The adaptive response of disaccharidase activities at different sites along the villus epithelium after proximal intestinal resection in the rat. A microdensitometric study of enzyme kinetics.
The "in situ" kinetic constants (app. Km and Vmax) of brush border neutral alpha-glucosidase (EC 3.2.1.20) and lactase/beta-glucosidase (EC 3.2.1.21) were determined 4,6 (only alpha-glucosidase), and 12 days after 60% proximal intestinal resection in rat ileum at the villus base and the transition zone between middle and upper villus third by use of a quantitative biochemical analysis of enzymes in tissue sections (section biochemistry). Sham-operated rats served as controls, and the kinetic data (means per rat, time and villus position) were compared (n = 4 animals in each experimental group) first by an overall factorial analysis of variance and thereafter in detail using nonparametric test procedures. Both enzyme activities exhibited a differential response: No changes of lactase/beta-glucosidase kinetics, but a significant decrease in both Vmax- and Km-values of neutral alpha-glucosidase, which was already fully expressed on day 4 after resection and confined to the apical villus region still implying a basoapical increase of Vmax and thus maintaining the normal activity gradient on a lower level. In conclusion, a complex pattern of enzymatic adaptation to proximal intestinal resection ensues in the hyperplastic ileal mucosa which cannot be explained simply in terms of the hypothesis of cellular immaturity.
D000222:Adaptation, Physiological; D000818:Animals; D003720:Densitometry; D004186:Disaccharidases / Q000378:metabolism*; D005260:Female; D006965:Hyperplasia; D007081:Ileostomy; D007082:Ileum / Q000201:enzymology* / Q000473:pathology; D007413:Intestinal Mucosa / Q000201:enzymology* / Q000473:pathology; D007700:Kinetics; D008871:Microvilli / Q000201:enzymology; D051381:Rats; D011919:Rats, Inbred Strains; D000520:alpha-Glucosidases / Q000378:metabolism; D001617:beta-Glucosidase / Q000378:metabolism
D004186:Disaccharidases; D000520:alpha-Glucosidases; D001617:beta-Glucosidase