IN-VITRO EFFECTS OF NITROGEN-DIOXIDE ON THE RELEASE OF NITRIC-OXIDE BY BOVINE ALVEOLAR MACROPHAGES

Bovine alveolar macrophages (BAM) were assessed for nitric oxide-produ ction after exposure to synthetic air or NO2 [0.2 ppm] for 2 h and sub sequent treatment with lipopolysaccharide (LPS) [1 mu g/ml]. Nitric ox ide (NO) release, measured as nitrite in the supernatant, was quantifi ed at different time points. LPS-stimulated BAM showed elevated nitrit e levels after 24 h. Pre-treatment with NO2 resulted in higher nitrite levels in comparison to air exposed BAM. Some of the BAM preparations resulted in pre-activated macrophages that produce high amounts of NO without LPS treatment. Within these cells LPS treatment reduced the n itrite levels in comparison to untreated control incubations from the same preparation. These pre-activated BAM exhibited no uniform effect after NO2-exposure. In some experiments nitrite levels of pre-activate d control BAM were decreased, while in others no influence could be ob served. NO-production by pre-activated BAM or after I,PS-treatment cou ld be inhibited by N-G-monomethyl-L-arginine (L-NMMA) [1 mM]. In order to investigate, whether NO2-exposure alters inducible NO-synthase mRN A expression, we now perform reverse transcription polymerase chain re action (RT-PCR) of iNOS mRNA. This method will be a good tool to eluci date whether NO2-exposure can modulate iNOS mRNA expression. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.