Absorption and Distribution for Subtoxic Level of Selenite by Vascularly Perfused Small Intestine in Rats

Abstract

Intestinally absorptive and distributive aspects of the subtoxic level of selenite in rats were investigated using a double perfusion system. The double-perfusion technique is an in situ, in vitro preparation in which the intestinal lumen and its vasculature are perfused simultaneously. In the previous study, the subtoxic level of sodium selenite was determined to be 1.2 mM through inhibition of 3-0-methyl glucose (3MG) absorption. Thus, the selenite used to identify the intestinally absorptive mechanism of selenite was perfused at a luminal concentration of 1, 10, 50, 100 and 200 μM. Appearance of radiolabeled-Selenium (Se) was identified in three compartments: luminal perfusate, small intestine and vascular perfusate. Dose-response curves for Se in the three compartments indicate that selenite is absorbed by non-mediated passive diffusion. Regarding the distributive aspect, 21.02±3.92% of the total amount of selenite in the lumen was transported into the blood vessels across the small intestine. However, 4.75±1.75% of the total amount of selenite in the lumen is retained by the small intestine. Therefore, a total of 25.67±4.46% of the test dose was taken up from the luminal perfusate.