Sodium-dependent D-glucose transport in brush-border membrane vesicles from isolated rat small intestinal villus and crypt epithelial cells

1987 ◽  
Vol 65 (6) ◽  
pp. 1213-1219 ◽  
Author(s):  
H. J. Freeman ◽  
G. Johnston ◽  
G. A. Quamme
Keyword(s):  
Epithelial Cell ◽  
Glucose Transport ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Transport Processes ◽  
Brush Border Membrane Vesicles ◽  
Filtration Method ◽  
Sodium Dependent ◽  
Small Intestinal

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.

Age-related changes in sodium-dependent glucose transport in rat small intestine

1986 ◽  
Vol 251 (2) ◽  
pp. G208-G217 ◽  
Author(s):  
H. J. Freeman ◽  
G. A. Quamme
Keyword(s):  
Small Intestine ◽  
Glucose Transport ◽  
Brush Border ◽  
Brush Border Membrane ◽  
High Capacity ◽  
Membrane Vesicles ◽  
Distal Segment ◽  
Brush Border Membrane Vesicles ◽  
Transport Systems ◽  
Sodium Dependent

Brush-border membrane vesicles were purified from jejunoileal segments of rats ranging from 3 to 156 wk. The kinetics of sodium-dependent glucose cotransport were studied under voltage-clamped, zero trans conditions over a wide range of cis-glucose concentrations (0.005-1.5 mM). Initial glucose uptake in brush-border membrane vesicles isolated from the proximal intestinal segment (50 cm from ligament of Treitz) of rats less than 7-8 wk of age demonstrated a distinct curvilinear Hofstee plot consistent with multiple-transport mechanisms. One system possessed an apparent Vmax of 10.6 +/- 0.5 nmol X mg prot-1 X min-1 and Km of 630 +/- 18 microM. The second system was characterized by Vmax of 0.9 +/- 0.1 nmol X mg prot-1 X min-1 and Km of 12 +/- 1 microM. In contrast, the distal segment (50 cm to end of small intestine) possessed only one sodium-dependent glucose carrier system. The apparent Vmax and Km were 1.11 +/- 0.20 nmol X mg protein-1 X min-1 and 49 +/- 7 microM, respectively. Sodium-activation curves in the presence of 0.3 and 0.03 mM glucose were consistent with more than one sodium ion with both systems. In contrast, rats 12-13 wk old and older possessed both sodium-dependent transport systems in the proximal early and distal small intestine. The high-capacity system is more abundant in the proximal than the distal segment. These data suggest that, under these specific conditions, there are two sodium-dependent glucose carriers in the intestine of young rats: one located in the jejunum characterized by high capacity and low affinity, and the second located throughout the jejunoileum characterized by low capacity and high affinity. Furthermore with age there is a development of the low-affinity system in the distal segments so that both systems are found along the length of the jejunum and ileum. Accordingly, serial and parallel heterogeneity of sodium-dependent glucose transport exists along the small intestine.

Regulation of Na+-Pi cotransport by 1,25-dihydroxyvitamin D3 in rabbit duodenal brush-border membrane

1982 ◽  
Vol 242 (5) ◽  
pp. G533-G539 ◽  
Author(s):  
B. Hildmann ◽  
C. Storelli ◽  
G. Danisi ◽  
H. Murer
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Precipitation Method ◽  
Dihydroxyvitamin D3 ◽  
1,25 Dihydroxyvitamin D3 ◽  
Pi Transport ◽  
Sodium Dependent ◽  
Cotransport System

Brush-border membrane vesicles were isolated from rabbit duodenum by a Mg2+ precipitation method, and phosphate transport was analyzed by a rapid filtration technique. Uptake of inorganic phosphate (Pi) was stimulated by an inwardly directed sodium gradient, indicating the operation of a Na-Pi cotransport system in brush-border membrane vesicles. Treatment of the animals with ethane-1-hydroxy-1,1-diphosphonate (EHDP), which is known to decrease the circulating levels of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], reduced within 3 days the sodium-dependent Pi transport in the brush-border vesicles. Injections of 1,25(OH)2D3 into rabbits increased within 9 h the sodium-dependent Pi transport in membranes from EHDP-treated animals as well as in untreated ones. The Na-D-glucose cotransport system appeared to be unaffected by these maneuvers. These results suggest that the Na-Pi cotransport system is an important site of regulation of intestinal transepithelial Pi transport by 1,25(OH)2)D3.

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