Species difference in mechanisms of D-xylose absorption by the small intestine.

Comparisons were made for the ability of D-xylose to evoke changes in the transepithelial potential difference upon its addition to the mucosal solution between guinea pig and rat small intestines. Also, Na+-dependence of D-xylose influx from the mucosal solution into epithelial cells, and the phlorizin-sensitivity of the influx, were compared between these animals. In guinea pig intestine, the sugar caused an immediate and sustained increase in the transmural potential difference, and this potential increment was completely abolished by phlorizin. In contrast, the sugar did not cause any electrical changes in the rat small intestine. The influx of D-xylose across the mucosal border was Na+-dependent and phlorizin-sensitive in guinea pigs, while it was Na+-independent and phlorizin-insensitive in rats. The results indicate that there is a qualitative difference in the mode of transport of D-xylose between guinea pigs and rats.