Quantifying Intestinal Glucose Absorption Using Isolated Vascularly Perfused Rat Small Intestine

Intestinal glucose absorption has been studied for several decades. However, the different methods available for investigating absorption are often the reason for variability in the results, and it is difficult to measure the relative contribution of paracellular absorption using existing methods. Thus, we have established a new model for measuring glucose absorption. In the isolated in situ vascularly perfused small intestine, the intestinal epithelium is completely preserved, and the entire transport pathway is intact. In the present model, we use radioactive labeled ¹⁴C-d-glucose, which allows for sensitive quantification of glucose absorption even with low luminal concentrations. The described method is optimized for intestinal glucose absorption but can be applied to other macro/micronutrients that can be radioactively labeled. The described procedure is a novel approach for measurements of intestinal nutrient absorption and gut permeability in which luminal nutrient concentrations resemble physiological concentrations. Key features • Sensitive quantification of intestinal glucose absorption at physiologically relevant luminal glucose concentrations. • Accurate distinction between transcellular vs. paracellular glucose absorption using mannitol as an indicator of paracellular intestinal absorption. • Differentiation between apical and basolateral pathways for transport across the intestinal epithelium.