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- Atuma, C, et al.
(författare)
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Helicobacter pylori extracts reduce gastric mucosal blood flow by a nitric oxide-independent but mast cell- and platelet-activating factor receptor-dependent pathway in rats
- 1999
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 34:12, s. 1183-1189
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: We have previously shown that water extracts from Helicobacter pylori reduce gastric mucosal blood flow by approximately 15%. It has also been suggested that H. pylori can inhibit endogenous nitric oxide (NO) biosynthesis. Our aim was to examine whether the reduction in blood flow induced by H. pylori is the direct consequence of an NO synthase inhibition and the possible involvement of mast cell degranulation.METHODS: A water extract was produced from wildtype strain 88-23. The extract was applied on the exteriorized gastric corporal mucosa in inactin-anesthetized rats, after removing as much as possible of the mucus layer, during intravital microscopy. Blood flow was measured with laser-Doppler flowmetry.RESULTS: In rats pretreated with the NO synthase inhibitor N-nitro-L-arginine there was a 19% +/- 6% reduction in blood flow 40 min after application of the extract, and a 27% +/- 9% reduction after another 20 min with saline. The reduction was abolished by concomitant pretreatment with the mast cell stabilizer ketotifen or the platelet-activating factor (PAF) receptor antagonist WEB2086.CONCLUSION: The reduction in mucosal blood flow induced by the extract was probably mediated through an acute inflammatory response involving mast cell degranulation with consequent PAF secretion. The effect on blood flow was not the result of a decrease in vascular tone due to an inhibition of endogenous NO biosynthesis.
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- Atuma, C, et al.
(författare)
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The adherent gastrointestinal mucus gel layer : thickness and physicalstate in vivo
- 2001
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Ingår i: American Journal of Physiology - Gastrointestinal and Liver Physiology. - 0193-1857 .- 1522-1547. ; 280, s. G922-G929
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Tidskriftsartikel (refereegranskat)abstract
- Divergent results from in vitro studies on the thickness and appearance of the gastrointestinal mucus layer have previously been reported. With an in vivo model, we studied mucus gel thickness over time from stomach to colon. The gastrointestinal tissues of Inactin-anesthetized rats were mounted luminal side up for intravital microscopy. Mucus thickness was measured with a micropipette before and after mucus removal by suction. The mucus layer was translucent and continuous; it was thickest in the colon (∼830 μm) and thinnest in the jejunum (∼123 μm). On mucus removal, a continuous, firmly adherent mucus layer remained attached to the epithelial surface in the corpus (∼80 μm), antrum (∼154 μm), and colon (∼116 μm). In the small intestine, this layer was very thin (∼20 μm) or absent. After mucus removal, there was a continuous increase in mucus thickness with the highest rate in the colon and the lowest rate in the stomach. In conclusion, the adherent gastrointestinal mucus gel in vivo is continuous and can be divided into two layers: a loosely adherent layer removable by suction and a layer firmly attached to the mucosa.
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