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标题：Nonlinear Intestinal Absorption of (1→3)-β-D-Glucan Caused by Absorptive and Secretory Transporting System
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作者：Mikio Tomita ; Mitsutaka Miwa ; Shohei Ouchi 等
期刊名称：Biological and Pharmaceutical Bulletin
印刷版ISSN：0918-6158
电子版ISSN：1347-5215
出版年度：2009
卷号：32
期号：7
页码：1295-1297
DOI：10.1248/bpb.32.1295
出版社：The Pharmaceutical Society of Japan
摘要：The mechanism of the nonlinear concentration dependence of intestinal absorption of (1→3)-β- D -glucan was studied using in situ rat intestinal perfusion, as well as the in vitro Ussing-type chamber method mounted with rat intestinal tissue. The intestinal absorption rate constant of a (1→3)-β- D -glucan, laminaran, evaluated by the loop method increased significantly with increasing concentration of laminaran up to 0.5 μ M in a nonlinear fashion and tended to decrease at higher concentrations. Mucosal-to-serosal directed permeation of the laminaran across rat ileal sheets evaluated by the in vitro Ussing-type chamber method also decreased in a dose-dependent fashion. Serosal-to-mucosal directed permeation decreased in a concentration-dependent manner. In addition, the serosal-to-mucosal flux was reduced in the presence of metabolic inhibitor, 2,4-di-nitrophenol. These results suggest that laminaran is secreted into the intestinal lumen predominantly by the efflux transporting system. We conclude that intestinal transport of (1→3)-β- D -glucan involves specialized transporter or something similar in both absorptive and secretory directions, and complex nonlinear intestinal absorption characteristics can be ascribed to the participation of multiple transport mechanism.
关键词：(1→3)-β- D -glucan;laminaran;nonlinear absorptive transport;nonlinear secretory transport;rat intestine