ACTIVE-TRANSPORT OF 3-O-METHYL-GLUCOSE BY THE SMALL-INTESTINE IN CHRONICALLY CATHETERIZED RATS

A method is described for determining the fraction of intestinal 3-O-methyl-glucose (30MG) absorption that occurs by active transport in chronically catheterized rats without the influence of anesthesia or surgical bowel manipulation. That fraction was determined by simultaneously measuring portal venous-aortic blood concentration gradients (Delta C) of 3-O-methyl-glucose (30MG) and L-glucose, metabolically inert analogues of D-glucose, 30MG is actively and passively absorbed by the same mechanisms as D-glucose, L-glucose is only passively absorbed. The fraction of 30MG that is actively transported was calculated from the difference between 30MG and L-glucose absorption, divided by total 30MG absorption. We found that more than 94% of 3-O-methyl-glucose is absorbed by active transport when luminal concentrations range from 50 to 400 mM. We conclude that in unrestrained, unanesthetized chronically catheterized rats, most 30MG is actively absorbed by the intestine even at high luminal concentrations.