Intestinal absorption of sugars : effect of aging

Studies of intestinal sugar transport during ageing have received more attention recently than in the past. However, the results obtained to date have been contradictory, presumably because of the different animal species and strains used, the different methodologies employed and the different ages of animals studied which makes a direct comparison of the results more difficult. Nevertheless, some findings deserve attention because they have been repeatedly confirmed. Studies of the ageing gut involve differing fields of investigation including morphology and morphometry, studies of chemical composition and physical properties, qualitative and quantitative enzyme activity of enterocytes and their plasma membranes and characteristics of transport mechanisms and permeability. Recent reviews have highlighted different aspects of gut physiology and biochemistry during ageing. The present report includes studies perfected in the past few years in our laboratory on effects of ageing on the transport of sugars, Na+ and fluid in the rat jejunum and ileum. Initially our studies were done in an integrated system, under in vivo conditions and subsequently in the everted, cannulated and perfused gut in vitro. Finally studies were performed on the brush-border membrane (BBM), which controls the entry of solutes into the cell.