scholarly journals Transport–dependent cell injury in the S3 segment of the proximal tubule

1986 ◽  
Vol 29 (5) ◽  
pp. 1033-1037 ◽  
Author(s):  
Paul F. Shanley ◽  
Mayer Brezis ◽  
Katherine Spokes ◽  
Patricio Silva ◽  
Franklin H. Epstein ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Cell Injury ◽  
Dependent Cell ◽  
S3 Segment

ATP depletion rather than mitochondrial depolarization mediates hepatocyte killing after metabolic inhibition

1994 ◽  
Vol 267 (1) ◽  
pp. C67-C74 ◽  
Author(s):  
A. L. Nieminen ◽  
A. K. Saylor ◽  
B. Herman ◽  
J. J. Lemasters
Keyword(s):  
Cell Death ◽  
Cell Injury ◽  
Rat Hepatocytes ◽  
Cell Killing ◽  
Atp Depletion ◽  
Mitochondrial Depolarization ◽  
Minimum Concentration ◽  
Atp Formation ◽  
Mitochondrial Atp Synthase ◽  
Dependent Cell

The importance of ATP depletion and mitochondrial depolarization in the toxicity of cyanide, oligomycin, and carbonyl cyanide m-cholorophenylhydrazone (CCCP), an uncoupler, was evaluated in rat hepatocytes. Oligomycin, an inhibitor of the reversible mitochondrial ATP synthase (F1F0-adenosinetriphosphatase), caused dose-dependent cell killing with 0.1 microgram/ml being the minimum concentration causing the maximum cell killing. Oligomycin also caused rapid ATP depletion without causing mitochondrial depolarization. Fructose (20 mM), a potent glycolytic substrate in liver, protected completely against oligomycin toxicity. CCCP (5 microM) also caused rapid killing of hepatocytes. Fructose retarded cell death caused by CCCP but failed to prevent lethal cell injury. Although oligomycin (1.0 microgram/ml) was lethally toxic by itself, in the presence of fructose it protected completely against CCCP-induced cell killing. Cyanide (2.5 mM), an inhibitor of mitochondrial respiration, caused rapid cell killing that was reversed by fructose. CCCP completely blocked fructose protection against cyanide, causing mitochondrial depolarization and rapid ATP depletion. In the presence of fructose and cyanide, oligomycin protected cells against CCCP-induced ATP depletion and cell death but did not prevent mitochondrial depolarization. In every instance, cell killing was associated with ATP depletion, whereas protection against lethal cell injury was associated with preservation of ATP. In conclusion, protection by fructose against toxicity of cyanide, oligomycin, and CCCP was mediated by glycolytic ATP formation rather than by preservation of the mitochondrial membrane potential. These findings support the hypothesis that inhibition of cellular ATP formation is a crucial event in the progression of irreversible cell injury.

Intracellular pH regulation in rabbit S3 proximal tubule: basolateral Cl-HCO3 exchange and Na-HCO3 cotransport

1990 ◽  
Vol 258 (2) ◽  
pp. F371-F381 ◽  
Author(s):  
N. L. Nakhoul ◽  
L. K. Chen ◽  
W. F. Boron
Keyword(s):  
Proximal Tubule ◽  
Intracellular Ph ◽  
Initial Rate ◽  
Ph Regulation ◽  
Basolateral Membrane ◽  
Intracellular Ph Regulation ◽  
S3 Segment ◽  
Absorbance Spectra ◽  
Rule Out

We studied the role of basolateral HCO3- transport in the regulation of intracellular pH (pHi) in the isolated perfused S3 segment of the rabbit proximal tubule. pHi was calculated from absorbance spectra of the pH-sensitive dye dimethylcarboxyfluorescein. Solutions were normally buffered to pH 7.4 at 37 degrees C with 25 mM HCO3- 5% CO2. pHi fell by approximately 0.17 when luminal [HCO3-] was lowered to 5 mM at fixed PCO2 (i.e., reducing pH to 6.8) but by approximately 0.42 when [HCO3-] in the bath (i.e., basolateral solution) was lowered to 5 mM. The pHi decrease elicited by reducing bath [HCO3-] was substantially reduced by removal of Cl- or Na+, suggesting that components of basolateral HCO3- transport are Cl- and/or Na+ dependent. We tested for the presence of basolateral Cl-HCO3 exchange by removing bath Cl-. This caused pHi to increase by approximately 0.23, with an initial rate of approximately 100 X 10(-4) pH/s. Although the initial rate of this pHi increase was not reduced by removing Na+ bilaterally, it was substantially lowered by the nominal removal of HCO3- from bath and lumen or by the addition of 0.1 mM 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS) to the bath. The results thus suggest that a Na-independent Cl-HCO3 exchanger is present at the basolateral membrane. We tested for the presence of basolateral Na-HCO3 cotransport by removing bath Na+. This caused pHi to fall reversibly by approximately 0.26 with initial rates of pHi decline and recovery being approximately 30 and approximately 41 X 10(-4) pH/s, respectively. Although the bilateral removal of Cl- had no effect on these rates, the nominal removal of HCO3- or the presence of DIDS substantially slowed the pHi changes. Thus, in addition to a Cl-HCO3 exchanger, the basolateral membrane of the S3 proximal tubule also appears to possess a Na-HCO3 cotransport mechanism. The data do not rule out the possibility of other basolateral HCO3- transporters.

Effects of acetate on luminal acidification processes in the S3 segment of the rabbit proximal tubule

1989 ◽  
Vol 257 (4) ◽  
pp. F586-F594 ◽  
Author(s):  
J. Geibel ◽  
G. Giebisch ◽  
W. F. Boron
Keyword(s):  
Acid Secretion ◽  
Proximal Tubule ◽  
S3 Segment ◽  
Presence And Absence

We determined that, in the nominal absence of HCO-3, acetate (Ac-) doubles luminal acidification in the S3 segment of the rabbit proximal tubule. This stimulation had two components, one that was dependent on Na+ and luminal Ac- and a second that was independent of Na+ but dependent on basolateral Ac-. In the presence of 25 mM HCO-3, Ac- did not stimulate acid secretion (i.e., HCO-3 reabsorption), but actually inhibited it. The inhibition was 35% with bilateral Ac- and 15% with basolateral Ac-. The effects of Ac- were reversible both in the absence and presence of HCO-3, and are present at concentrations as low as 1 mM. We conclude that acetate (i.e., monocarboxylates) has a significant effect on luminal acidification processes both in the presence and absence of HCO-3.

ER stress contributes to renal proximal tubule injury by increasing SREBP-2-mediated lipid accumulation and apoptotic cell death

2012 ◽  
Vol 303 (2) ◽  
pp. F266-F278 ◽  
Author(s):  
Šárka Lhoták ◽  
Sudesh Sood ◽  
Elise Brimble ◽  
Rachel E. Carlisle ◽  
Stephen M. Colgan ◽  
...  
Keyword(s):  
Er Stress ◽  
Proximal Tubule ◽  
Lipid Accumulation ◽  
Cell Injury ◽  
Apoptotic Cell ◽  
Renal Proximal Tubule ◽  
Proximal Tubule Cell ◽  
Tubule Cell ◽  
Proximal Tubule Cells ◽  
Tubule Cells

Renal proximal tubule injury is induced by agents/conditions known to cause endoplasmic reticulum (ER) stress, including cyclosporine A (CsA), an immunosuppressant drug with nephrotoxic effects. However, the underlying mechanism by which ER stress contributes to proximal tubule cell injury is not well understood. In this study, we report lipid accumulation, sterol regulatory element-binding protein-2 (SREBP-2) expression, and ER stress in proximal tubules of kidneys from mice treated with the classic ER stressor tunicamycin (Tm) or in human renal biopsy specimens showing CsA-induced nephrotoxicity. Colocalization of ER stress markers [78-kDa glucose regulated protein (GRP78), CHOP] with SREBP-2 expression and lipid accumulation was prominent within the proximal tubule cells exposed to Tm or CsA. Prolonged ER stress resulted in increased apoptotic cell death of lipid-enriched proximal tubule cells with colocalization of GRP78, SREBP-2, and Ca2+-independent phospholipase A2 (iPLA2β), an SREBP-2 inducible gene with proapoptotic characteristics. In cultured HK-2 human proximal tubule cells, CsA- and Tm-induced ER stress caused lipid accumulation and SREBP-2 activation. Furthermore, overexpression of SREBP-2 or activation of endogenous SREBP-2 in HK-2 cells stimulated apoptosis. Inhibition of SREBP-2 activation with the site-1-serine protease inhibitor AEBSF prevented ER stress-induced lipid accumulation and apoptosis. Overexpression of the ER-resident chaperone GRP78 attenuated ER stress and inhibited CsA-induced SREBP-2 expression and lipid accumulation. In summary, our findings suggest that ER stress-induced SREBP-2 activation contributes to renal proximal tubule cell injury by dysregulating lipid homeostasis.

Intestinal-type alkaline phosphatase in urine as an indicator of mercury induced effects on the S3 segment of the proximal tubule

1992 ◽  
Vol 7 (3) ◽  
pp. 225-229 ◽  
Author(s):  
G. D. Nuyts ◽  
H. A. Roels ◽  
G. F. Verpooten ◽  
A. M. Bernard ◽  
R. R. Lauwerys ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Proximal Tubule ◽  
Intestinal Type ◽  
S3 Segment

scholarly journals Regulation of the taurine transporter gene in the S3 segment of the proximal tubule

1997 ◽  
Vol 52 (3) ◽  
pp. 748-754 ◽  
Author(s):  
Douglas G. Matsell ◽  
Tracey Bennett ◽  
Xiaobin Han ◽  
Andrea M. Budreau ◽  
Russell W. Chesney
Keyword(s):  
Proximal Tubule ◽  
Transporter Gene ◽  
Taurine Transporter ◽  
S3 Segment

Direct toxic effect of the radiocontrast agent diatrizoate on renal proximal tubule cells

1987 ◽  
Vol 252 (2) ◽  
pp. F246-F255 ◽  
Author(s):  
H. D. Humes ◽  
D. A. Hunt ◽  
M. D. White
Keyword(s):  
Cell Viability ◽  
Proximal Tubule ◽  
Toxic Effect ◽  
Cell Injury ◽  
Renal Tubule ◽  
Metabolic Parameters ◽  
Proximal Tubule Cells ◽  
Radiocontrast Agent ◽  
Tubule Cells ◽  
Renal Proximal Tubule Cells

The pathophysiology of radiocontrast agent-induced acute renal failure is presently unclear. To test for a possible direct deleterious effect of diatrizoate, a commonly used radiocontrast agent, on renal tubule cells, suspensions enriched in rabbit proximal tubule segments were incubated with sodium diatrizoate. After these manipulations, a variety of well-established metabolic parameters to quantitate the extent of cell injury were measured. Diatrizoate sodium (25 mM) produced significant declines in tubule K+, ATP, and total adenine nucleotide (TAN) contents, significant decreases in tubule basal and uncoupled respiratory rates, and a significant increase in tubule Ca2+ content, demonstrating the development of cell injury induced by diatrizoate. These effects were dose related and were progressive with increasing incubation time from 97.5 to 157.5 min. The effects of N-methylglucosamine (meglumine) on renal tubule cell viability was also evaluated. Meglumine is a low molecular weight amino-substituted cationic compound and is commonly added to radiocontrast dye solutions. Meglumine (25 mM) had significant effects to lower tubule K+ content and to decrease both tubule basal and uncoupled respiratory rates. These alterations were slightly additive to diatrizoate in that meglumine diatrizoate produced greater alterations in tubule-metabolic parameters compared to diatrizoate sodium. A period of 22.5 min of hypoxia also caused deleterious changes in each of these quantitative indices of cell viability, and diatrizoate potentiated the degree of hypoxia-induced cell injury. These results demonstrate that the radiocontrast agent, diatrizoate, is directly toxic to renal proximal tubule cells. Meglumine, a cation added to diatrizoate containing radiocontrast solutions, also had a moderate toxic effect on renal epithelial cells and added to the toxicity of diatrizoate. Diatrizoate also aggravated the degree of cell injury induced by a 22.5-min period of hypoxia. These experiments thus provide evidence for a direct toxic effect of diatrizoate on proximal renal tubule cells which was additive to hypoxic cell injury.

Ca2+ uptake, fatty acid, and LDH release during proximal tubule hypoxia: effects of mepacrine and dibucaine

1994 ◽  
Vol 266 (2) ◽  
pp. F196-F201 ◽  
Author(s):  
D. Bunnachak ◽  
A. R. Almeida ◽  
J. F. Wetzels ◽  
P. Gengaro ◽  
R. A. Nemenoff ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Lactate Dehydrogenase ◽  
Proximal Tubule ◽  
Uptake Rate ◽  
Cell Injury ◽  
Potential Effect ◽  
Proximal Tubules ◽  
Membrane Injury ◽  
Ldh Release ◽  
Higher Doses

In freshly isolated hypoxic rat proximal tubules, Ca2+ uptake rate increases promptly, within 1 min, and remains significantly elevated throughout a 20-min period of hypoxia. Lactate dehydrogenase (LDH) release, a sign of membrane injury, increases only after 5 min of hypoxia and thereafter rises progressively. The potential effect of increased Ca2+ uptake rate to activate phospholipases, which would then initiate membrane injury, was evaluated by treating hypoxic tubules with three dissimilar phospholipase inhibitors, i.e., mepacrine, dibucaine, or p-bromophenacyl bromide (PBPB). LDH release averaged 11.9 and 13.8% after 10 and 20 min of normoxia, respectively. With 10 or 20 min of hypoxia LDH release increased to 46.0 and 65.2%, respectively (P < 0.01), and Ca2+ uptake rate increased from 2.56 in normoxia to 4.71 nmol.mg-1 x min-1 at 10 min of hypoxia (P < 0.01) and from 2.82 in normoxia to 3.76 nmol/mg at 20 min of hypoxia (P < 0.05). In a separate series of tubules, after 10 min of hypoxia LDH release was reduced by pretreatment with 50 microM mepacrine (66.1 to 47.3%, P < 0.01) or 50 microM dibucaine (53.1 to 38.5%, P < 0.02). The increase in Ca2+ uptake rate also was significantly reduced. After 20 min of hypoxia neither mepacrine nor dibucaine reduced Ca2+ uptake rate; LDH release was modestly reduced by dibucaine but not mepacrine. Higher doses of mepacrine (500 microM) and dibucaine (250 microM) also reduced cell injury at 10 min of hypoxia as assessed by LDH release.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Effect of basolateral CO2/HCO3- on intracellular pH regulation in the rabbit S3 proximal tubule.

1993 ◽  
Vol 102 (6) ◽  
pp. 1171-1205 ◽  
Author(s):  
N L Nakhoul ◽  
L K Chen ◽  
W F Boron
Keyword(s):  
Steady State ◽  
Proximal Tubule ◽  
Intracellular Ph ◽  
Ph Regulation ◽  
Uptake Mechanism ◽  
Luminal Membrane ◽  
S3 Segment ◽  
Acid Extrusion ◽  
Acid Loading

We used the absorbance spectrum of the pH-sensitive dye dimethylcarboxyfluorescein to monitor intracellular pH (pHi) in the isolated perfused S3 segment of the rabbit proximal tubule, and examined the effect on pHi of switching from a HEPES to a CO2/HCO3- buffer in the lumen and/or the bath (i.e., basolateral solution). Solutions were titrated to pH 7.40 at 37 degrees C. With 10 mM acetate present bilaterally (lumen and bath), this causing steady-state pHi to be rather high (approximately 7.45), bilaterally switching the buffer from 32 mM HEPES to 5% CO2/25 mM HCO3- caused a sustained fall in pHi of approximately 0.26. However, with acetate absent bilaterally, this causing steady-state pHi to be substantially lower (approximately 6.9), bilaterally switching to CO2/HCO3- caused a transient pHi fall (due to the influx of CO2), followed by a sustained rise to a level approximately 0.18 higher than the initial one. The remainder of the experiments was devoted to examining this alkalinization in the absence of acetate. Switching to CO2/HCO3- only in the lumen caused a sustained pHi fall of approximately 0.15, whereas switching to CO2/HCO3- only in the bath caused a transient fall followed by a sustained pHi increase to approximately 0.26 above the initial value. This basolateral CO2/HCO3(-)-induced alkalinization was not inhibited by 50 microM DIDS applied shortly after CO2/HCO3- washout, but was slowed approximately 73% by DIDS applied more than 30 min after CO2/HCO3- washout. The rate was unaffected by 100 microM bilateral acetazolamide, although this drug greatly reduced CO2-induced pHi transients. The alkalinization was not blocked by bilateral removal of Na+ per se, but was abolished at pHi values below approximately 6.5. The alkalinization was also unaffected by short-term bilateral removal of Cl- or SO4=. Basolateral CO2/HCO3- elicited the usual pHi increase even when all solutes were replaced, short or long-term (&gt; 45 min), by N-methyl-D-glucammonium/glucuronate (NMDG+/Glr-). Luminal CO2/HCO3- did not elicit a pHi increase in NMDG+/Glr-. Although the sustained pHi increase elicited by basolateral CO2/HCO3- could be due to a basolateral HCO3- uptake mechanism, net reabsorption of HCO3- by the S3 segment, as well as our ACZ data, suggest instead that basolateral CO2/HCO3- elicits the sustained pHi increase either by inhibiting an acid-loading process or stimulating acid extrusion across the luminal membrane (e.g., via an H+ pump).

Contribution of actin cytoskeletal alterations to ATP depletion and calcium-induced proximal tubule cell injury

1996 ◽  
Vol 270 (1) ◽  
pp. F39-F52 ◽  
Author(s):  
S. Nurko ◽  
K. Sogabe ◽  
J. A. Davis ◽  
N. F. Roeser ◽  
M. Defrain ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Proximal Tubule ◽  
Laser Scanning ◽  
Structural Changes ◽  
Cell Injury ◽  
Membrane Damage ◽  
Atp Depletion ◽  
Similar Proportion ◽  
Proximal Tubule Cell ◽  
Tubule Cell

The actin cytoskeleton of rabbit proximal tubules was assessed by deoxyribonuclease (DNase) binding, sedimentability of detergent-insoluble actin, laser-scanning confocal microscopy, and ultrastructure during exposure to hypoxia, antimycin, or antimycin plus ionomycin. One-third of total actin was DNase reactive in control cells prior to deliberate depolymerization, and a similar proportion was unsedimentable from detergent lysates during 2.5 h at 100,000 g. Tubules injured by hypoxia or antimycin alone, without glycine, showed Ca(2+)-dependent pathology of the cytoskeleton, consisting of increases in DNase-reactive actin, redistribution of pelletable actin, and loss of microvilli concurrent with lethal membrane damage. In contrast, tubules similarly depleted of ATP and incubated with glycine showed no significant changes of DNase-reactive actin or actin sedimentability for up to 60 min, but, nevertheless, developed substantial loss of basal membrane-associated actin within 15 min and disruption of actin cores and clubbing of microvilli at durations > 30 min. These structural changes that occurred in the presence of glycine were not prevented by limiting Ca2+ availability or pH 6.9. Very rapid and extensive cytoskeletal disruption followed antimycin-plus-ionomycin treatment. In this setting, glycine and pH 6.9 decreased lethal membrane damage but did not ameliorate pathology in the cytoskeleton or microvilli; limiting Ca2+ availability partially protected the cytoskeleton but did not prevent lethal membrane damage. The data suggest that both ATP depletion-dependent but Ca(2+)-independent, as well as Ca(2+)-mediated, processes can disrupt the actin cytoskeleton during acute proximal tubule cell injury; that both types of change occur, despite protection afforded by glycine and reduced pH against lethal membrane damage; and that Ca(2+)-independent processes primarily account for prelethal actin cytoskeletal alterations during simple ATP depletion of proximal tubule cells.

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