Microelectrode Measurement of Cytosol pH of Rat Proximal Tubule Cells in Situ: Control Observations and Effect of Acetazolamide

1985 ◽  
Vol 69 (s12) ◽  
pp. 48P-48P
Author(s):  
R.M. Henderson ◽  
P.B. Bell ◽  
R.D. Cohen ◽  
C. Browning ◽  
R.A. Iles
Keyword(s):  
Proximal Tubule ◽  
Proximal Tubule Cells ◽  
In Situ Control ◽  
Tubule Cells ◽  
Cytosol Ph ◽  
Rat Proximal Tubule

scholarly journals Expression and role of serum and glucocorticoid-regulated kinase 2 in the regulation of Na+/H+ exchanger 3 in the mammalian kidney

2010 ◽  
Vol 299 (6) ◽  
pp. F1496-F1506 ◽  
Author(s):  
Alan C. Pao ◽  
Aditi Bhargava ◽  
Francesca Di Sole ◽  
Raymond Quigley ◽  
Xinli Shao ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Proximal Tubule ◽  
Cell Surface Expression ◽  
Thick Ascending Limb ◽  
Proximal Tubule Cells ◽  
Mammalian Kidney ◽  
Tubule Cells ◽  
Exchange Activity

Serum and glucocorticoid-regulated kinase 2 (sgk2) is 80% identical to the kinase domain of sgk1, an important mediator of mineralocorticoid-regulated sodium (Na+) transport in the distal nephron of the kidney. The expression pattern and role in renal function of sgk2 are virtually uncharacterized. In situ hybridization and immunohistochemistry of rodent kidney coupled with real-time RT-PCR of microdissected rat kidney tubules showed robust sgk2 expression in the proximal straight tubule and thick ascending limb of the loop of Henle. Sgk2 expression was minimal in distal tubule cells with aquaporin-2 immunostaining but significant in proximal tubule cells with Na+/H+ exchanger 3 (NHE3) immunostaining. To ascertain whether mineralocorticoids regulate expression of sgk2 in a manner similar to sgk1, we examined sgk2 mRNA expression in the kidneys of adrenalectomized rats treated with physiological doses of aldosterone together with the glucocorticoid receptor antagonist RU486. Northern blot analysis and in situ hybridization showed that, unlike sgk1, sgk2 expression in the kidney was not altered by aldosterone treatment. Based on the observation that sgk2 is expressed in proximal tubule cells that also express NHE3, we asked whether sgk2 regulates NHE3 activity. We heterologously expressed sgk2 in opossum kidney (OKP) cells and measured Na+/H+ exchange activity by Na+-dependent cell pH recovery. Constitutively active sgk2, but not sgk1, stimulated Na+/H+ exchange activity by >30%. Moreover, the sgk2-mediated increase in Na+/H+ exchange activity correlated with an increase in cell surface expression of NHE3. Together, these results suggest that the pattern of expression, regulation, and role of sgk2 within the mammalian kidney are distinct from sgk1 and that sgk2 may play a previously unrecognized role in the control of transtubular Na+ transport through NHE3 in the proximal tubule.

Redistribution of microvilli and membrane enzymes in isolated rat proximal tubule cells

1992 ◽  
Vol 74 (2) ◽  
pp. 203-209 ◽  
Author(s):  
Luisa Rebelo ◽  
Maria Carmo-Fonseca ◽  
Teresa Fonseca Moura
Keyword(s):  
Proximal Tubule ◽  
Proximal Tubule Cells ◽  
Membrane Enzymes ◽  
Tubule Cells ◽  
Rat Proximal Tubule ◽  
Isolated Rat

Signaling pathways involved in the rapid biphasic effect of aldosterone on Na + /H + exchanger in rat proximal tubule cells

2018 ◽  
Vol 182 ◽  
pp. 87-94 ◽  
Author(s):  
Deise C.A. Leite-Dellova ◽  
Shirley J. Szriber ◽  
Giovana K.F. Merighe ◽  
Juliano Z. Polidoro ◽  
Nancy A. Rebouças ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Signaling Pathways ◽  
Proximal Tubule Cells ◽  
Biphasic Effect ◽  
Tubule Cells ◽  
Rat Proximal Tubule

Characterization of the beta 2-microglobulin endocytic pathway in rat proximal tubule cells

1994 ◽  
Vol 267 (3) ◽  
pp. F380-F389 ◽  
Author(s):  
D. P. Sundin ◽  
M. Cohen ◽  
R. Dahl ◽  
S. Falk ◽  
B. A. Molitoris
Keyword(s):  
Proximal Tubule ◽  
Endocytic Pathway ◽  
Apical Surface ◽  
Uptake Mechanism ◽  
Proximal Tubule Cells ◽  
Tubule Cells ◽  
Beta 2 ◽  
Beta 2 Microglobulin ◽  
Rat Proximal Tubule

The uptake mechanism(s) of low-molecular-weight proteins by proximal tubule cells remains incompletely characterized. We utilized a biochemical and semiquantitative morphological approach to better characterize the endocytic pathway of an anionic protein, beta 2-microglobulin (beta 2M), in the rat proximal tubule. Indirect immunogold techniques revealed beta 2M was taken up via a classic receptor-mediated endocytic pathway. In vitro biochemical and morphological characterization of iodinated beta 2M and gold-conjugated beta 2M (gold-beta 2M) binding to isolated brush-border membrane vesicles (BBMV) documented specific and quantitatively similar binding interactions of the modified beta 2M with BBMV. Kinetic characterization of the in vivo endocytic pathway of gold-beta 2M was undertaken using microinfusion of individual tubules. beta 2M initially bound at the apical surface, was internalized into subapical coated vesicles and delivered to endosomal-like structures within 5 min, and, finally, was concentrated in lysosomal-like structures within 15 min. This uptake was inhibited by excess unconjugated beta 2M. In addition, we directly showed that uptake did not occur across the basolateral surface. Finally, by passing solubilized BBMV over beta 2M affinity columns we were able to isolate binding activity.

scholarly journals Promoter Analysis of RAT AT2 Receptor Gene in Immortalized Rat Proximal Tubule Cells (IRPTC)

1999 ◽  
Vol 45 (4, Part 2 of 2) ◽  
pp. 337A-337A
Author(s):  
Shiow-Shih Tang ◽  
Daniel E Diamant ◽  
Tim Min ◽  
Julie R Ingelfinger
Keyword(s):  
Proximal Tubule ◽  
Promoter Analysis ◽  
Receptor Gene ◽  
At2 Receptor ◽  
Proximal Tubule Cells ◽  
Tubule Cells ◽  
Rat Proximal Tubule

scholarly journals Toxicity of holotransferrin but not albumin in proximal tubule cells in primary culture.

1998 ◽  
Vol 9 (1) ◽  
pp. 77-84 ◽  
Author(s):  
L Chen ◽  
R A Boadle ◽  
D C Harris
Keyword(s):  
Lipid Peroxidation ◽  
Lactate Dehydrogenase ◽  
Proximal Tubule ◽  
Iron Concentration ◽  
Intracellular Iron ◽  
Proximal Tubule Cells ◽  
Fe Uptake ◽  
Tubule Cells ◽  
Rat Proximal Tubule ◽  
Intracellular Iron Concentration

Proteinuria has been invoked as a cause of tubulointerstitial injury in chronic renal disease, and in vivo studies have suggested indirectly the particular nephrotoxicity of one urinary protein holotransferrin (Tf-Fe). However, to date there has been no direct evidence for the nephrotoxicity of Tf-Fe. To examine the potential cytotoxicity of Tf-Fe and the mechanism involved, and to compare this to another urinary protein albumin, rat proximal tubule cells were studied in primary culture. Tf-Fe at pH 6.0 caused functional and ultrastructural injury, but no cytotoxicity was seen with cells exposed to albumin, apotransferrin (transferrin), or Tf-Fe at pH 7.4. The influence of pH on Tf-Fe-induced cytotoxicity was not due to pH per se, but could be explained by an effect on Tf-Fe uptake. At pH 6.0, uptake of 125I-Tf-Fe (3.55 +/- 0.05 versus 1.25 +/- 0.10 fmol/dish, P < 0.01) and intracellular iron concentration (1.14 +/- 0.25 versus 0.46 +/- 0.23 nmol/dish, P < 0.01) were increased compared with values at pH 7.4. In contrast, pH 6.0 did not increase iron uptake from FeCl3. Lysine (100 mM) inhibited Tf-Fe uptake, decreased intracellular iron concentration, and attenuated Tf-Fe-induced cytotoxicity. The iron chelator des-ferrioxamine (200 microM) and hydroxyl radical scavenger dimethylpyrroline N-oxide (32 mM) abolished lactate dehydrogenase leakage induced by Tf-Fe at pH 6.0. Lipid peroxidation, as assessed by production of malondialdehyde, preceded lactate dehydrogenase leakage. In summary, holotransferrin, but not albumin, is toxic to rat proximal tubule cells, a pH-dependent effect involving its uptake into tubule cells, its iron moiety, and its lipid peroxidation.

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