
M
Serteyn
D
D
D000818:Animals; D002118:Calcium / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005609:Free Radicals / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism; D006632:Histamine / Q000494:pharmacology*; D006736:Horses / Q000378:metabolism*; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D008163:Luminescent Measurements; D008274:Magnesium / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D011968:Receptors, Histamine / Q000187:drug effects / Q000378:metabolism; D013268:Stimulation, Chemical
D004791:Enzyme Inhibitors; D005609:Free Radicals; D007202:Indicators and Reagents; D017382:Reactive Oxygen Species; D011968:Receptors, Histamine; D006632:Histamine; D009247:NADH, NADPH Oxidoreductases; D011493:Protein Kinase C; D019204:GTP-Binding Proteins; D008274:Magnesium; D002118:Calcium