Glucose metabolism during ontogeny of intestinal active sugar transport in the chick.

1. Glucose transport, uptake, utilization, and lactate production by intestinal slices from embryos and young chicks have been determined by means of the in vitro tissue accumulation method. Changes in these parameters with age, after feeding, and in the presence of phlorrhizin have been measured, in most cases, under both aerobic and anaerobic conditions.2. The embryonic intestine, 3 days before hatching, took up and utilized only a negligible quantity of glucose from the incubating medium and net lactate production was limited. The transport and utilization of exogenous sugar thus seem to be minimal at this age.3. On the day of hatching, the intestine concentrated and utilized glucose, and lactate production was significant as was the inhibition of glucose uptake by phlorrhizin. This capacity to metabolize exogenous sugar appears to be consequent to onset of function of the sugar transport mechanism just before hatching.4. At 2 days of age intestinal slices concentrated and utilized more glucose than at 0 days of age, if the chicks were not fed. After eating, glucose transport was decreased while lactate production was enhanced. Feeding schedules thus influence sugar transport and metabolism by the young chick intestine.5. The metabolic parameters measured showed essentially the same relationships in intestinal slices from 8- and 36-day-old chicks as in 2-day-old birds. Although there were indications that intestinal maturation continues well into post-natal life, the most striking changes in functional capacity, observed in these studies, occurred during the several days around hatching.