Inhibition of eosinophil chemotaxis by chronic blockade of nitric oxide biosynthesis.
The effect of chronic N omega-nitro-L-arginine methyl ester (L-NAME) treatment on the in vivo eosinophil migration induced by bradykinin, platelet-activating factor (PAF), lipopolysaccharide and carrageenin has been investigated in the rat using the pleurisy model. The in vitro (microchemotaxis chamber) eosinophil migration induced by N-formyl-methionyl-leucyl-phenylalanine (fMLP), PAF and zymosan-activated serum was also evaluated in the rat. The eosinophils were obtained from the peritoneal cavity of male Wistar rats and isolated on a discontinuous metrizamide gradient. Chronic inhibition of nitric oxide biosynthesis was achieved by adding L-NAME to the drinking water to give an intake of approximately 75 mumol/rat/day for 4 weeks. Rats treated chronically with L-NAME developed a significant level of hypertension (163 +/- 4.8 mmHg; P < 0.01) compared with animals which received either the same dose of the inactive enantiomer D-NAME (124 +/- 3.2 mmHg) or tap water alone (119 +/- 1.6 mmHg). The intrapleural injection of bradykinin (50 micrograms), PAF (1 microgram), lipopolysaccharide (0.25 microgram) and carrageenin (125 micrograms) into untreated rats in vivo induced a significant level of eosinophil migration by 24 h post-injection. This migration was markedly reduced in L-NAME-treated rats. Eosinophils obtained from untreated rats showed a significant level of migration in vitro in response to fMLP (5 X 10(-8) M), PAF (10(-8) M) and zymosan-activated serum (27 microliters). In contrast, the migration induced by these chemotactic agents was markedly reduced in cells isolated from animals treated chronically with L-NAME. L-Arginine (5.5 mM), but not D-arginine (5.5 mM), restored the ability of eosinophils from L-NAME-treated animals to migrate in response to fMLP. Our results indicate that nitric oxide plays a major role in the in vivo and ex vivo migration of eosinophils.
Ferreira
H H
HH
Department of Pharmacology, Faculty of Medical Sciences, UNICAMP, Campinas, Brazil.
Medeiros
M V
MV
Lima
C S
CS
Flores
C A
CA
Sannomiya
P
P
Autunes
E
E
De Nucci
G
G
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002351:Carrageenan / Q000494:pharmacology; D002634:Chemotaxis, Leukocyte / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007958:Leukocyte Count; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D009569:Nitric Oxide / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D010972:Platelet Activating Factor / Q000494:pharmacology; D010994:Pleura / Q000166:cytology; D051381:Rats; D017208:Rats, Wistar
D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D010972:Platelet Activating Factor; D009569:Nitric Oxide; D009240:N-Formylmethionine Leucyl-Phenylalanine; D002351:Carrageenan; D001920:Bradykinin; D019331:NG-Nitroarginine Methyl Ester