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

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. 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 5 micro 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. 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. 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

Effect of Nelumbo nucifera rhizome extract on the gastrointestinal tract of rat.

Extract of Nelumbo nucifera rhizome (RNN) was used as anti-diarrheal agent to combat the diarrhea in experimental rats. The RNN extract in graded doses (100, 200, 400 and 600 mg/kg body wt.) reduced not only the frequency of defecation, wetness of fecal dropping and PGE2 induced enteropooling but also the propulsive movements of charcoal meal significantly.

Characterization of nerve-induced relaxation of gastrointestinal sphincteric smooth muscle in a South American opossum (Didelphis albiventris)

The presence of inhibitory nonadrenergic noncholinergic (NANC) intrinsic innervation of the circular muscle of the gastrointestinal sphincters of the South American (SA) opossum was investigated in vitro. Isolated circular muscle strips from the esophagogastric and ileocolonic junctions but not from the gastroduodenal (pylorus) region developed spontaneous tension. Tetrodotoxin (TTX, 1 muM) augmented the spontaneous tension only in the ileocolonic junction strips. Electrical field stimulation of esophagogastric and ileocolonic junction strips caused frequency-dependent responses consisting of a relaxation at lower frequencies (<1 Hz) and a biphasic response or contraction at higher frequencies. In the strips from the pyloric region electrical field stimulation abolished the spontaneous activity at lower frequencies and induced contractions at higher frequencies. The responses elicited by electrical field stimulation in the three sphincters were abolished by TTX (1 muM). Electrical field-induced contractions were reduced while relaxations were enhanced by atropine (1 muM). In the presence of atropine (1 muM) and guanethidine (3 muM), electrical field stimulation, nicotine and ATP induced frequency-or concentration-dependent relaxations of the three sphincters that were abolished by TTX (1 muM). Isoproterenol and sodium nitroprusside caused concentration-dependent relaxations which were TTX-resistant. These findings indicate that the sphincteric circular muscle of the SA opossum gastrointestinal tract is relaxed by the activation of intrinsic NANC nerves and therefore can be used as a model for the study of the mechanisms involved in these responses.

effect of serotonin on basal gastric acid secretion in pylorus ligated rats of different age groups

The effect of serotonin on gastric acid secretion and its acidity have been examined by using four hour pylorus ligated rats of different age groups. Serotonin alone decreased the volume of gastric secretion and, free and total acidity in both younger and older animals, while methylsergide alone increased these parameters. Each of these drugs produced a significantly higher response in older animals. Methylsergide when given with serotonin abolished the inhibitory effect of serotonin and the observed secretions were similar to those of basal state. This indicates that serotonin as gastric inhibitor acts in accordance with parietal cell mass which increases with age

Evidence for the involvement of nitric oxide in the electrically induced relaxations of human lower esophageal sphincter and distal pylorus

The aim of the present study was to investigate in vitro the effect of Ng-nitro-L-arginine methyl ester (L-NAME), a nitric oxide (NO) synthase inhibitor, on neurogenic relaxation of human lower esophageal sphincter (LES) and distal pylorus (DP) circular muscle strips induced by electr4ical field stimulation (EFS). Muscle strips obtained from 5 patients who underwent total gastrectomy were suspended in 10-ml organ baths containing Krebs solution for recording isometric tension. L-NAME(30 uM) reduced the amplitude of the EFS-induced relaxation by 85 ñ 9% (N=3) in the LES and by 52 ñ 16% (N=3) in the DP but did not affect sodium nitroprusside-induced relaxation. L-Arginine (300 uM) partially reversed the L-NAME inhibition in the LES and totally in the DP. These findings suggest a role for L-arginine-derived NO in the nerve-mediated NANC relaxation of the human LES and DP