Effect of a Single Test Dose of Lithium on Renal Proximal Tubular Function

Abstract Urinary excretion of beta 2-microglobulin (beta 2M) is a widely used test of renal proximal tubular function. beta 2M is known to be unstable in normal urine with a pH less than 5.5. The results of a study of beta 2M excretion in patients receiving gentamicin suggested that beta 2M might be more unstable in pathological urine. A series of experiments was designed to define the extent, variability, and mechanism of its instability in pathological urine. It was unstable in pathological urine with a pH of 6.0 at 37 degrees C and pH 5.5 at room temperature, but this varied in urines from different patients. The instability was abolished by heating the urine to 80 degrees C. These results suggest that the most likely explanation for the instability is enzymic degradation. Because enzymuria will vary among patients, investigators should test the stability of beta 2M in urine from the patients they wish to study before trying to define conditions for urine collection.

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Gluconeogenic renal epithelial cells in tissue culture: an in vitro-model to study normal and impaired renal proximal tubular function

Ersatz- und Ergänzungsmethoden zu Tierversuchen - Forschung ohne Tierversuche 1997 ◽

10.1007/978-3-7091-7500-2_44 ◽

1998 ◽

pp. 264-265

Author(s):

G. Gstraunthaler ◽

E. Troppmair ◽

E. Feifel ◽

W. Pfaller

Keyword(s):

Tissue Culture ◽

Epithelial Cells ◽

In Vitro Model ◽

Renal Epithelial Cells ◽

Proximal Tubular ◽

Vitro Model ◽

Proximal Tubular Function ◽

Renal Proximal Tubular ◽

Renal Proximal Tubular Function

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Erythrocyte Sodium/Lithium Countertransport and Renal Lithium Clearance in a Random Sample of Untreated Middle-Aged Men

Clinical Science ◽

10.1042/cs0770337 ◽

1989 ◽

Vol 77 (3) ◽

pp. 337-342 ◽

Cited By ~ 12

Author(s):

Pasquale Strazzullo ◽

Francesco P. Cappuccio ◽

Maurizio Trevisan ◽

Licia Iacoviello ◽

Roberto Iacone ◽

...

Keyword(s):

Blood Pressure ◽

Fractional Excretion ◽

Tubular Function ◽

Proximal Tubular ◽

Erythrocyte Sodium ◽

Proximal Tubular Function ◽

Renal Proximal Tubular ◽

Relationship Of ◽

The Relationship ◽

Male Subjects

1. It has been proposed that the enhanced erythrocyte Na+/Li+ countertransport observed in many patients with essential hypertension could be a marker of abnormal renal proximal tubular function. We thus investigated the relationship of blood pressure and Na+/Li+ countertransport to an index of proximal tubular function such as renal Li+ clearance. 2. The study was carried out in a sample of 299 untreated male subjects (aged 21–59 years) randomly selected from a population at work. Na+/Li+ counter-transport was measured in a representative sub-group of 176 men. 3. We did not detect statistically significant correlation of either blood pressure or Na+/Li+ countertransport (Vmax) with fractional excretion of Li+, while confirming the existence of a significant continuous association of blood pressure and body mass index with Na+/Li+ countertransport (P < 0.01). 4. A sub-sample of 57 participants belonging to the lowest or the highest quintiles of Na+/Li+ counter-transport distribution repeated the Li+ clearance study after moderate Na+ restriction. 5. Although fractional excretions of Na+ and Li+ were reduced on the low Na+ diet (both P < 0.001), they did not differ significantly between groups. 6. Our results are at variance with the findings of a recent case-control study in a young age group and suggest that further studies are necessary before a conclusion can be drawn as to the suitability of Na+/Li+ countertransport as a marker of Na+ reabsorption in the renal proximal tubule.

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The possible involvement of calcium in renal proximal tubular reabsorptive defect in the rat after release of ureteral obstruction

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y90-100 ◽

1990 ◽

Vol 68 (6) ◽

pp. 667-670

Author(s):

V. Chatsudthipong ◽

S. Sophasan ◽

S. Jariyawat

Keyword(s):

Ureteral Obstruction ◽

Tubular Function ◽

Free Calcium ◽

Cytosolic Free Calcium ◽

Control Value ◽

Proximal Tubular ◽

Tubular Functions ◽

Proximal Tubular Function ◽

Renal Proximal Tubular ◽

Renal Tubular

The temporal relationship between changes in cytosolic free calcium and proximal tubular function was examined in rats following 24 h of unilateral and bilateral ureteral obstruction. Immediately after release of unilateral ureteral obstruction, proximal tubular functions were found to be normal. Cytosolic free calcium in isolated proximal tubules of the ureteral obstructed and contralateral kidneys were 160 ± 8 and 172 ± 15 nM, respectively. On the 7th day after release, cytosolic free calcium was not different from the sham control value (135 ± 6 vs. 149 ± 7 nM). In contrast, immediately after release of bilateral ureteral obstruction, cytosolic free calcium was increased significantly to 219 ± 6 from 139 ± 9 nM in sham-operated controls. Subsequent declines in cytosolic free calcium to 196 ± 15 and 148 ± 7 nM were observed at 3 and 7 days after release of bilateral ureteral obstruction, respectively. Over this period, renal tubular functions gradually returned to normal. Changes in cytosolic free calcium correlate well with the reported improvement in renal tubular function after release of bilateral ureteral obstruction. Therefore, one possible mechanism for the impairment of tubular function observed in bilateral ureteral obstruction may be an increase in cytosolic free calcium.Key words: ureteral obstruction, cytosolic free calcium, renal proximal tubule, rat.

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