[A new experimental model for inducing interstitial cystitis by oxidative stress using bladder instillation of a nitric oxide donor gel]. / Un nuevo modelo experimental de inducción de cistitis intersticial mediante estrés oxidativo empleando instilación vesical de un gel donante de óxido nítrico.

PURPOSE: The aim of this study is to develop a new experimental model of inducing interstitial cystitis (IC) through vesical instillation of a polymeric solution containing the NO donor S-nitrousglutathione (GSNO) and to compare it to the experimental interstitial cystitis induced by vesical instillation of protamine and potassium chloride. MATERIAL AND METHOD: For that purpose 40 female Wistar rats were used, divided in four groups: 1. saline solution + GSNO; 2. saline solution + polymeric solution (without GNSO); 3. protamine sulphate + KCl; 4. protamine sulphate + GSNO. The rats received one application (5 animals) or 3 applications (5 animals) of the corresponding substance through intravesical instillation, and after 6 days (5 animals) or 9 days (5 animals) they were euthanized and their bladders were removed for macroscopic evaluation and histological study. RESULTS: In the macroscopic evaluation we observed edema and hyperemia of the mucosa in 2 (22%) of the animals in group 1, in 0 (0%) of the animals in group 2, in 10 (100%) of the animals in group 3, and in 5 (50%) of the animals in group 4. In the protamine + KCl group and in saline + GSNO similar effects were observed on the bladder wall. The animals in group 2 (saline + polymeric) showed vascular congestion, significantly smaller than the rest after 9 days instillations (p=0.0035). Significant increased fibrosis was observed after instillations in groups 3 and 4, after 6 days (p=0.3781) and 9 days (p=0.0459) respectively, when compared to control (group 2). All groups presented neutrophilic infiltrate of variable intensity 6 days after instillations (p=0.7277). After 9 days, there was a regression of the infiltrate, with no evidence of accentuated neutrophilic reaction in all the groups (p=0.2301). CONCLUSION: The inflammatory response to bladder instillation of an aqueous solution of S-nitrousglutathione was very similar to that induced by bladder instillation of protamine and KCl. Instillation of an aqueous solution of GSNO can be considered a new model for experimental induction of interstitial cystitis.