The Control of Phosphate Uptake by the Isolated Renal Tubule

Understanding of renal function has been facilitated by the technique of perfusion of isolated renal tubule segments in vitro. The basic technology originated in the Laboratory of Kidney and Electrolyte Metabolism of the National Institutes of Health in the early 1960s and then was expanded to apply a variety of analytical methods to single tubules.

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The inhibition of parathyroid-hormone actions on gluconeogenesis and phosphate transport by 3-mercaptopicolinate in rabbit renal proximal tubules

Biochemical Journal ◽

10.1042/bj2330271 ◽

1986 ◽

Vol 233 (1) ◽

pp. 271-273

Author(s):

N Yanagawa ◽

O D Jo

Keyword(s):

Parathyroid Hormone ◽

Phosphoenolpyruvate Carboxykinase ◽

Renal Tubule ◽

Phosphate Transport ◽

Proximal Tubules ◽

Transport Rate ◽

Renal Proximal Tubules ◽

Straight Tubules ◽

Isolated Renal Tubule

By using a glucose microassay and the technique for isolated renal-tubule perfusion in vitro, the addition of 3-mercaptopicolinate, a gluconeogenesis inhibitor which inhibits phosphoenolpyruvate carboxykinase specifically, was found to abolish the effects of parathyroid hormone on gluconeogenesis and phosphate-transport rate in isolated rabbit renal proximal straight tubules, suggesting that these parathyroid-hormone actions may share some unknown, yet 3-mercaptopicolinate-inhibitable, intracellular processes.

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Effect of cystine dimethylester on renal solute handling and isolated renal tubule transport in the rat: A new model of the fanconi syndrome

Metabolism ◽

10.1016/0026-0495(87)90246-0 ◽

1987 ◽

Vol 36 (12) ◽

pp. 1185-1191 ◽

Cited By ~ 30

Author(s):

John W. Foreman ◽

Margaret Ann Bowring ◽

Judithann Lee ◽

Beatrice States ◽

Stanton Segal

Keyword(s):

Fanconi Syndrome ◽

Renal Tubule ◽

New Model ◽

Cystine Dimethylester ◽

Isolated Renal Tubule

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Verification of anoxic phosphate uptake as the main biochemical mechanism of the “dephanox” process

Water Science & Technology ◽

10.2166/wst.1997.0365 ◽

1997 ◽

Vol 35 (10) ◽

pp. 87-94 ◽

Cited By ~ 7

Author(s):

R. Sorm ◽

J. Wanner ◽

R. Saltarelli ◽

G. Bortone ◽

A. Tilche

Keyword(s):

Activated Sludge ◽

Nutrient Removal ◽

Uptake Rate ◽

Phosphate Uptake ◽

Biochemical Mechanism ◽

Batch Experiments ◽

Batch Tests ◽

Genetic Probes ◽

Activated Sludge Systems ◽

Removal System

The phenomenon of anoxic phosphate uptake with simultaneous denitrification was studied. For this purpose kinetic batch tests have been carried out by using the activated sludge samples from three modifications of nutrient removal activated sludge systems: two based on an anaerobic-anoxic-oxic (A2/O) system and a third on an anaerobic-oxic (A/O) system. The results showed significant differences in anoxic phosphate uptake rate between activated sludge which was alternatively exposed to anoxic conditions and activated sludge from the A/O arrangement. These differences were also accompanied by different denitrification rates. Simultaneously with batch experiments the microscopic observation of activated sludge samples was carried out. Neisser and Gram stained samples showed clear differences in shape, size and distribution of polyphosphate accumulating bacteria between A2/O and A/O Processes. Moreover, experiments performed using genetic probes confirmed the differences in microbiological composition of activated sludge samples from different nutrient removal system arrangements.

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Effect of calcium on transport characteristics of cultured proximal renal cells

AJP Renal Physiology ◽

10.1152/ajprenal.1985.249.3.f346 ◽

1985 ◽

Vol 249 (3) ◽

pp. F346-F355

Author(s):

L. M. Sakhrani ◽

N. Tessitore ◽

S. G. Massry

Keyword(s):

Phosphate Uptake ◽

Cytosolic Calcium ◽

Ruthenium Red ◽

Extracellular Calcium ◽

Transport Processes ◽

Renal Cells ◽

Sodium Uptake ◽

Calcium Loading ◽

Sodium Dependent ◽

Acute Changes

We examined the effects of acute changes in extracellular and intracellular calcium on transport processes in primary culture of proximal rabbit renal cells. A change in extracellular calcium from 0 to 3 mM inhibited amiloride-sensitive sodium uptake by 30%, and this effect was maximal at 1 mM calcium. Other polyvalent cations (Mn2+, Mg2+, La3+, and Ba2+) produced quantitatively similar inhibition of amiloride-sensitive sodium uptake compared with calcium. An increase in cytosolic calcium produced by calcium loading (20 mM) or by A23187 (20 microM) resulted in an inhibition of 25-40% of amiloride-sensitive sodium uptake. Moreover, quinidine (10(-4)M) and ruthenium red (3 microM), agents presumed to increase cytosolic calcium, inhibited amiloride-sensitive sodium uptake by 20-60%. Both these agents also inhibited sodium-dependent phosphate uptake by 20% but had no effect on ouabain-sensitive 86Rb+ uptake or on sodium-dependent alpha-methylglucoside uptake. Our data indicate that increases in extracellular calcium inhibit amiloride-sensitive sodium uptake and increases in cytosolic calcium inhibit sodium-dependent phosphate and amiloride-sensitive sodium uptakes. The effect of extracellular calcium may be due to charge screening and/or binding to the negatively charged plasma membrane or due to alterations in membrane fluidity.

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