Ontogenetic and regional changes in α-methyl-d-glucoside andl-proline intestinal transport in guinea pig.

Regional brush-border uptakes of α-methyl-d-glucose andl-proline as well as morphometric parameters were studied from birth until adulthood in guinea pig small intestine. Intestinal weight, length, and area were fitted to two-segmented straight lines: from birth until the 2nd wk there was a sharp rise, whereas from day 14 to the adult stage the increase was slower. In everted sleeves, total uptakes of α-methyl-d-glucoside were higher on day 1 in duodenum, jejunum, and ileum, diminishing with increasing age. The initial fluxes ofl-proline were higher during the 1st wk, diminishing to values that kept constant thereafter. Total uptakes of l-proline relative to α-methyl-d-glucoside showed a peak in the 1st wk in the three segments studied, reflecting the high demand for protein during the postnatal period. Regional ratios ofl-proline to α-methyl-d-glucoside indicated that the ileum is the segment best suited to transporting this amino acid during the first 3 wk. Changes observed in the present study indicated a different pattern between hexose and amino acid transport during development and along the small intestine of guinea pig.