The role of brush border enzymes in tubular reabsorption of disaccharides

1977 ◽  
Vol 371 (1-2) ◽  
pp. 141-145 ◽  
Author(s):  
Stefan Silbernagl ◽  
Gertraud Vetter
Keyword(s):  
Brush Border ◽  
Tubular Reabsorption ◽  
Brush Border Enzymes

scholarly journals A rapid method for the preparation of microvilli from rabbit kidney

1974 ◽  
Vol 142 (3) ◽  
pp. 575-581 ◽  
Author(s):  
Andrew G. Booth ◽  
A. John Kenny
Keyword(s):  
Brush Border ◽  
Plasma Membranes ◽  
Rabbit Kidney ◽  
Cortical Tissue ◽  
Acid Hydrolases ◽  
Simple Method ◽  
Brush Border Enzymes ◽  
Low Speed ◽  
Bivalent Metal Ions

A simple method for the isolation of microvilli from kidney brush border is described. The method depends on the preferential aggregation of other subcellular structures by bivalent metal ions. MgCl2 is added to a homogenate of cortical tissue prepared from frozen rabbit kidneys. Aggregated material is removed by a low-speed centrifugation and the supernatant centrifuged at 15000g to yield a pellet enriched in microvilli. This is resuspended and given a second treatment with Mg2+. The purified preparation is obtained after four short differential centrifugations. The six brush-border enzymes that were monitored were enriched 11–17-fold compared with the original homogenate and were obtained in about 10% yield. Marker enzymes for other subcellular components showed the preparation to be essentially free of mitochondria and to be less contaminated with endoplasmic reticulum and baso-lateral plasma membranes than are conventional brush-border preparations. The main contamination was of lysosomal origin, about half of which was attributable to adsorbed acid hydrolases rather than to intact lysosomes. The aggregated components in the low-speed pellet bound less Mg2+than did the microvillus fraction. A possible mechanism for the role of Mg2+is discussed.

Role of glucocorticoids on the maturation of brush border enzymes in fetal rat gut endoderm

1983 ◽  
Vol 39 (10) ◽  
pp. 1150-1152 ◽  
Author(s):  
M. Kedinger ◽  
P. M. Simon-Assmann ◽  
B. Lacroix ◽  
K. Haffen
Keyword(s):  
Brush Border ◽  
Brush Border Enzymes ◽  
Fetal Rat ◽  
Gut Endoderm ◽  
Rat Gut

Role of basolateral cell membranes in organic solute reabsorption in rabbit kidneys

1987 ◽  
Vol 252 (6) ◽  
pp. F1042-F1047
Author(s):  
E. C. Foulkes
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Brush Border ◽  
Tubular Reabsorption ◽  
Cellular Transport ◽  
Organic Solute ◽  
Transport Inhibitors ◽  
Carrier Systems ◽  
Heavy Metal Intoxication

The present work explores the contributions of basolateral carrier systems in tubular reabsorption of organic solutes. Reabsorption of sugars and amino acids, as previously shown, can be represented by a three-compartment linear model that predicts that 1) if basolateral transport contributes to sugar reabsorption, alpha-methylglucoside reabsorption compared with that of glucose should be characterized by a longer transepithelial transit time (TET) and a correspondingly increased cellular transport pool (S), and 2) saturation of basolateral amino acid carriers, or presence of competing amino acids or other basolateral transport inhibitors, should prolong TET of a test amino acid, and increase S above the expected value. Both predictions were fully confirmed. Heavy metal intoxication not only inhibits transport of amino acids at the brush border, but also prolongs their TET and increases the size of S for a given reabsorbed load. Basolateral extrusion of amino acids is more sensitive to metals than is uptake across the brush border. Although basolateral carriers accelerate return of reabsorbed solute to blood, their contribution to reabsorption does not seem to be mandatory.

Different diuresis-dependent excretions of urinary enzymes: N-acetyl-beta-D-glucosaminidase, alanine aminopeptidase, alkaline phosphatase, and gamma-glutamyltransferase.

1986 ◽  
Vol 32 (3) ◽  
pp. 529-532 ◽  
Author(s):  
K Jung ◽  
G Schulze ◽  
C Reinholdt
Keyword(s):  
Alkaline Phosphatase ◽  
Brush Border ◽  
Excretion Rate ◽  
Urine Flow ◽  
High Intake ◽  
Brush Border Enzymes ◽  
Urinary Creatinine ◽  
Gamma Glutamyltransferase ◽  
Alanine Aminopeptidase ◽  
Brush Border Enzyme

Abstract We studied how much of the lysosomal enzyme N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30) and of the brush-border enzymes alanine aminopeptidase (EC 3.4.11.2), alkaline phosphatase (EC 3.1.3.1), and gamma-glutamyltransferase (EC 2.3.2.2) was excreted in urine over 8 h after a high intake of fluid (22 mL per kilogram of body weight). The hourly excretion of all four enzymes increased with the increasing urine flow rate. The excretion rate of the brush-border enzymes was more markedly influenced than that of N-acetyl-beta-D-glucosaminidase. By relating the enzyme excretion to urinary creatinine we could reduce the variability of brush-border enzyme output and could completely compensate for the effect of diuresis on the excretion of N-acetyl-beta-D-glucosaminidase.

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