[Glucose absorption from the small intestine in rats of different ages (authors transl)].

Glucose absorption from the ageing rat's small intestine was studied "in vivo" using the recirculation-perfusion method of Sheff and Smyth. Different initial concentrations were used and animals of various ages (6 mo., 12 mo. and more than 27 mo. old) tested for their glucose uptake from the total small intestine (including duodenum) in the course of a twenty-minute period. Glucose was estimated by the modified o-toluidine method of Hultman. The (reciprocal) absorption data, reduced on dried intestine weight units were plotted by the Lineweaver -- Burk (regression) equations and the Km and Vmax indices derived. The results show that there is an apparent increase of the Km value in case of the old rats. Regarding the Km as an apparent affinity constant of the glucose for the carrier transport, ageing induces a considerable loss in affinity and a concomitant increase of the maximum absorptive capacity (Vmax) possible by the transfer capacity of the ageing small gut. The interpretation of the data suggest that the role of the probable age-dependent changes of diffusion-components cannot be ruled out.