Regulation of inducible nitric oxide synthase in post-operative adhesions

The deficiency of the inducible nitric oxide synthase (iNOS) substrate, L-arginine (L-Arg), the co-factor tetrahydrobiopterin (H4B) or molecular oxygen may lead to lower NO levels, which enhances the development of adhesion phenotype.

We utilized high-performance liquid chromatography (HPLC) and immunoprecipitation with nitrotyrosine antibody to determine the levels of H4B, citrulline and protein nitration in fibroblasts established from normal peritoneal and adhesion tissues.

The level of H4B was dramatically attenuated in adhesion fibroblasts. The immunoprecipitation with nitrotyrosine antibody revealed higher protein nitration in adhesion compared with normal fibroblasts. There were higher accumulations of citrulline in adhesion fibroblasts as compared with normal fibroblasts. In addition, peritoneal fibroblasts treated with 2% oxygen for 24 h and implanted back into the peritoneal cavity of the rats exhibited marked increase in severity of adhesion as well as extensive distribution involving many sites and organs.

Control of the catalytic activity of iNOS in adhesion fibroblasts may be because of subsaturating amounts of L-Arg and H4B which allow iNOS to generate a combination of reactive oxygen species in addition to NO, thereby influencing NO bioavailability and function.