Renal hydrolysis of absorbed protein: influence of load and lysosomal pH

1984 ◽  
Vol 247 (4) ◽  
pp. F656-F664 ◽  
Author(s):  
M. J. Camargo ◽  
B. E. Sumpio ◽  
T. Maack
Keyword(s):  
Rat Kidney ◽  
High Capacity ◽  
Lysosomal Ph ◽  
Renal Tubular Cells ◽  
Weak Bases ◽  
Uptake Rates ◽  
Cyt C ◽  
Renal Tubular ◽  
Hydrolysis Of

The kinetics of intracellular hydrolysis of administered protein and the effect of alkalinization of lysosomal pH on this process were studied in the isolated perfused rat kidney (IPK). Cytochrome c (CYT c) was used as a probe protein, and its hydrolysis was determined by measuring the efflux of radioactivity from IPK preloaded in vivo with [14CH3]CYT c and various doses of unlabeled CYT c. The nature of radioactivity absorbed by the kidney and released to the perfusate was analyzed by Sephadex chromatography. Administered CYT c is absorbed and hydrolyzed by the kidney, and the resulting amino acids are returned to the perfusate. At low uptake rates, the half time of hydrolysis of absorbed CYT c is about 20 min. The disposal of absorbed CYT c is a saturable function of its concentration in kidney with a Vmax = 0.60 mg CYT c X h-1 X g kidney-1 and an apparent Km = 0.55 mg CYT c/g kidney. To alkalinize the lysosomal pH, IPK were perfused in the presence of NH4Cl (10 mM) or chloroquine (0.1 mM). These lysosomotropic weak bases almost completely inhibit in a reversible manner the hydrolysis of absorbed CYT c. The results demonstrate that renal catabolism of absorbed protein is a saturable process of high capacity compared with the normal filtered loads of protein. The data are consistent with the view that normal lysosomal function is required for an adequate disposal of absorbed proteins in the kidney. It is postulated that abnormal deposition of protein absorption droplets within renal tubular cells may result from high absorbed loads and/or a deficient acidification of lysosomes.

scholarly journals Cellular Uptake and Localization of Polymyxins in Renal Tubular Cells Using Rationally Designed Fluorescent Probes

2015 ◽  
Vol 59 (12) ◽  
pp. 7489-7496 ◽  
Author(s):  
Bo Yun ◽  
Mohammad A. K. Azad ◽  
Cameron J. Nowell ◽  
Roger L. Nation ◽  
Philip E. Thompson ◽  
...  
Keyword(s):  
Cellular Uptake ◽  
Rat Kidney ◽  
Antimicrobial Activities ◽  
Core Structure ◽  
Confocal Imaging ◽  
Limiting Factor ◽  
Tubular Cells ◽  
Renal Tubular Cells ◽  
Renal Tubular ◽  
Apoptotic Effects

ABSTRACTPolymyxins are cyclic lipopeptide antibiotics that serve as a last line of defense against Gram-negative bacterial superbugs. However, the extensive accumulation of polymyxins in renal tubular cells can lead to nephrotoxicity, which is the major dose-limiting factor in clinical use. In order to gain further insights into the mechanism of polymyxin-induced nephrotoxicity, we have rationally designed novel fluorescent polymyxin probes to examine the localization of polymyxins in rat renal tubular (NRK-52E) cells. Our design strategy focused on incorporating a dansyl fluorophore at the hydrophobic centers of the polymyxin core structure. To this end, four novel regioselectively labeled monodansylated polymyxin B probes (MIPS-9541, MIPS-9542, MIPS-9543, and MIPS-9544) were designed, synthesized, and screened for their antimicrobial activities and apoptotic effects against rat kidney proximal tubular cells. On the basis of the assessment of antimicrobial activities, cellular uptake, and apoptotic effects on renal tubular cells, incorporation of a dansyl fluorophore at either position 6 or 7 (MIPS-9543 and MIPS-9544, respectively) of the polymyxin core structure appears to be an appropriate strategy for generating representative fluorescent polymyxin probes to be utilized in intracellular imaging and mechanistic studies. Furthermore, confocal imaging experiments utilizing these probes showed evidence of partial colocalization of the polymyxins with both the endoplasmic reticulum and mitochondria in rat renal tubular cells. Our results highlight the value of these new fluorescent polymyxin probes and provide further insights into the mechanism of polymyxin-induced nephrotoxicity.

Localization of heparin and low-molecular-weight heparin in the rat kidney

2004 ◽  
Vol 91 (05) ◽  
pp. 927-934 ◽  
Author(s):  
Vivian Douros ◽  
Thomas Podor ◽  
Stephen Shaughnessy ◽  
Jeffrey Weitz ◽  
Edward Young
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Rat Kidney ◽  
Organic Anion ◽  
Molecular Size ◽  
Immunohistochemical Analysis ◽  
Immunoperoxidase Staining ◽  
Low Molecular Weight ◽  
Renal Tubular Cells ◽  
Renal Tubular

SummaryUnfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) are cleared, at least in part, by the kidneys through a poorly understood process. This study was undertaken to explore the mechanism of renal clearance of these drugs. Rats were given fluorescein-5-isothiocyanate (FITC)-labeled UFH or LMWH intravenously. At intervals after injection, rats were euthanized and the kidneys were harvested and subjected to immunohistochemical analysis and fluorescence microscopy. Both UFH and LMWH were localized to renal tubular cells and no immunoperoxidase staining or fluorescence was detected in glomeruli. Autoradiography demonstrated similar intracellular distribution of radio-labeled UFH suggesting that this phenomenon is independent of the method used to label heparin. Fluoresence in the tubules increased as a function of time after UFH injection, but reached a plateau after LMWH injection suggesting that the rate of renal tubular uptake depends on the molecular size of the heparin. When administered prior to FITC-labeled UFH or LMWH, probenecid, a renal organic anion inhibitor, decreased the renal tubular uptake of the heparins, whereas cimetidine, a renal organic cation inhibitor, had no effect. These findings suggest that renal excretion of UFH and LMWH primarily reflects tubular uptake via an organic anion transport mechanism.

Time course and vectorial nature of albumin metabolism in isolated perfused rabbit PCT

1988 ◽  
Vol 255 (3) ◽  
pp. F520-F528 ◽  
Author(s):  
C. H. Park
Keyword(s):  
Time Course ◽  
Hydrolysis Product ◽  
High Capacity ◽  
Intact Protein ◽  
Renal Metabolism ◽  
First Order ◽  
First Order Kinetics ◽  
Hydrolysis Products ◽  
Renal Tubular ◽  
Hydrolysis Of

The time course and vectorial nature of renal metabolism of albumin (Alb) were studied. The tubular absorption, accumulation, and hydrolysis of Alb and the release of the hydrolysis products were determined in the isolated rabbit proximal convoluted tubule (PCT) perfused with tritiated Alb ([3H3C]Alb) at 36.4 micrograms/ml. The Alb absorption across the apical membrane was constant (99.9 +/- 4.9 x 10(-3) ng.min-1.mm-1). In contrast, the accumulation and hydrolysis of Alb in the cells increased nonlinearly with time. The bulk of the tritium that accumulated in the cells was associated with intact [3H3C]Alb. Only the final hydrolysis products were released from the cells and these first appeared in the peritubular bath 6–7 min after the start of perfusion of the tubule with [3H3C]Alb. The hydrolysis product was not detectable in the tubule lumen. The proteolytic activity correlated linearly with the protein load to the cells, characteristic of first-order kinetics and a high-capacity system. The results suggest that the renal tubular handling of proteins proceeds from the apical to the basolateral aspect of the cell. The transcellular processing of Alb is rapid and can occur in 6–7 min. The accumulation of intact protein in the cell and the first-order kinetics of hydrolysis of the absorbed protein suggest that the rate-limiting step in proximal tubular handling of proteins may include the initial hydrolysis of protein or reside in steps that precede the hydrolysis.

Uptake of Pi in brush border vesicles after release of unilateral ureteral obstruction

1982 ◽  
Vol 243 (1) ◽  
pp. F29-F35
Author(s):  
S. Weinreb ◽  
K. A. Hruska ◽  
S. Klahr ◽  
M. R. Hammerman
Keyword(s):  
Brush Border ◽  
Ureteral Obstruction ◽  
Membrane Vesicles ◽  
Fractional Excretion ◽  
Unilateral Ureteral Obstruction ◽  
Renal Tubular Cells ◽  
Pi Transport ◽  
Renal Tubular ◽  
And Control

After release of complete unilateral ureteral obstruction, a decreased fractional excretion of phosphate (Pi) is observed in the postobstructed kidney compared with the nonobstructed (control) kidney. To determine whether this decrease in the urinary excretion of Pi is due to changes in Na+-dependent Pi transport across the renal brush border membranes of postobstructed and control kidneys, membrane vesicles were prepared from the brush borders of kidneys from dogs that had undergone complete unilateral ureteral obstruction. Alkaline phosphatase activity was decreased in membrane vesicles isolated from postobstructed kidneys. No differences were observed in Na+-dependent Pi transport or in Na+ uptake in membrane vesicles isolated from postobstructed as compared with control kidneys. The in vivo administration of parathyroid hormone decreased Na+-dependent Pi transport in membrane vesicles isolated from postobstructed and control kidneys despite the absence of a phosphaturic response. Our findings suggest that no intrinsic change in the transport characteristics of Pi across the luminal membrane of renal tubular cells occurs with unilateral ureteral obstruction. The findings are consistent with the suggestion that the low fractional excretion of Pi in the postobstructed kidney results from very low filtered loads of Pi on the postobstructed side.

Cystine and lysine reabsorption in the isolated perfused rat kidney

1989 ◽  
Vol 256 (5) ◽  
pp. F901-F908
Author(s):  
K. A. Roby ◽  
S. Segal
Keyword(s):  
Transport System ◽  
Brush Border ◽  
Rat Kidney ◽  
Isolated Perfused Rat Kidney ◽  
Transport Studies ◽  
Perfused Rat Kidney ◽  
Renal Tubular Reabsorption ◽  
Renal Tubular

Renal tubular reabsorption of cystine and lysine were studied in the isolated perfused rat kidney to bridge the gap between in vivo clearance studies, and in vitro transport studies of tubule fragments, cells, and brush-border membranes. Lysine was reabsorped by a saturable transport system shared by the dibasics. Cystine was also reabsorbed by a saturable transport system, which was shared in part by the dibasics (maximum inhibition 30%). The lysine threshold (Fmin) was 0.9 mumol.min-1.g-1, with a tubular maximum (TM) of 2.4 mumol.min-1.g-1. The cystine Fmin was 0.06 mumol.min-1.g-1; the TM could not be estimated because it was above the limit of cystine solubility. There was no evidence of cystine ,secretion.- The gamma-glutamyltransferase inhibitor, AT-125, decreased cystine excretion, but only in the presence of glutathione, glycine, glutamate, and the diabasic amino acids. This suggests that cystine from glutathione degradation at the brush border may contribute to urinary cystine (an explanation of the phenomenon of cystine secretion), but only under certain conditions.

scholarly journals Isolation, partial characterization, and localization of a rat renal tubular glycoprotein antigen. Antibody-induced birth defects.

1982 ◽  
Vol 156 (2) ◽  
pp. 372-384 ◽  
Author(s):  
C C Leung
Keyword(s):  
Birth Defects ◽  
Rat Kidney ◽  
Polyacrylamide Gel Electrophoresis ◽  
Yolk Sac ◽  
Affinity Column ◽  
Immunofluorescent Localization ◽  
Renal Tubular Cells ◽  
Visceral Yolk Sac ◽  
Renal Tubular ◽  
Endodermal Cells

A glycoprotein with an apparent 340,000 mol wt (gp 340K) was isolated from rat kidney saline-soluble extract by ammonium sulfate precipitation, DE 52 ion-exchange cellulose chromatography, concanavalin A affinity column, Sephacryl S-300 gel filtration, and discontinuous polyacrylamide gel electrophoresis (PAGE). The relative purity of gp 340K was examined by double immunodiffusion analysis, disc PAGE, and immunoelectrophoresis. Injection of rabbit gp 340K antiserum into pregnant rats during the organogenetic period induced abnormal embryonic development, fetal growth retardation, and embryonic death. Antiserum against the immunocomplexes isolated by immobilized protein A also produced the same embryotoxic effects. The biologic effects of the antisera appeared to be dose dependent. Defects such as anophthalmia, hydrocephaly, exencephaly, cleft palate, cleft lip, and some cardiovascular anomalies were observed. The most frequently observed anomaly was anophthalmia. Immunofluorescent localization studies indicated that gp 340K antibodies localized in vivo in the visceral yolk-sac endodermal cells and the embryonic endoderm. In vitro immunofluorescent localization studies revealed that gp 340K was a component of the renal tubular cells that cross-reacted with antigen in the visceral yolk-sac endodermal cells and embryonic endoderm. The underlying mechanism whereby gp 340K antibodies induce birth defects is not known. Three hypotheses were discussed.

Occurrence and pathology of mycotoxins in commercial parrot feeds

2013 ◽  
Vol 6 (4) ◽  
pp. 449-453 ◽  
Author(s):  
S.-J. Li ◽  
E. Njumbe Ediage ◽  
S. De Saeger ◽  
L. Van Waeyenberghe ◽  
A. Garmyn ◽  
...  
Keyword(s):  
Body Weight Gain ◽  
Control Group ◽  
Potential Threat ◽  
Renal Tubular Cells ◽  
Liquid Chromatography Tandem Mass ◽  
Pelleted Feed ◽  
Group 2 ◽  
Renal Tubular ◽  
Aflatoxin B

Mycotoxins are toxic secondary metabolites of fungi. Animal feeds can be easily infected by fungi during production and storage, resulting in mycotoxin contamination. This study was performed to evaluate the possible health risks of mycotoxin-contaminated feed for cockatiels. The occurrence of mycotoxins in commercial parrot feeds (5 seed mixes and 5 pelleted feeds) was investigated by liquid chromatography tandem mass spectrometry. The following 12 mycotoxins were detected: zearalenone, deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, fusarenon X, aflatoxin B1, sterigmatocystin, alternariol, alternariol methylether, fumonisin B1, fumonisin B3, and ochratoxin A. Zearalenone was the most prevalent. Pathological effects after 21 days feeding mycotoxin-contaminated diets were examined in an in vivo trial with 3 groups of 5 cockatiels: group 1 (control) was fed a non-contaminated pelleted feed; group 2 was fed a pelleted feed containing zearalenone, deoxynivalenol, 15-acetyldeoxynivalenol, and fumonisins; and group 3 was fed a pelleted feed containing fumonisins. Average body weight gain and relative organ weight were not significantly different between the treatment groups and the control group. Apoptosis of renal tubular cells, diarrhoea, reduced appetite, enlargement of liver, kidney and proventriculus were occasionally observed in the birds from groups 2 and 3. In summary, contamination with mycotoxins is common in parrot feeds. The mycotoxin levels did not reach toxic levels, but might pose a potential threat to some sensitive cockatiels.

scholarly journals Increasing cGMP-dependent protein kinase I activity attenuates cisplatin-induced kidney injury through protection of mitochondria function

2013 ◽  
Vol 305 (6) ◽  
pp. F881-F890 ◽  
Author(s):  
Hasiyeti Maimaitiyiming ◽  
Yanzhang Li ◽  
Wenpeng Cui ◽  
Xiaopeng Tong ◽  
Heather Norman ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Tubular Damage ◽  
Dependent Protein Kinase ◽  
Tubular Cells ◽  
Renal Tubular Cells ◽  
Cgmp Dependent Protein Kinase ◽  
Dependent Protein ◽  
Renal Tubular

Cisplatin is widely used to treat malignancies. However, its major limitation is the development of dose-dependent nephrotoxicity. The precise mechanisms of cisplatin-induced kidney damage remain unclear, and the renoprotective agents during cisplatin treatment are still lacking. Here, we demonstrated that the expression and activity of cGMP-dependent protein kinase-I (PKG-I) were reduced in cisplatin-treated renal tubular cells in vitro as well as in the kidney tissues from cisplatin-treated mice in vivo. Increasing PKG activity by both pharmacological and genetic approaches attenuated cisplatin-induced kidney cell apoptosis in vitro. This was accompanied by decreased Bax/Bcl2 ratio, caspase 3 activity, and cytochrome c release. Cisplatin-induced mitochondria membrane potential loss in the tubular cells was also prevented by increased PKG activity. All of these data suggest a protective effect of PKG on mitochondria function in renal tubular cells. Importantly, increasing PKG activity pharmacologically or genetically diminished cisplatin-induced tubular damage and preserved renal function during cisplatin treatment in vivo. Mitochondria structural and functional damage in the kidney from cisplatin-treated mice was inhibited by increased PKG activity. In addition, increasing PKG activity enhanced ciaplatin-induced cell death in several cancer cell lines. Taken together, these results suggest that increasing PKG activity may be a novel option for renoprotection during cisplatin-based chemotherapy.

scholarly journals The Predictive Role of the Biomarker Kidney Molecule-1 (KIM-1) in Acute Kidney Injury (AKI) Cisplatin-Induced Nephrotoxicity

2019 ◽  
Vol 20 (20) ◽  
pp. 5238 ◽  
Author(s):  
Daniela Maria Tanase ◽  
Evelina Maria Gosav ◽  
Smaranda Radu ◽  
Claudia Florida Costea ◽  
Manuela Ciocoiu ◽  
...  
Keyword(s):  
Acute Kidney Injury ◽  
Kidney Injury ◽  
In Vivo Studies ◽  
Renal Tubular Cells ◽  
Renal Tubular ◽  
Induced Apoptosis ◽  
Kidney Injury Molecule 1

Acute kidney injury (AKI) following platinum-based chemotherapeutics is a frequently reported serious side-effect. However, there are no approved biomarkers that can properly identify proximal tubular injury while routine assessments such as serum creatinine lack sensitivity. Kidney-injury-molecule 1 (KIM-1) is showing promise in identifying cisplatin-induced renal injury both in vitro and in vivo studies. In this review, we focus on describing the mechanisms of renal tubular cells cisplatin-induced apoptosis, the associated inflammatory response and oxidative stress and the role of KIM-1 as a possible biomarker used to predict cisplatin associated AKI.

11 beta-Hydroxysteroid dehydrogenase mRNA expression in rat kidney

1991 ◽  
Vol 260 (5) ◽  
pp. F764-F767
Author(s):  
J. L. Yau ◽  
A. D. Van Haarst ◽  
M. P. Moisan ◽  
S. Fleming ◽  
C. R. Edwards ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Binding Sites ◽  
Mineralocorticoid Receptor ◽  
Rat Kidney ◽  
Hydroxysteroid Dehydrogenase ◽  
Mineralocorticoid Receptors ◽  
Tubular Cells ◽  
Renal Tubular

11 beta-Hydroxysteroid dehydrogenase (11 beta-OHSD) protects nonspecific renal mineralocorticoid receptors from exposure to circulating glucocorticoid in vivo by catalyzing the conversion of corticosterone to inactive 11-dehydrocorticosterone. Although 11 beta-OHSD bioactivity and aldosterone binding sites are found in distal tubular cells, mineralocorticoid receptor and 11 beta-OHSD immunoreactivities are not colocalized. However, there are several kidney isoforms of 11 beta-OHSD, not all of which may be immunoreactive, whereas only a single mRNA species has been described. Using in situ hybridization we found 11 beta-OHSD mRNA is highly expressed in all renal tubular epithelia in the rat. It is therefore likely that 11 beta-OHSD is colocalized with mineralocorticoid receptors in distal tubular cells.

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