Factors affecting the ratio of different organic osmolytes in renal medullary cells

1990 ◽  
Vol 259 (5) ◽  
pp. F847-F858 ◽  
Author(s):  
T. Moriyama ◽  
A. Garcia-Perez ◽  
M. B. Burg
Keyword(s):  
Tissue Culture ◽  
Aldose Reductase ◽  
Glucose Concentration ◽  
Reductase Activity ◽  
Renal Medulla ◽  
Organic Osmolytes ◽  
Factors Affecting ◽  
High Concentrations ◽  
Medullary Cells

Renal medullary cells contain high concentrations of sorbitol, inositol, glycerophosphorylcholine (GPC), and betaine, which balance the variably high osmolality of extracellular NaCl. We found that PAP-HT25 (rabbit renal medullary) cells in tissue culture increase their content of all four when medium osmolality is increased by adding NaCl and urea. However, this requires that betaine be added to medium in addition to customary constituents. Some factors affecting the mix of organic osmolytes in these cells during hypertonicity are as follows. 1) Urea in medium increases cell GPC and tends to decrease others, particularly betaine. 2) With small increases in medium NaCl, intracellular inositol is highest, whereas sorbitol predominates with large NaCl increases. 3) When osmolality is suddenly decreased, these four organic osmolytes exit rapidly from cells, but in differing relative amounts (betaine much greater than sorbitol greater than inositol much greater than GPC). 4) Altering cell betaine levels (by varying betaine in medium) causes reciprocal changes in cell sorbitol (by affecting aldose reductase activity) and vice versa, whereas inositol and GPC are less affected. 5) Raising medium glucose concentration (from which sorbitol is synthesized) increases cell sorbitol and decreases cell inositol and betaine. 6) Decreasing the amount of GPC in cells (by removing choline from medium) causes small changes in betaine and sorbitol, but not in inositol. Changing the amount of inositol does not affect the others. Similar interrelations may operate in vivo to vary the mix of organic osmolytes in renal medulla.

Intracellular betaine substitutes for sorbitol in protecting renal medullary cells from hypertonicity

1991 ◽  
Vol 260 (4) ◽  
pp. F494-F497 ◽  
Author(s):  
T. Moriyama ◽  
A. Garcia-Perez ◽  
A. D. Olson ◽  
M. B. Burg
Keyword(s):  
Aldose Reductase ◽  
Reductase Activity ◽  
Organic Osmolytes ◽  
Cloning Efficiency ◽  
Hypertonic Medium ◽  
Aldose Reductase Inhibitors ◽  
Reductase Inhibitors ◽  
Nacl Concentration ◽  
Medullary Cells

Renal medullary cells are normally exposed to a variably high extracellular NaCl concentration. They compensate by accumulating large amounts of organic osmolytes, including sorbitol and betaine. The sorbitol is synthesized from glucose, catalyzed by aldose reductase. Previously, inhibition of aldose reductase activity was noted to greatly reduce renal medullary cell survival and growth (measured by cloning efficiency) in tissue cultures of renal medullary cells in hypertonic medium. In contrast, inhibition of aldose reductase and renal medullary sorbitol accumulation is not associated with kidney damage in vivo. In the present experiments we find that addition of betaine to the medium, and its resultant uptake by the cells, largely replaces the decrease in sorbitol caused by aldose reductase inhibitors and restores the cloning efficiency. We presume that in vivo uptake of betaine by renal medullary cells similarly protects them from harm when aldose reductase inhibitors lower sorbitol. The results also demonstrate that one organic osmolyte can substitute for another in protecting cells from hypertonicity, consistent with the compatible osmolytes hypothesis.

Renal medullary organic osmolytes

1991 ◽  
Vol 71 (4) ◽  
pp. 1081-1115 ◽  
Author(s):  
A. Garcia-Perez ◽  
M. B. Burg
Keyword(s):  
Aldose Reductase ◽  
Renal Medulla ◽  
Organic Osmolytes ◽  
Organic Osmolyte ◽  
Concentrating Mechanism ◽  
Nacl Concentration ◽  
Survival And Growth ◽  
Harmful Effects ◽  
Medullary Cells

Sorbitol, inositol, GPC, and betaine are the predominant organic osmolytes in renal medullary cells. They protect the cells from harmful effects of the high interstitial NaCl and urea concentrations that occur normally in the renal medulla with operation of the urinary concentrating mechanism. Their levels correlate with extracellular NaCl concentration and, in the case of GPC, also with urea. Sorbitol is synthesized from glucose in a reaction catalyzed by aldose reductase. Inositol and betaine are transported into the cell. Glycerophosphorylcholine synthesis is dependent on choline. The transcription of aldose reductase and the transport of betaine and inositol are regulated, dependent on the degree of hypertonicity. Normal organic osmolyte regulation contributes to the survival and growth of medullary cells in their hyperosmolal environment, and defective regulation can damage them.

Urea and methylamines have similar effects on aldose reductase activity

1997 ◽  
Vol 273 (6) ◽  
pp. F1048-F1053 ◽  
Author(s):  
Maurice B. Burg ◽  
Eugenia M. Peters
Keyword(s):  
Aldose Reductase ◽  
Reductase Activity ◽  
Maximum Velocity ◽  
Renal Medulla ◽  
Biological Macromolecules ◽  
Organic Osmolytes ◽  
Inhibitory Effects ◽  
High Concentration ◽  
Apparent Contradiction ◽  
And Function

The concentration of urea in renal medullary cells is sufficiently high to inhibit activity of many enzymes, yet the cells survive and function. The generally accepted explanation is the counteracting osmolytes hypothesis, which holds that methylamines, such as glycerophosphorylcholine (GPC) and glycine betaine (betaine), found in the renal medulla stabilize biological macromolecules and oppose the effects of urea. The present study tests this hypothesis by determining the effects of urea and methylamines, singly and in combination, on the activity of aldose reductase, an enzyme that is important in renal medullas for catalyzing production of sorbitol from glucose. In apparent contradiction to the counteracting osmolytes hypothesis, urea (1.0 M) and three different methylamines (trimethylamine N-oxide, betaine, and GPC; 0.5 M) all have similar and partially additive inhibitory effects. They all decrease substantially both the Michaelis constant ( K m) and the maximum velocity ( V max). Also, a high concentration (0.5 M) of other organic osmolytes that are abundant in the renal medulla, namely inositol, sorbitol, or taurine, has a similar but lesser effect. KCl (0.3 M) causes a small increase in activity. We discuss the significance of these findings with regard to function of aldose reductase in the renal medulla and the counteracting osmolytes hypothesis.

Motility of the Limulus blood cell

1979 ◽  
Vol 37 (1) ◽  
pp. 169-180
Author(s):  
P.B. Armstrong
Keyword(s):  
Tissue Culture ◽  
Time Lapse ◽  
Coelomic Fluid ◽  
Cellular Motility ◽  
Paraffin Oil ◽  
Motile Cells ◽  
Direct Microscopic Examination ◽  
High Concentrations ◽  
Glass Surfaces

The sole cell type (the amoebocyte) found in the coelomic fluid of the horseshoe crab, Limulus polyphemus can be stimulated to become motile by extravasation or trauma. Motility was studied using time-lapse microcinematography and direct microscopic examination of cells in tissue culture and in gill leaflets isolated from young animals. Phase-contrast and Nomarski differential-interference contrast optics were employed. Both in culture and in the gills, motile cells showed 2 interconvertible morphological types: the contracted cell, which was compact and rounded and had a relatively small area of contact with the substratum, and a flattened from with a larger area of contact. In both morphological types, motility involved the protrusion of hyaline pseudopods followed by flow of granular endoplasm forward in the pseudoplod. Cellular motility in vivo (in the gill leaflet) was morphologically identical to that displayed in tissue culture. In culture, motility was unaffected by the nature of the substratum: cells were indistinguishable on fluid (paraffin oil) or solid (glass) substrata or on hydrophobic (paraffin oil, siliconized glass) or hydrophilic (clean glass) surfaces. Cells migrated and spread on agar surfaces. Cell motility was unaffected by high concentrations (100 micrograms/ml) of the microtubule-depolymerizing agent colcemid and was abolished by cytochalasin B at 1 microgram/ml.

scholarly journals Reverse Docking, Molecular Docking, Absorption, Distribution, and Toxicity Prediction of Artemisinin as an Anti-diabetic Candidate

Molekul ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 88
Author(s):  
Ruswanto Ruswanto ◽  
Richa Mardianingrum ◽  
Siswandono Siswandono ◽  
Dini Kesuma
Keyword(s):  
Molecular Docking ◽  
Aldose Reductase ◽  
Glucose Concentration ◽  
In Silico ◽  
Reductase Activity ◽  
Polyol Pathway ◽  
Toxicity Prediction ◽  
In Silico Studies

Aldose reductase is an enzyme that catalyzes one of the steps in the sorbitol (polyol) pathway that is responsible for fructose formation from glucose. In diabetes, aldose reductase activity increases as the glucose concentration increases. The purpose of this research was to identify and develop the use of artemisinin as an anti-diabetic candidate through in silico studies, including reverse docking, receptor analysis, molecular docking, drug scan, absorption, and distributions and toxicity prediction of artemisinin. Based on the results, we conclude that artemisinin can be used as an anti-diabetic candidate through inhibition of aldose reductase

Osmotic adaptation of renal medullary cells during transition from chronic diuresis to antidiuresis

1993 ◽  
Vol 264 (4) ◽  
pp. F722-F729 ◽  
Author(s):  
M. Sone ◽  
G. J. Albrecht ◽  
A. Dorge ◽  
K. Thurau ◽  
F. X. Beck
Keyword(s):  
Amino Acids ◽  
High Performance ◽  
Renal Medulla ◽  
Organic Osmolytes ◽  
Osmotic Adaptation ◽  
High Concentrations ◽  
Amino Acid Contents ◽  
Tissue Contents ◽  
Abrupt Rise

The cells of the renal medulla adapt osmotically to high extracellular tonicities by high concentrations of organic osmolytes. Intracellular accumulation of these substances is, however, relatively slow. The aim of the present study was to assess the effect of an abrupt rise in extracellular tonicity on intracellular osmotically active substances after prior reduction of medullary contents of organic osmolytes by chronic diuresis. Intra- and extracellular electrolyte concentrations at the papillary tip and the tissue contents of methylamines (glycerophosphorylcholine, betaine), polyols (myo-inositol, sorbitol), and several amino acids were determined in the different kidney zones by electron microprobe analysis and high-performance liquid chromatography in control animals, in rats infused for 6 days with furosemide via osmotic minipumps, and in rats given the vasopressin analogue [deamino-Cys1,D-Arg8]vasopressin (DDAVP) after the chronic furosemide treatment. Chronic diuresis greatly reduced interstitial tonicity and inner medullary contents of methylamines and polyols and moderately reduced inner medullary amino acid contents but did not significantly affect intracellular electrolyte concentrations. When the diuretic rats were infused with DDAVP for 2 h, interstitial tonicity more than doubled and intracellular K and Cl concentrations rose by approximately 60 and 160%, while inner medullary contents of methylamines, polyols, and amino acids were not changed significantly. These data demonstrate that after effective depletion of medullary organic osmolytes by long-term diuresis, the cells of the renal papilla adapt osmotically to an abrupt increase in extracellular tonicities by elevated cell electrolyte concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Effects of growth retarding compounds on chlorophyll accumulation and nitrate reductase activity in nitrate induced cucumber cotyledons

2015 ◽  
Vol 42 (3) ◽  
pp. 431-439 ◽  
Author(s):  
J. S. Knypl
Keyword(s):  
Nitrate Reductase ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Chlorophyll Synthesis ◽  
Growth Retardants ◽  
Chlorophyll Accumulation ◽  
High Concentrations ◽  
Amo 1618 ◽  
Nr Activity

Cotyledons were excised from 5-day old etiolated cucumber seedlings and .grown for 24 or 48 h in solutions of plant growth retardants: AMO-1618,B-Nine, CCC and phosfon D, supplemented with KNO<sub>3</sub> (10<sup>-2</sup>M) in light. Nitrate reductase (NR) activity was determined <i>in vivo</i>. CCC and Phosfon D at high concentrations had no effect on nitrate reductase activity in 24 h tests. CCC at 5xl0<sup>-2</sup> M enhanced NR activity in longer 48 h tests; Phosfon D was inhibitory in that case. AMO-1618 markedly decreased NR activity. B-Nine strikingly enhanced NR activity in KNO<sub>3</sub> induced cytoledons; the effect was positively correlated with the concentration of B-Nine. Ali the compounds inhibited chlorophyll synthesis.

Osmoregulation by slow changes in aldose reductase and rapid changes in sorbitol flux

1988 ◽  
Vol 254 (6) ◽  
pp. C788-C792 ◽  
Author(s):  
S. M. Bagnasco ◽  
H. R. Murphy ◽  
J. J. Bedford ◽  
M. B. Burg
Keyword(s):  
Epithelial Cells ◽  
Aldose Reductase ◽  
Cell Protein ◽  
Organic Osmolytes ◽  
Continuous Line ◽  
Nacl Concentration ◽  
Rapid Changes ◽  
Low Levels ◽  
Medullary Cells ◽  
In Cells

Renal medullary extracellular NaCl concentration is high during antidiuresis. To compensate, the cells accumulate large amounts of nonperturbing, osmotically active solutes (organic “osmolytes”), including sorbitol. GRB-PAP1 is a continuous line of epithelial cells from rabbit inner medulla. These cells accumulate sorbitol when medium NaCl concentration is elevated. The accumulation involves increase in aldose reductase, which catalyzes production of sorbitol from glucose. The purpose of the present study was to investigate control of cell sorbitol once aldose reductase was induced. We measured cell sorbitol, cell-to-medium sorbitol flux, and aldose reductase in cells grown in medium made hyperosmotic (600 mosmol/kg) with added NaCl and at intervals after medium osmolality was reduced to 300 mosmol/kg. In the hyperosmotic medium, cell sorbitol averaged 990 mmol/kg protein (approximately 260 mM), and its flux into the medium was 740 mmol.kg cell protein-1.day-1 (permeability less than 2 X 10(-9) cm/s). Within 5 min after return to isosmotic medium, sorbitol efflux increased greater than 150-fold. By the end of 1 day, cell sorbitol fell 77% but aldose reductase decreased only 10%. Aldose reductase then fell slowly to low levels over 2 wk. Thus renal medullary cells, chronically adapted to high NaCl, reduced their sorbitol level on return to isosmotic conditions by at least two mechanisms: 1) rapid increase in sorbitol flux into the medium, and 2) slow changes in the amount of aldose reductase.

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