Biomechanical properties of ileum after systemic treatment with epithelial growth factor.
OBJECTIVE
Systemic treatment with epidermal growth factor (EGF) leads to growth of all parts of the small intestine in normal functioning rats. In this study, we investigated the effect of this growth process on morphometric and biomechanical parameters of ileum.


METHODS
Rats were treated with EGF (150 microg.kg(-1)day(-1))or placebo via osmotic minipumps for 2, 4, 7, and 14 days. A segment of ileum was removed. The morphology at no-load state and zero-stress state was measured and passive biomechanical properties were assessed using a biaxial test machine (combined inflation and axial stretching).


RESULTS
The ileum weight increased after EGF administration. After 4 days' EGF treatment, the wall thickness was increased. Significantly smaller inner perimeters were seen in 4 day and 7 day EGF treatment groups. The opening angle and residual strain began to increase after 7 days' EGF treatment. Wall stiffness, evaluated from the stress-strain curves, showed a continuous decrease in circumferential direction during the first 7 days' EGF treatment. The longitudinal stiffness increased during the first 7 days. The stress-strain curves for both circumferential and longitudinal direction tended to shift back to normal 14 days after starting EGF administration.


CONCLUSIONS
EGF can cause significant changes both in the morphology and in the passive mechanical properties of the rat ileum.
Yang
Jian
J
Biomedical Engineering Center, Beijing Polytechnic University, China.
Zhao
Jing-Bo
JB
Zeng
Yan-Jun
YJ
Gregersen
Hans
H
D000818:Animals; D001696:Biomechanical Phenomena; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005260:Female; D007082:Ileum / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology*; D008954:Models, Biological; D009929:Organ Size; D051381:Rats; D017208:Rats, Wistar; D013314:Stress, Mechanical
D004815:Epidermal Growth Factor