Kinetics of intestinal sugar transport, in vivo

Sugar absorption by the small intestine has been studied in rat and hamster in vivo, with luminal perfusion, during 1 minute successive periods. Transport is calculated as the difference between absorption and diffusion. The diffusion component is evaluated in the presence of phlorizin or as absorption of sorbose. The resulting KT values for glucose and galactose (rat: 7.7 and 10 mM; hamster: 10 and 14 mM) and 3-0-methyl-glucose (hamster: 25-33 mM) are quite lower than those previously obtained in vivo, but still higher than those in vitro. The physiological levels of glucose in the intestine of normally fed animals imply that the diffusion component plays an important role in the proximal regions of the small intestine, especially in rat.