Early effects of exogenous arginine after the implantation of prosthetic material into the rat abdominal wall

We have investigated the effects of high arginine (Arg) levels (7.5 mg/100 g body weight per hour) on the early integration of biocompatible mesh graf ts into the rat abdominal wall. Studies were performed over implantation in tervals of 6, 12, 24 or 48 hours (n = 12, each). Arginine and related compo unds were quantified in plasma, wound fluids and multiple tissues. Plasma n itric oxide (NO) production was studied. Strips were taken from the polypro pylene fiber-host tissue interfaces (PTIs) for optical microscopic analysis and for immunohistochemical analysis using rat-specific antibodies against type I and type III collagens. Exogenous Arg was metabolized at the periph eral tissues but reliably reached the wound space. High amounts of Arg and ornithine (Orn) were detected in the specimens considered. No changes on ci trulline (Ctr) or NO concentrations were observed, overall suggesting that, during the period studied, the arginase pathway predominated. The acute sc arring response differed significantly in the two placements considered. Th e P-SS interface evidenced more extensive new tissue growth than the P-DS i nterface. Forty-eight hours after mesh implantation cellular infiltration, fibroblast proliferation, and mesh-surrounding angiogenesis were higher in the arginine-treated rats. Type III collagen staining was related to argini ne treatment, being higher (+ +) in the study group. In conclusion, and ind ependently of the site of mesh placement, supplemental Arg seemed to favora bly affect early local collagen deposition. This could be potentially helpf ul to ameliorate the integration of biomaterials into the tissues and, cons equently, to allow for the design of more selective therapeutic strategies to prevent hernia recurrence rates. (C) 2000 Elsevier Science Inc. All righ ts reserved.