EXPOSURE TO IONIZING RADIATION ALTERS MUCOSAL VASOREACTIVITY IN RATJEJUNUM EX VIVO

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Authors
  1. MacNaughton, W.K.
  2. Leach, K.
  3. Prud'homme-Lalonde, L.
Corporate Authors
Defence Research Establishment Ottawa, Ottawa ONT (CAN)
Abstract
The effect of ionizing radiation on jejunal mucosal blood flow was investigated in rats receiving whole body exposure to 10 Gy gamma -radiation. Irradiation resulted in increased myeloperoxidase activity, indicative of neutrophil infiltration, and prostaglandin E2 synthesis by 2 hr post-irradiation, but had no effect on leukotriene B4 synthesis. In ex vivo intestinal chamber studies, exposure to radiation reversed the mucosal blood flow changes elicited by intravenous administration of leukotriene C4 (1 mu m g/kg/min for 10 min) or endothelin-1 (1 mu m g/kg/min for 5 min), but not those elicited by topical capsaicin (100 or 640 mu m M) as measured by laser Doppler flowmetry. The effect of radiation on vascular responses to leukotriene C4, but not those to endothelin-1, was reversed by pretreatment of the rats with the cyclo-oxygenase inhibitor, indomethacin (5 mg/kg). There was no significant effect of irradiation on mean arterial pressure or on ion or protein effluxes into the chamber bathing solution, nor did irradiation alter transmural potential difference. These studies point to altered responsiveness of the jejunal mucosal vasculature shortly after exposure to ionizing radiation. Changes in function could reflect the onset of an acute inflammatory response, and appear to have cyclo-oxygenase-dependent and independent components.
Keywords
Radiation-induced diarrhea;Vasoreactivity
Report Number
DREO-TN-94-12 — Technical Note
Date of publication
01 Oct 1994
Number of Pages
23
DSTKIM No
95-00911
CANDIS No
149429
Format(s):
Hardcopy;Document Image stored on Optical Disk

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