title: Sodium-dependent D-glucose transport in brush-border membrane vesicles from isolated rat small intestinal villus and crypt epithelial cells.
abstract: Differentiation and maturation of enterocytes occur with migration from the crypt to villus compartments. To investigate the effect of epithelial cell differentiation on sodium-dependent D-glucose transport, brush-border membrane vesicles were prepared from small intestinal epithelial cell suspensions selectively isolated from villus and crypt populations. Enterocytes were isolated with a morphologically monitored sequential cell dissociation method. Thymidine kinase, sucrase, and alkaline phosphatase activities were measured as differentiation markers of specific cell populations. Brush-border membrane vesicles were purified and their kinetic characteristics defined with a rapid filtration method under conditions of a zero-trans, 100 mM cis-NaSCN gradient. Typical "overshoot" phenomena characteristic of sodium D-glucose cotransport were observed for both villus (five- to eight-fold equilibrium values) and crypt brush-border membrane vesicles (two- to four-fold equilibrium values). Kinetics analyses of the initial D-glucose flux in brush-border membrane vesicles suggested the presence of at least two sodium-dependent D-glucose carriers in the villus and only a single carrier in the crypt compartments. These data indicate that sodium D-glucose cotransport occurs in brush-border membranes of both villus and crypt populations. Moreover, quantitative and qualitative differences between these two membrane populations suggest that epithelial D-glucose transport processes are differentiation dependent and reflect the degree of enterocyte development.
mesh_terms: D000818:Animals; D004848:Epithelium / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D007421:Intestine, Small / Q000166:cytology / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008871:Microvilli / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D009004:Monosaccharide Transport Proteins; D005947:Glucose