Porcine alveolar macrophage inducible nitric oxide synthase (inos): Analysis of mrna induction, protein expression, enzyme activity and nitric oxide production

Inducible NOS appears to play a major role in the defense mechanisms of rodent macrophages, in which its product (nitric oxide) serves as a potent antimicrobial agent. In macrophages, iNOS is induced by activation with Interferon-γ in conjunction with LPS. Reverse Transcription-PCR was used to study induction of iNOS mRNA in activated macrophages. Expression of iNOS was evaluated by western blotting and enzymatic activity. Nitric oxide, as nitrite, was determined with the Griess reagent. Stimulated porcine alveolar macrophages showed iNOS mRNA induction by RT-PCR; however, no enzyme activity or nitrite was detectable. The results suggest that, although iNOS RNA is induced in activated macrophages, the levels of enzymatic activity which are attained do not result in appreciable activity or product accumulation. Therefore, iNOS regulation in porcine macrophages appears to be similar to that observed in human macrophages.