A low dose of ionizing radiation increases luminal release of intestinal peptidases in rats.
OBJECTIVE
Mucosal inflammation in the small intestine is a potentially hazardous side effect of abdominal irradiation. In an effort to develop a quantitative method of evaluating mucosal damage, the luminal release of brush border enzymes in response to ionizing radiation was examined using two investigational strategies.


METHODS
First, a 20 cm segment of the proximal jejunum was perfused in situ and enzymatic activities within the perfusates were evaluated. In a second approach, enzymatic activities were directly evaluated in isolated brush border membranes from the jejunal mucosa.


RESULTS
Most of the peptidase activities measured were increased in the perfusates 1 day after irradiation and had returned to control levels at 4 days. In the brush border membranes, some enzyme activities decreased at 1 day and were, with the exception of leucineaminopeptidase (LAP), similar to control levels at 4 days.


CONCLUSIONS
LAP is more strongly affected by radiation than the transmembranously bounded enzymes.
Fittkau
M
M
Institute of Clinical Chemistry and Pathobiochemistry, Martin Luther University Halle-Wittenberg, Halle/Saale, Germany. marina.fittkau@medizin.uni-halle.de
Grothey
A
A
Gerlach
R
R
Schmoll
H J
HJ
D000818:Animals; D005260:Female; D007583:Jejunum / Q000201:enzymology* / Q000528:radiation effects* / Q000648:ultrastructure; D008871:Microvilli / Q000201:enzymology / Q000528:radiation effects; D010447:Peptide Hydrolases / Q000378:metabolism* / Q000528:radiation effects*; D011839:Radiation, Ionizing; D011879:Radiotherapy Dosage; D051381:Rats; D017208:Rats, Wistar
D010447:Peptide Hydrolases