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Ewert S, Johansson B, Holm M, Helander HF, Fandriks L: The bradykinin BK2 receptor mediates angiotensin II receptor type 2 stimulated rat duodenal mucosal alkaline secretion. BMC Physiol. 2003 Feb 22;3:1. Epub 2003 Feb 22. BACKGROUND: This study investigates bradykinin and nitric oxide as potential mediators of AT2-receptor-stimulated duodenal mucosal alkaline secretion. Duodenal mucosal alkaline secretion was measured in methohexital- and alpha-chloralose-anaesthetised rats by means of in situ pH-stat titration. Immunohistochemistry and Western blot were used to identify the BK2 receptors. RESULTS: The AT2 receptor agonist CGP42112A (0.1 microg kg (-1) min (-1)) administered intravenously increased the duodenal mucosal alkaline secretion by approximately 50 %. This increase was sensitive to the selective BK2 receptor blocker HOE140 (100 ng/kg i.v.), but not to luminal administration of the NOS blocker L-NAME (0.3 mM). Mean arterial pressure did not differ between groups during the procedures. Immunohistochemistry showed a distinct staining of the crypt epithelium and a moderate staining of basal cytoplasm in villus enterocytes. CONCLUSION: The results suggest that the AT2-receptor-stimulated alkaline secretion is mediated via BK2 receptors located in the duodenal cryptal mucosal epithelium. |
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