Effect of ethanol on disaccharidases of hamster jejunal brush border membrane.

1979 ◽  
Vol 237 (1) ◽  
pp. E68
Author(s):  
P K Dinda ◽  
R O Hurst ◽  
I T Beck
Keyword(s):  
Alkaline Phosphatase ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Kinetic Studies ◽  
Time Dependent ◽  
Acute Exposure ◽  
Dependent Manner ◽  
Brush Border Enzyme ◽  
Dose Dependent

This study was undertaken to investigate the effect of alcohol on the activity of jejunal disaccharidases (DS). The activity of DS in a preparation of purified brush border membrane of hamster jejunum was measured in the absence and in the presence (0.8 to 6.4% wt/vol) of ethanol. To compare the effect of alcohol on DS with its action on a brush border enzyme of a different group, we also measured the activity of alkaline phosphatase (AP) under similar conditions. Ethanol depressed the activity of sucrase, maltase, and lactase in a dose-dependent and time-dependent manner, but it stimulated the activity of AP. The ethanol-induced inhibition of DS was completely reversible. Kinetic studies indicate that ethanol depressed the Vmax and increased the Km of sucrase and lactase. The Vmax of maltase also decreased, but the Km of this hydrolase was not affected by ethanol. From the results of this study it would appear that acute exposure of the jejunal brush border to ethanol depresses the DS activity of the membrane and that (because the AP was not depressed) the ethanol-induced inhibition of DS is not the result of a general inhibition of all enzymes of the brush border.

Effect of ethanol on peptidases of hamster jejunal brush-border membrane

1982 ◽  
Vol 242 (5) ◽  
pp. G442-G447
Author(s):  
P. K. Dinda ◽  
I. T. Beck
Keyword(s):  
Conformational Changes ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Kinetic Studies ◽  
Inhibitory Effect ◽  
Time Dependent ◽  
Peptidase Activity ◽  
Dependent Manner ◽  
Dose Dependent ◽  
Hydrolysis Of

This study was undertaken to investigate the effect of ethanol on the brush-border activity of the small intestine. Brush-border membrane isolated from hamster jejunum was incubated with L-phenylalanylglycine (Phe-Gly), L-leucylglycine (Leu-Gly), or glycyl-L-tyrosine (Gly-Tyr) in the absence and presence of 1-5% (wt/vol) ethanol, and the L-amino acids liberated were determined. Ethanol was found to depress the hydrolysis of all peptides in a dose-dependent manner. The inhibitory effect of ethanol on the peptidases does not appear to be time dependent. The ethanol-induced inhibition of peptidase activity is completely reversible. Kinetic studies indicate that ethanol caused a decrease in the Vmax of the enzymes responsible for the hydrolysis of the Phe-Gly and Gly-Tyr but did not have any effect on their Km. In the hydrolysis of Leu-Gly, two enzymes were involved, and ethanol depressed the Vmax of both without affecting the Km of either. These findings suggest that ethanol produces conformational changes of the peptidases involved in the hydrolysis of these three dipeptides.

High-affinity paroxetine binding to the human placental serotonin transporter

1990 ◽  
Vol 259 (2) ◽  
pp. C196-C204 ◽  
Author(s):  
D. R. Cool ◽  
F. H. Leibach ◽  
V. Ganapathy
Keyword(s):  
Serotonin Transporter ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Binding Capacity ◽  
Membrane Vesicles ◽  
Dependent Manner ◽  
High Affinity ◽  
Paroxetine Binding ◽  
Dose Dependent ◽  
Dissociation Constant Kd

We investigated the interaction of paroxetine, a nontricyclic antidepressant, with the serotonin transporter of the human placental brush-border membrane. Paroxetine bound to the purified placental brush-border membranes with a high affinity [dissociation constant (Kd) = 72 pM]. The maximal binding capacity (Bmax) was 3.9 pmol/mg protein. Imipramine, desipramine, and serotonin inhibited the binding in a dose-dependent manner with inhibition constant (Ki) values of 4.4 nM, 48.7 nM, and 1.77 microM, respectively, whereas reserpine, ketanserin, and 5-hydroxytryptophan did not have any effect. Imipramine and serotonin inhibited paroxetine binding by increasing the Kd with essentially no effect on Bmax. Binding of paroxetine to the membranes increased hyperbolically with increasing concentrations of Na+ in the assay medium. Cl- had little effect on the binding. The effect of Na+ was primarily to increase the affinity of the transporter for paroxetine with no effect on Bmax. The association constant (Ka) increased hyperbolically as the concentration of Na+ increased, indicating a 1Na+:1paroxetine stoichiometry. The maximal value for Ka was 12.1 +/- 2.5 x 10(12) M-1, and Kd for Na+ was 10.0 +/- 3.5 mM. Treatment of the membranes with tyrosyl group-specific reagents reduced the Na(+)-dependent binding, suggesting the involvement of tyrosyl residues in the binding process. This inhibition was, however, significantly reduced when treatment with the reagent was performed in the presence of Na+, suggesting that the reactive tyrosyl residues were located at or near the Na(+)-binding site. Paroxetine inhibited NaCl gradient-dependent serotonin uptake in placental brush-border membrane vesicles both at pH 6.5 and 7.5.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of membrane fluidizing agents on renal brush border proton permeability

1985 ◽  
Vol 249 (6) ◽  
pp. F933-F940 ◽  
Author(s):  
H. E. Ives ◽  
A. S. Verkman
Keyword(s):  
Water Transport ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Fold Increase ◽  
Dependent Manner ◽  
Transport Pathway ◽  
Ph Gradients ◽  
Orange Fluorescence ◽  
Dose Dependent

H+ permeability (PH) of brush border membrane vesicles isolated from rabbit renal cortex was measured from the rate of collapse of preformed pH gradients using acridine orange fluorescence quenching. n-Alkanols increased PH from 0.005 to 0.1 cm/s in a dose-dependent manner. At 25 degrees C, PH increased to 0.01 cm/s at [n-alkanol] = 90 mM (butanol), 30 mM (pentanol), 7 mM (hexanol), and 1.8 mM (heptanol). Activation energy (Ea) of PH was 21.6 kcal/mol (5-50 degrees C), which decreased to 18.5 kcal/mol in the presence of either 200 mM butanol or 12 mM hexanol. Membrane fluidity was estimated from diphenylhexatriene anisotropy (r). n-Alkanols decreased r from 0.25 to 0.18 in a dose-dependent manner. At 25 degrees C, r = 0.22 at [n-alkanol] = 200 mM (butanol), 27 mM (pentanol), 9.5 mM (hexanol), and 2 mM (heptanol). The effects of n-alkanols on PH and r correlated well with known n-alkanol lipid-water partition coefficients. Similar increases in PH and decreases in r were observed for nonalkanol lipid anesthetics. The effects of n-alkanols on the Na+-H+ antiporter and on osmotically driven water transport were also studied. At concentrations of n-alkanol that resulted in a 10-fold increase in PH, there was no significant effect on either Na+-H+ exchange or water transport. These results suggest a lipid pathway for brush border H+ diffusion that is distinct from both the Na+-H+ antiporter and the water transport pathway.

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.

Alkaline phosphatase: A marker enzyme for brush border membrane

1972 ◽  
Vol 28 (4) ◽  
pp. 385-386 ◽  
Author(s):  
U. Schmidt ◽  
U. C. Dubach ◽  
I. Bieder ◽  
B. Funk
Keyword(s):  
Alkaline Phosphatase ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Marker Enzyme

scholarly journals Genotoxic and Histopathological Effects of Chlorpyrifos on African Catfish, C. gariepinus and Ameliorative Potentials of Ackee Apple, blighia sapida Seed

2018 ◽  
Vol 6 (1) ◽  
pp. 1 ◽  
Author(s):  
Oluyinka Iyiolai ◽  
A. A. Adeagbo ◽  
W. S. Weliange ◽  
S. I. Abdulkareem ◽  
Anifowoshe T. Abass ◽  
...  
Keyword(s):  
Chronic Exposure ◽  
Clarias Gariepinus ◽  
Aquatic Organisms ◽  
Acute Exposure ◽  
Histopathological Analysis ◽  
African Catfish ◽  
Dependent Manner ◽  
Dose Dependent ◽  
Histopathological Effects ◽  
Positive Controls

Chlorpyrifos (CPF) is a very toxic pesticide commonly used for controlling agriculturally important pests. The present study investigates DNA damaging effects of CPF on Clarias gariepinus was assessed using genetic assays. Fish were exposed to varying concentrations of CPF (100ppm, 200ppm and 300ppm) at 96 hours (acute exposure). LC50 of the pesticide was found to be 120ppm and one-tenth of the LC50 (12ppm) was taken for the chronic exposure. Distilled water and colchicine were used as negative and positive controls respectively. After 28 days of chronic exposure, fish were fed with inclusion of B. sapida seed (powder) for 14 days. Liver and gills of the fish were removed following 96h exposure, days 7, 14 and 28 of the chronic exposure as well as after the period of amelioration (14 days) for CA assay and histopathological analysis. The results of CA assay showed statistically significant (p ˂ 0.05) increase in CA in a dose-dependent manner for all the exposed groups after acute exposure and time dependent after chronic exposure. Also, this study showed that CPF can potentially induce genotoxic and histopathological changes in fish and other aquatic organisms.

Role of Alkaline Phosphatase in Phosphate Uptake into Brush Border Membrane Vesicles from Human Intestinal Mucosa

1985 ◽  
Vol 97 (5) ◽  
pp. 1461-1466 ◽  
Author(s):  
Kazuyuki HIRANO ◽  
Yuichi IIIZUMI ◽  
Yukio MORI ◽  
Kazumi TOYOSHI ◽  
Mamoru SUGIURA ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Intestinal Mucosa ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Phosphate Uptake ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles

Pattern of rat intestinal brush-border enzyme gene expression changes with epithelial growth state

1995 ◽  
Vol 269 (2) ◽  
pp. C385-C391 ◽  
Author(s):  
R. A. Hodin ◽  
S. M. Chamberlain ◽  
S. Meng
Keyword(s):  
Gene Expression ◽  
Alkaline Phosphatase ◽  
Brush Border ◽  
Longitudinal Axis ◽  
Mrna Levels ◽  
Intestinal Alkaline Phosphatase ◽  
Enzyme Gene ◽  
Growth State ◽  
Brush Border Enzyme ◽  
Epithelial Growth

Enterocyte growth and differentiation occur simultaneously within the epithelium, but little is known regarding any relationship between these two processes. Four rat models of small intestinal epithelial hypo- and hyperplasia (neonatal ontogeny, fasting/refeeding, hypo-/hyperthyroidism, and bombesin treatment) were used to study the regulation of enterocyte gene expression in relation to epithelial growth state. Mucosal scrapings, as well as crypt and villus cell populations, were subjected to Northern blot analyses using radiolabeled cDNA probes corresponding to lactase, intestinal alkaline phosphatase, villin, ornithine decarboxylase (ODC), and the actin control. In all four models, the hypoplastic (atrophic) condition is characterized by high levels of lactase and low levels of the 3.0-kb intestinal alkaline phosphatase mRNA, whereas under hyperplastic conditions this pattern is reversed. The changes in intestinal alkaline phosphatase and lactase are qualitatively similar along the longitudinal axis of the intestine and are proportional to the degree of hyperplasia, as verified by ODC mRNA levels. Furthermore, the crypt-villus axis of differentiation is maintained regardless of epithelial growth state. In conclusion, the pattern of brush-border enzyme gene expression changes as a function of epithelial growth state, indicating a previously unrecognized degree of plasticity to the state of enterocyte differentiation.

Na+/H+ antiporter in membrane populations resolved from a renal brush border vesicle preparation

1984 ◽  
Vol 246 (6) ◽  
pp. F853-F858
Author(s):  
A. K. Mircheff ◽  
H. E. Ives ◽  
V. J. Yee ◽  
D. G. Warnock
Keyword(s):  
Alkaline Phosphatase ◽  
Cytochrome C ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Leucine Aminopeptidase ◽  
Membrane Preparation ◽  
Phase System ◽  
Cytochrome C Reductase ◽  
Nadph Cytochrome ◽  
Nadph Cytochrome C Reductase

A conventional brush border membrane preparation, obtained by divalent cation precipitation of homogenates of rabbit renal cortex, was analyzed by countercurrent distribution in an aqueous dextran:polyethylene glycol two-phase system. The resulting fractions were assayed for the presence of the Na+/H+ antiporter and for a variety of biochemical marker enzymes. This analysis revealed four physically distinct membrane populations (A-D). Population A consisted of two subpopulations, A' and A", which were enriched an average of 49-fold in maltase; they were also highly enriched in alkaline phosphatase, leucine aminopeptidase, and Na+/H+ antiporter. On the basis of their marker contents, populations A' and A" appear to represent highly purified, functional brush border membrane vesicles. Population B was enriched twofold in NADPH-cytochrome c reductase and population C was enriched 12-fold in galactosyltransferase. Populations B and C accounted for 25% of the protein in the starting material and appear to reflect contamination of the brush border membrane preparation by subpopulations of endoplasmic reticulum and Golgi fragments. Population D was enriched in Na+/H+ antiporter, alkaline phosphatase, leucine aminopeptidase, Na-K-ATPase, and acid phosphatase but not maltase, NADPH-cytochrome c reductase, galactosyltransferase, or succinate dehydrogenase. Its identity is unclear, and it might consist of a multiplicity of populations from different origins.

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