Segment-selective absorption of lysozyme in the intestine.
Absorption of fluorescein isothiocyanate-labeled lysozyme (FITC-lysozyme) was examined in rat small intestine. Messenger RNA of megalin, an endocytic receptor for lysozyme in the kidney, was expressed in the lower but not in the upper intestine. In in situ closed loop and recirculation methods, absorption of FITC-lysozyme from the upper intestine was much higher than from the lower intestine. The absorption rate of FITC-lysozyme in the upper intestine was significantly higher than FITC-dextran and was inhibited by unlabeled lysozyme in a concentration-dependent manner. The absorption of FITC-lysozyme was also inhibited by spermine and phenylarsine oxide. These results indicate that the intestinal absorption of lysozyme is segment-selective and occurs preferentially from the upper intestine. Megalin expressed in the lower intestine appears not to have a significant role in the absorption of lysozyme. In the upper intestine, lysozyme appears to be absorbed by an endocytic pathway, and cationic charge may be important for lysozyme absorption.
Department of Pharmaceutics and Therapeutics, Programs for Pharmaceutical Sciences, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan. takanom@hiroshima-u.ac.jp
Mikihisa
M
Takano
Yuka
Y
Koyama
Hiromi
H
Nishikawa
Teruo
T
Murakami
Ryoko
R
Yumoto
D000818:Animals; D007408:Intestinal Absorption / Q000502:physiology*; D007421:Intestine, Small / Q000201:enzymology*; D008297:Male; D009113:Muramidase / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D009113:Muramidase