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Query: UMLS:C0003129 (Anoxia)
 551 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A vibration technique was used to dislocate the epithelium from the rat small intestine, in order to study the possible regulatory role of the epithelium on intestinal motility. Complete removal of the epithelium led to a slightly potentiated contraction of the longitudinal smooth muscle by the muscarinic agonist methacholine (pD2. 6.5 +/- 0.1 vs. 6.2 +/- 0.2). The maximal beta-adrenergic response expressed relative to the relaxation by 0.5 mM dibutyryl cyclic AMP increased from 55.9 +/- 9.0% to 72.6 +/- 9.1% by this treatment. Efforts were made to relate these observations to the endothelium-dependent relaxation in blood vessels, but no indication was found for a similar mechanism in the small intestine. Not only mechanical dislocation can be employed to affect the mucosal layer, but also intestinal ischemia has been reported to lead to mucosal damage. In this study we mimicked ischemia by applying in vitro anoxia and subsequent reoxygenation to isolated intestinal segments. When intestinal segments are isolated and kept in physiological buffer, xanthine dehydrogenase is converted slowly to xanthine oxidase, irrespective of whether the buffer is oxygenated or not. No evidence was found for oxygen radical damage after anoxia and reoxygenation. However, the intestinal mucosa was damaged both after normoxia, and after anoxia and reoxygenation. Anoxia and subsequent reoxygenation did not affect muscarinic contraction, but slightly increased the beta-adrenergic relaxation, which partly correlates with the effects of mechanical dislocation of the epithelium. The increased sensitivity of the smooth muscle after epithelial damage might be involved in motility changes during intestinal inflammatory diseases.
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PMID:Role of the epithelium in the control of intestinal motility: implications for intestinal damage after anoxia and reoxygenation. 141 84

The effects of anoxic submergence (20 h at 5 degrees C) and subsequent 24 h aerobic recovery on the antioxidant systems of six organs were examined in freshwater turtles, Trachemys scripta elegans. Both xanthine oxidase and xanthine dehydrogenase were detected in turtle tissues with xanthine oxidase composing 36-75% of the total activity. Turtle organs displayed high constitutive activities of catalase (CAT), superoxide dismutase (SOD), and alkyl hydroperoxide reductase (AHR). Measurements of lipid peroxidation damage products (conjugated dienes, lipid hydroperoxides, thiobarbituric acid reactive substances) showed minimal changes during anoxia or recovery suggesting that natural anoxic-aerobic transitions occur without the free radical damage that is seen during ischemia-reperfusion in mammals. Anoxia exposure led to selected decreases in enzyme activities in organs, consistent with a reduced potential for oxidative damage during anoxia: SOD decreased in liver by 30%, CAT decreased in heart by 31%, CAT and total glutathione peroxidase (GPOX) decreased in kidney (by 68 and 41%), and CAT and SOD decreased in brain (by 80 and 15%). AHR, however, increased 2 and 3.5 fold during anoxia in heart and kidney respectively. Most anoxia-induced changes were reversed during aerobic recovery although brain enzyme activities remained suppressed. Some specific changes occurred during the recovery period: SOD increased from controls in heart by 45%, AHR increased to 200 and 168% of control values in red and white muscle respectively, and total GPOX decreased from controls in heart and white muscle by 75 and 77% respectively. The results show that biochemical adaptation for natural anoxia tolerance in turtles includes well-developed antioxidant defenses that minimize or prevent damage by reactive oxygen species during the reoxygenation of organs after anoxic submergence.
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PMID:Antioxidant systems and anoxia tolerance in a freshwater turtle Trachemys scripta elegans. 914 33