Effects of hyper- and hypothyroidism on carbonic anhydrase, Mg2+-dependent ATPase and Mg2+-dependent, HCO3−-stimulated ATPase activities of rat duodenal mucosa and kidney cortex

1990 ◽  
Vol 126 (1) ◽  
pp. 119-129 ◽  
Author(s):  
S. Suzuki ◽  
H. Chen ◽  
T. Takahashi ◽  
O. Niwa
Keyword(s):  
Enzyme Activity ◽  
Carbonic Anhydrase ◽  
Atpase Activity ◽  
Brush Border ◽  
Duodenal Mucosa ◽  
Kidney Cortex ◽  
Serum Concentrations ◽  
Dependent Atpase ◽  
Brush Borders ◽  
Thyroidal Status

ABSTRACT Carbonic anhydrase (CA) and Mg2+-dependent ATPase and Mg2+-dependent, HCO3−-dependent ATPase (Mg2+-HCO3−-ATPase) activities in rat duodenal mucosa and kidney cortex were examined with respect to thyroidal status. Administration of 50 and 150 μg thyroxine (T4)/kg per day s.c. for 7 days decreased duodenal cytosol CA activity to 66% of control with the former and 43% with the latter dose, while Mg2+-HCO3−-ATPase activity in brush borders of duodenal mucosa was increased to 116% of control by 150 μg T4/kg. CA and Mg2+-HCO3−-ATPase activities in the cytosol and brush border of kidney cortex did not change after administration of T4. Hypothyroidism induced by thyroidectomy for 2 and 4 weeks or administration of methimazole (2·5–20 mg/kg per day s.c. or peroral) for 2, 3 and 4 weeks all increased duodenal cytosol CA activity, to about 140% at 2 weeks and 153% at 4 weeks after thyroidectomy, and to about 136% after the oral administration of 10 mg methimazole/kg per day for 4 weeks, while brush border Mg2+-HCO3−-ATPase activity was decreased to 56% of control 4 weeks after thyroidectomy and to 74% after the s.c. administration of 20 mg methimazole/kg per day for 3 weeks. The increase in CA activity and the decrease in ATPase activity after thyroidectomy were restored to normal levels by replacement with T4. Neither enzyme activity in the kidney changed in hypothyroidism. Serum concentrations of T4 and cortisol-like material increased after administration of T4, and serum concentrations of T4, aldosterone and cortisol-like material all decreased in hypothyroidism. Correlations were observed between duodenal CA and Mg2+-HCO3−-ATPase activities and serum concentrations of T4 (P < 0·01). These results reveal that the decrease in CA activity and the increase in Mg2+-HCO3−-ATPase activity of duodenal mucosa in hyperthyroidism are reversed in hypothyroidism, while both enzyme activities in the kidney are unrelated to thyroidal status. Journal of Endocrinology (1990) 126, 119–129

Activities and subcellular localizations of enzymes implicated in gastroduodenal bicarbonate secretion

1984 ◽  
Vol 247 (2) ◽  
pp. G133-G139 ◽  
Author(s):  
D. Stiel ◽  
D. J. Murray ◽  
T. J. Peters
Keyword(s):  
Plasma Membrane ◽  
Carbonic Anhydrase ◽  
Atpase Activity ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Basolateral Membrane ◽  
Duodenal Mucosa ◽  
Carbonic Anhydrase Activity ◽  
Marker Enzymes ◽  
Alpha Glucosidase

Analytical subcellular fractionation of tissue whole homogenates and microanalysis of organelle marker enzymes were used to study the activity and subcellular localization of enzymes implicated in HCO3 secretion in rat duodenal and gastric antral mucosae. The following organelles, characterized by their marker enzymes, were located in the density gradients: cytosol (lactate dehydrogenase), plasma membrane (5'-nucleotidase), peroxisomes (catalase), mitochondria (succinate dehydrogenase), endoplasmic reticulum (Tris-resistant alpha-glucosidase), lysosomes (N-beta-acetylglucosaminidase), and brush-border membrane (Zn2+-resistant alpha-glucosidase and alkaline phosphatase). Compared with gastric antrum, rat duodenal mucosa contained over twice the activity of HCO3-ATPase and of Na+-K+-ATPase but less than one-tenth the activity of carbonic anhydrase. Duodenal HCO3-ATPase activity was observed in both mitochondrial and brush-border membrane fractions, whereas antral HCO3-ATPase activity was confined to mitochondria. Na+-K+-ATPase activity was found largely in the basolateral membrane (duodenum) and plasma membrane (antrum). In both tissues carbonic anhydrase activity was localized to the cytosolic fraction. These observations offer further evidence that differing biochemical mechanisms underlie HCO3 secretion by gastric and duodenal epithelia.

scholarly journals Role of myosin in terminal web contraction in isolated intestinal epithelial brush borders.

1985 ◽  
Vol 100 (5) ◽  
pp. 1647-1655 ◽  
Author(s):  
T C Keller ◽  
K A Conzelman ◽  
R Chasan ◽  
M S Mooseker
Keyword(s):  
Atpase Activity ◽  
Intestinal Epithelium ◽  
Brush Border ◽  
Time Course ◽  
Intestinal Epithelial ◽  
Terminal Web ◽  
Brush Borders

We have investigated the role of myosin in contraction of the terminal web in brush borders isolated from intestinal epithelium. At 37 degrees C under conditions that stimulate terminal web contraction (1 microM Ca++ and ATP), most (60-70%) of the myosin is released from the brush border. Approximately 80% of the myosin is also released by ATP at 0 degree C, in the absence of contraction. Preextraction of this 80% of the myosin from brush borders with ATP has no effect on either the time course or extent of subsequently stimulated contraction. However, contraction is inhibited by removal of all of the myosin with 0.6 M KCl and ATP. Contraction is also inhibited by an antibody to brush border myosin, which inhibits both the ATPase activity of brush border myosin and its ability to form stable bipolar polymers. These results indicate that although functional myosin is absolutely required for terminal web contraction only approximately 20% of the brush border myosin is actually necessary. This raises the possibility that there are at least two different subsets of myosin in the terminal web.

scholarly journals ULTRATHIN FROZEN SECTIONS

1967 ◽  
Vol 34 (3) ◽  
pp. 773-786 ◽  
Author(s):  
Elizabeth H. Leduc ◽  
W. Bernhard ◽  
S. J. Holt ◽  
J. P. Tranzer
Keyword(s):  
Enzyme Activity ◽  
Brush Border ◽  
Distal Tubule ◽  
Kidney Cortex ◽  
Mitochondrial Atpase ◽  
Frozen Sections ◽  
Enzyme Cytochemistry ◽  
Thin Sections ◽  
Ultrathin Frozen Sections ◽  
Structural Preservation

Endogenous enzyme activity can be readily and routinely demonstrated in ultrathin, frozen sections for electron microscopy. The procedure employed to obtain the best structural preservation as well as enzyme activity in thin sections involved fixation in glutaraldehyde, embedding in thiolated gelatin or pure gelatin, partial dehydration in glycerol, and sectioning in a cryostat at -35°C with a slightly modified Porter-Blum microtome on which the tissue is maintained at -70°C and the knife at -23°C. Kidney cortex was used as test tissue, but a few other organs were occasionally used. Thin sections were floated on the surface of several incubation media routinely employed for enzyme cytochemistry. Positive, specific reactions were obtained for alkaline phosphatase in kidney brush border, for adenosine triphosphatase in brush border and in basal membranes of distal tubules, for acid phosphatase and esterase in lysosomes, and for NADH diaphorase in mitochondria. Mitochondrial ATPase was sporadically evident only in the distal tubule of the kidney. Localizations of enzyme activity reported by other technical approaches were confirmed and in some cases somewhat improved.

Mucosal Enzyme Activities, with Special Reference to Enzymes Implicated in Bicarbonate Secretion, in the Duodenum of Rats with Cysteamine-Induced Ulcers

1983 ◽  
Vol 64 (3) ◽  
pp. 341-347 ◽  
Author(s):  
Danny Stiel ◽  
Denver J. Murray ◽  
Timothy J. Peters
Keyword(s):  
Carbonic Anhydrase ◽  
Gastric Acid ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Subcutaneous Administration ◽  
Duodenal Mucosa ◽  
Bicarbonate Secretion ◽  
Biochemical Basis ◽  
Gastric Acid Hypersecretion ◽  
Acid Hypersecretion

1. Duodenal mucosa was collected from control rats and from animals which had received cysteamine, cysteamine plus cimetidine or pentagastrin. Animals which received cysteamine with or without cimetidine developed acute duodenal ulcers. Cysteamine treatment resulted in gastric acid hypersecretion, which was largely abolished by concurrent cimetidine administration. 2. Activities of enzymes implicated in bicarbonate secretion, HCO−3-activated ATPase, carbonic anhydrase and Na+ + K+-activated ATPase, were measured in the duodenal mucosa of control rats and animals 24 h after subcutaneous administration of cysteamine. Assays of these enzymes in duodenal mucosal homogenates from animals with cysteamine-induced ulcers showed significant decreases in HCO−3-activated ATPase and carbonic anhydrase activities compared with controls. 3. Alkaline phosphatase activity also fell significantly in the cysteamine-treated animals, and possibly reflects the HCO−3-activated ATPase activity in the brush-border membrane. in contrast, activities of other marker enzymes from the brush-border membrane and from several intracellular organelles were unchanged, indicating an absence of gross organelle pathology in this experimental model. 4. Similar changes in enzyme activity were not caused by treatment with pentagastrin. Administration of cimetidine with the cysteamine did not protect the animals against ulceration, and the activity of HCO−3-activated ATPase was persistently decreased. However, the carbonic anhydrase activity was unaltered in this latter group, compared with controls. 5. These findings suggest that in cysteamine-induced duodenal ulceration both gastric acid hypersecretion and impaired duodenal resistance occurs. It is suggested that decreased activities of key enzymes implicated in HCO−3 secretion may reflect the biochemical basis for the decreased mucosal resistance.

scholarly journals Characterization and localization of myosin in the brush border of intestinal epithelial cells

1978 ◽  
Vol 79 (2) ◽  
pp. 444-453 ◽  
Author(s):  
MS Mooseker ◽  
TD Pollard
Keyword(s):  
Ionic Strength ◽  
Epithelial Cells ◽  
Atpase Activity ◽  
Brush Border ◽  
Intestinal Epithelial Cells ◽  
Gel Filtration ◽  
Intestinal Epithelial ◽  
Terminal Web ◽  
Brush Borders ◽  
Low Ionic Strength

The brush border of intestinal epithelial cells consists of a tightly packed array of microvilli, each of which contains a core of actin filaments. It has been postulated that microvillar movements are mediated by myosin interactions in the terminal web with the basal ends of these actin cores (Mooseker, M.S. 1976. J. Cell. Biol. 71:417-433). We report here that two predictions of this model are correct: (a) The brush border contains myosin, and (b) myosin is located in the terminal web. Myosin is isolated in 70 percent purity by solubilization of Triton-treated brush borders in 0.6 M KI, and separation of the components by gel filtration. Most of the remaining contaminants can be removed by precipitation of the myosin at low ionic strength. This yield is approximately 1 mg of myosin/30 mg of solubilized brush border protein. The molecule consists of three subunits with molecular weights of 200,000, 19,000, and 17,000 daltons in a 1:1:1 M ratio. At low ionic strength, the myosin forms small, bipolar filaments with dimensions of 300 X 11nm, that are similar to filaments seen previously in the terminal web of isolated brush borders. Like that of other vertebrate, nonmuscle myosins, the ATPase activity of isolated brush border myosin in 0.6 M KCI is highest with EDTA (1 μmol P(i)/mg-min; 37 degrees C), intermediate with Ca++ (0.4 μmol P(i)/mg-min), and low with Mg++ (0.01 μmol P(i)/mg-min). Actin does not stimulate the Mg-ATPase activity of the isolated enzyme. Antibodies against the rod fragment of human platelet myosin cross-react by immunodiffusion with brush border myosin. Staining of isolated mouse or chicken brush borders with rhodamine-antimyosin demonstrates that myosin is localized exclusively in the terminal web.

Scanning Electron Microscopy of Human Jejunum in Whipple's Disease

1977 ◽  
Vol 35 ◽  
pp. 354-355
Author(s):  
John H. L. Watson ◽  
C. N. Sun
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Basement Membrane ◽  
Lamina Propria ◽  
Brush Border ◽  
Whipple’S Disease ◽  
Whipple's Disease ◽  
Biopsy Specimens ◽  
Brush Borders ◽  
Scanning Electron

That the etiology of Whipple's disease could be bacterial was first suggested from electron micrographs in 1960. Evidence for binary fission of the bacteria, their phagocytosis by histiocytes in the lamina propria, their occurrence between and within the cells of the epithelium and on the brush border of the lumen were reported later. Scanning electron microscopy has been applied by us in an attempt to confirm the earlier observations by the new technique and to describe the bacterium further. Both transmission and scanning electron microscopy have been used concurrently to study the same biopsy specimens, and transmission observations have been used to confirm those made by scanning.The locations of the brush borders, the columnar epithelial cells, the basement membrane and the lamina propria beneath it were each easily identified by scanning electron microscopy. The lamina propria was completely filled with the wiener-shaped bacteria, Fig. 1.

scholarly journals A combined microphysiological-computational omics approach in dietary protein evaluation

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Paulus G. M. Jochems ◽  
Willem R. Keusters ◽  
Antoine H. P. America ◽  
Pascale C. S. Rietveld ◽  
Shanna Bastiaan-Net ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Brush Border ◽  
Biological Effects ◽  
Whey Protein Concentrate ◽  
World Population ◽  
Biological Efficacy ◽  
Protein Sources ◽  
Immune Parameters ◽  
Peptide Composition ◽  
Brush Border Enzyme

AbstractFood security is under increased pressure due to the ever-growing world population. To tackle this, alternative protein sources need to be evaluated for nutritional value, which requires information on digesta peptide composition in comparison to established protein sources and coupling to biological parameters. Here, a combined experimental and computational approach is presented, which compared seventeen protein sources with cow’s whey protein concentrate (WPC) as the benchmark. In vitro digestion of proteins was followed by proteomics analysis and statistical model-based clustering. Information on digesta peptide composition resulted in 3 cluster groups, primarily driven by the peptide overlap with the benchmark protein WPC. Functional protein data was then incorporated in the computational model after evaluating the effects of eighteen protein digests on intestinal barrier integrity, viability, brush border enzyme activity, and immune parameters using a bioengineered intestine as microphysiological gut system. This resulted in 6 cluster groups. Biological clustering was driven by viability, brush border enzyme activity, and significant differences in immune parameters. Finally, a combination of proteomic and biological efficacy data resulted in 5 clusters groups, driven by a combination of digesta peptide composition and biological effects. The key finding of our holistic approach is that protein source (animal, plant or alternative derived) is not a driving force behind the delivery of bioactive peptides and their biological efficacy.

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