Changes of nitric oxide synthase and nitric oxide in lung of smoking rats

AIM: To observe the changes of iNOS and eNOS in lung tissue and NO in bronchoalveolar lavage fluid (BALF) in smoking rats. METHODS: 80 Wistar rats were divided into control, smoking group, L-NIL group and L-NAME group (rats were exposed to smoke and injected (i.p.) with selective iNOS inhibitor L-NIL or NOS inhibitor L-NAME). iNOS and eNOS protein levels in whole lung were detected by immunohistochemical staining, and NOS mRNA was quantified using RT-PCR. In addition, NO - 2/NO - 3 was determined using Griess assay. RESULTS: The expression of iNOS mRNA and protein in smoking rats increased, the expression of eNOS mRNA and eNOS protein decreased, and the total cell count and the level of NO - 2/NO - 3in BALF increased( P 0.05). In vivo , L-NIL reduced the total cell count and NO - 2/NO - 3 in BALF ( P 0.05), while L-NAME had no effect on them. CONCLUSION: Cigarette smoke increased expression of iNOS mRNA and protein and decreased expression of eNOS mRNA and protein. The large amount of NO generated by iNOS may amplify inflammation in lung tissue.