the effect of n-nitro-l-arginine methyl ester (l-name) on the thickness and number of circular smooth muscle cells of pylor in rat embryo

introduction: the aim of this study is to investigate the effect of one nitric oxide inhibitor on the thickness and number of circular smooth muscle cells of pylor in rat embryo. material and methods: to determine the influence of nitric oxide reduction on the muscular layer of pylor in rat embryo, in the present study, pregnant sprague-dawley rats received the no synthase inhibitor n-nitro-l-arginine methyl ester (l-name). a dose of 80mg/kg of l-name solution in saline was injected to the rats intraperitoneally (ip) during the middle week and last week of the pregnancy period per day. the embryos were removed on the expected day of delivery. their stomach and duodenum were dissected, fixed by bouin solution and tissue processing was carried out. by using a rotary microtome 5µ serial cross sections were obtained and stained with trichrom-mason and pop-nicola. then sections were evaluated for thickness and number of circular smooth muscle cells under a light microscope using a scaled lens and a checkered lens eye-piece. results: statistical analysis (one-way anova- duncan)of light microscopic findings indicated that 80mg/kg of l-name in the last week of pregnancy (the first trial group) results in pyloric hypertrophy and hyperplasia. conclusion: on the basis of these results we believe that reductions of nitric oxide production in the third trimester of pregnancy could be one of the reasons of pyloric stenosis in infants.