Absorption of glucose by lamb proximal colon measured during early postnatal development

Abstract

SUMMARYPieces of proximal colon taken from lambs during the first 2 weeks of postnatal life were incubated in vitro for measurement of short-circuit current and unidirectional glucose fluxes.The short-circuit current of colons taken from newborn and 1-day-old lambs was increased significantly in the presence of 5 mM D-glucose. This is taken as evidence for the presence of an active transport system for monosaccharides in this tissue. No such effect was seen using colons taken from 2-week-old lambs.Direct measurement of glucose transport showed a net absorption to take place across the proximal colon of newborn and 1-day-old lambs. There was no net movement across colons taken from lambs aged 1 week and over. Essentially similar results were obtained when measuring the amount of glucose influx inhibited by 10−5 M phloridzin.Colonic decline of glucose transport follows a time course different from that reported previously for the small intestine. It probably arises from rapid maturation of the colonic mucosa postnatally rather than from any gradual absence of substrate occurring during rumen development.