Pharmacology & Pharmacy

Volume 2, Issue 3 (July 2011)

ISSN Print: 2157-9423   ISSN Online: 2157-9431

Google-based Impact Factor: 0.67  Citations  

Nonlinear Intestinal Absorption of Fluorescein Isothiocyanate Dextran 4, 000 Caused by Absorptive and Secretory Transporting System

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DOI: 10.4236/pp.2011.23025    6,002 Downloads   11,324 Views  Citations

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ABSTRACT

The mechanism of the nonlinear concentration dependence of the intestinal absorption of fluorescein isothiocyanate dextran 4,000 (FD-4) was studied using in situ rat intestinal loops and the in vitro Ussing-type chamber method. The intestinal absorption rate constant of FD-4, as evaluated by the intestinal loop method, increased significantly in a nonlinear fashion as the FD-4 concentration increased up to 0.2 mM and tended to decrease at concentrations higher than 0.2 mM. The mucosal-to-serosal permeation of FD-4 across rat ileal sheets, as evaluated by the in vitro Ussing-type chamber method, also increased in a nonlinear fashion in the low concentration range (0.01 - 0.02 mM), before decreasing as the concentration increased further, whereas serosal-to-mucosal permeation decreased in a concentration-dependent manner. In addition, mucosal-to-serosal flux and serosal-to-mucosal flux were increased and reduced in the presence of the metabolic inhibitor 2, 4-dinitrophenol, respectively. These results suggest that FD-4 is predominantly secreted into the intestinal lumen by an efflux transport system.

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Tomita, M. , Ohkubo, R. , Ouchi, S. , Kawahata, C. and Hayashi, M. (2011) Nonlinear Intestinal Absorption of Fluorescein Isothiocyanate Dextran 4, 000 Caused by Absorptive and Secretory Transporting System. Pharmacology & Pharmacy, 2, 173-179. doi: 10.4236/pp.2011.23025.

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