Role of nitric oxide in apoptosis of human peritoneal and adhesion fibroblasts after hypoxia

To study the modulation of the inducible nitric oxide synthase/nitric oxide (iNOS/NO) expression system in fibroblasts isolated from human peritoneum and adhesion tissues by hypoxia. Prospective experimental study. University medical center. Cultures of fibroblasts from both peritoneum and adhesion tissues of five patients. Hypoxia treatment of the primary cultured fibroblasts. We used Western and Northern blots to determine whether iNOS mRNA and its protein were present in peritoneal and adhesion fibroblasts and whether this expression is modulated by hypoxia. Multiplex reverse transcription polymerase chain reaction (RT-PCR) technique was used to quantify type I collagen mRNA in response to N ^G-nitro-L-arginine methyl ester (L-NAME). A terminal deoxynucleotidyl transferase mediated dUTP nick-end-labeling (TUNEL) assay was used to quantify apoptosis in response to NO donor S-nitro-N-acetyl- penicillamine (SNAP) treatment. A Griess assay was used to measure NO levels. Peritoneal fibroblasts have significantly higher NO levels than adhesion fibroblasts. Hypoxia decreased NO in peritoneal fibroblasts to levels observed for adhesion fibroblasts. In addition, hypoxia increased both mRNA and protein levels of the iNOS gene in peritoneal and adhesion fibroblasts. Augmentation of NO by SNAP treatment increased apoptosis in adhesion fibroblasts. In contrast, SNAP had no effect on apoptosis of peritoneal fibroblasts. Inhibition of NO by L-NAME treatment increased type I collagen mRNA levels in peritoneal fibroblasts. Our findings confirm that adhesion fibroblasts produce less NO than normal peritoneal fibroblasts; NO may be the mechanism responsible for the creation and persistence of the adhesion phenotype.