Developmental change of interrelationship between sugar-, amino acid- or peptide-evoked potential and influx across the mucosal border in the small intestine.

In this study, the electrical resistance of guinea pig small intestine was examined during postnatal development in vitro. The interrelationship between sugar-, neutral amino acid- or peptide-current calculated from potential difference and their influxes across the mucosal border of the small intestine was also investigated during postnatal development. At all stages from one week to adult animal, the electrical resistance remained at nearly the same value. Currents of glucose, maltose and lactose corresponded with influxes at any stage and these sugars were completely carried by an active transport system from the period of lactation. Glycine might be actively transported at any stage of development. Therefore the transmural potential differences induced by these substances are adequate indices of intestinal absorptive capacities. On the other hand, glycyl-glycine transport was independent of Na+ and glycyl-glycine induced PD does not reflect the influx.