In the present study, we report that molecular and immunochemical techniques were unable to detect NOS-II mRNA or NOS-II antigen in the lung up to 25 mins after LPS administration, whereas NOS-III mRNA and NOS-III antigen were invariably detected in the lung of control and LPS-treated rats. Specific mRNA was screened for rat isoforms by reverse transcription polymerase chain reaction (RT-PCR) and confirmed by dot blot and Northern blot analyses. Only 30 mins after starting LPS infusion, NOS-II mRNA and NOS-II antigen appeared simultaneously. NOS-III and NOS-II mRNA were visualized by in situ hybridization technique with nonradioisotope polymerase chain reaction-(PCR) labelled specific cDNA probes, and NOS-III and NOS-II antigens were visualized by histochemical staining with commercial rabbit isoform-specific polyclonal antibodies. buy ortho tri-cyclen
Exogenous nitric oxide donor (S-nitro-N-acetyl-penicyl-lamine [SNAP]) prevented that effect. When a preferential NOS-II inhibitor 1-amino-2-hydroxy-guanidine (AGD) (15mg/kg intravenously) was used instead of L-NNA, there were no pneumotoxic effects of LPS.
We demonstrate that the immediate hypotensive phase of LPS action is associated with activation of NOS-III but not NOS-II in the lung. Moreover, nitric oxide generated in this way does not act as a vasodilator in peripheral circulation but counteracts the injury to pulmonary circulation that is locally inferred by toxic lipids released by LPS in the lung concomitantly.