Effects on Rat Kidney Slice Function In Vitro of Proteins from the Urines of Patients with Myelomatosis and Nephrosis

1974 ◽  
Vol 46 (3) ◽  
pp. 283-294 ◽  
Author(s):  
H. G. Preuss ◽  
F. R. Weiss ◽  
R. M. Iammarino ◽  
W. J. Hammack ◽  
H. V. Murdaugh
Keyword(s):  
Deleterious Effect ◽  
Protein Concentration ◽  
Inverse Relationship ◽  
Rat Kidney ◽  
Light Chains ◽  
Urinary Proteins ◽  
Proximal Tubular ◽  
Proximal Tubular Function ◽  
Urine Proteins

1. The effects were investigated of non-dialysable substances obtained from urines of patients with nephrotic syndrome and those with myelomatosis (heavily laden with light chains) on renal function in a system in vitro. 2. The ability of the rat kidney slice to accumulate hippurate and tetraethylammonium (TEA), and to produce ammonia and glucose, was measured after incubation in urine proteins from ten patients with myelomatosis. All slice functions measured at protein concentrations of 10 mg/ml decreased significantly compared with control. Hippurate accumulation averaged 58%, TEA accumulation, 53%, ammoniagenesis, 59%, and gluconeogenesis, 57% of control. An inverse relationship between protein concentration and hippurate accumulation was noted. 3. Slices incubated in proteins from eight nephrotic patients showed no consistent decrease from control in hippurate accumulation (95%), TEA accumulation (103%), ammoniagenesis (91%) or gluconeogenesis (92%). 4. Since urinary proteins from patients with myelomatosis, unlike urinary proteins from the nephrotic patients, had a consistently deleterious effect on the function of renal slices, this suggests that proteins found in urines from myelomatous patients may play a role in the disturbance of proximal tubular function sometimes seen in this disorder.

In vitro Phosphorylation of Rat Kidney Proximal Tubular Brush Border Membranes

1985 ◽  
Vol 8 (1) ◽  
pp. 19-29
Author(s):  
Jürg Biber ◽  
Vito Sealera ◽  
Heini Murer
Keyword(s):  
Brush Border ◽  
Rat Kidney ◽  
Brush Border Membranes ◽  
Proximal Tubular

scholarly journals Overexpression of MnSOD Protects against Cold Storage-Induced Mitochondrial Injury but Not against OMA1-Dependent OPA1 Proteolytic Processing in Rat Renal Proximal Tubular Cells

Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1272
Author(s):  
Julia Tobacyk ◽  
Grishma KC ◽  
Lee Ann MacMillan-Crow
Keyword(s):  
Cell Viability ◽  
Cold Storage ◽  
Renal Injury ◽  
Rat Kidney ◽  
Proteolytic Processing ◽  
Independent Manner ◽  
Western Blots ◽  
Proximal Tubular ◽  
Dependent Cell

Kidneys from deceased donors undergo cold storage (CS) preservation before transplantation. Although CS is a clinical necessity for extending organ quality preservation, CS causes mitochondrial and renal injury. Specifically, many studies, including our own, have shown that the triggering event of CS-induced renal injury is mitochondrial reactive oxygen species (mROS). Here, we explored the role of OMA1-depedent OPA1 proteolytic processing in rat kidney proximal tubular epithelial (NRK) cells in an in vitro model of renal CS (18 h), followed by rewarming (6 h) (CS + RW). The involvement of mROS was evaluated by stably overexpressing manganese superoxide dismutase (MnSOD), an essential mitochondrial antioxidant enzyme, in NRK cells. Western blots detected rapid OPA1 proteolytic processing and a decrease in ATP-dependent cell viability in NRK cells subjected to CS + RW compared to control cells. Small interfering RNA (siRNA) knockdown of OMA1 reduced proteolytic processing of OPA1, suggesting that OMA1 is responsible for OPA1 proteolytic processing during CS + RW-induced renal injury. Overexpression of MnSOD during CS + RW reduced cell death, mitochondrial respiratory dysfunction, and ATP-dependent cell viability, but it did not prevent OMA1-dependent OPA1 processing. These data show for the first time that OMA1 is responsible for proteolytically cleaving OPA1 in a redox-independent manner during renal cell CS.

Effect of potassium on proximal tubular function

1978 ◽  
Vol 234 (5) ◽  
pp. F381-F385 ◽  
Author(s):  
J. Cardinal ◽  
D. Duchesneau
Keyword(s):  
Renal Tubule ◽  
Potential Difference ◽  
Tubular Function ◽  
Fluid Absorption ◽  
Bathing Medium ◽  
Sodium Potassium ◽  
Proximal Tubular ◽  
Proximal Tubular Function ◽  
Convoluted Tubules

In order to study the effect of potassium on the renal tubule, proximal convoluted tubules were dissected from rabbit kidneys and perfused in vitro. Omitting potassium from both the perfusate and bath caused the rate of fluid absorption and the transtubular potential difference to fall to zero. This effect was due to the absence of potassium in the bathing medium since no change was observed when potassium was omitted from the perfusate only. With 0.5 and 1.0 meq/liter of potassium in the bath, there was still a significant decrease from control in both the potential difference and the rate of fluid absorption. With 2.5 meq/liter of potassium in the bath, the results did not differ from control. In further studies, tubules were perfused with 10 meq/liter of potassium in both perfusate and bath. There was no change in the potential difference of fluid absorption. These results are consistent with the view that active transtubular transport of sodium is linked to the influx of potassium into the cell at the peritubular membrane and that this is probably mediated by sodium-potassium-ATPase. Our results also suggest that the variations of potassium concentration in the physiological range do not affect proximal tubular function.

Different effects of arsenate and phosphonoformate on Pi transport adaptation in opossum kidney cells

2009 ◽  
Vol 297 (3) ◽  
pp. C516-C525 ◽  
Author(s):  
Ricardo Villa-Bellosta ◽  
Víctor Sorribas
Keyword(s):  
Rat Kidney ◽  
Opossum Kidney ◽  
Ok Cells ◽  
Opossum Kidney Cells ◽  
Competitive Inhibitors ◽  
Renal Adaptation ◽  
Proximal Tubular ◽  
Dietary Phosphate ◽  
Definition Of

The main nonhormonal mechanism for controlling inorganic phosphate (Pi) homeostasis is renal adaptation of the proximal tubular Pi transport rate to changes in dietary phosphate content. Opossum kidney (OK) cell line is an in vitro renal model that maintains the ability of renal adaptation to the extracellular Pi concentration. We have studied how two competitive inhibitors of Pi transport, arsenate [As(V)] and phosphonoformate (PFA), affect adaptation to low and high Pi concentrations. OK cells show very high affinity for As(V) (inhibitory constant, Ki 0.12 mM) when compared with the rat kidney. As(V) very efficiently reversed the adaptation of OK cells to low Pi (0.1 mM), whereas PFA induced adaptation similar to 0.1 mM Pi. Adaptation with 2 mM Pi or As(V) was characterized by decreases in the maximal velociy ( Vmax) of Pi transport and an abundance of the NaPi-IIa Pi transporter in the plasma membrane, shown by the protein biotinylation. Conversely, PFA and 0.1 mM Pi increased the Vmax and transporter abundance. Changes in the Vmax were limited to a 50% variation, which was not paralleled by changes in the concentration of Pi or of the inhibitor. OK cells are very sensitive to As(V), but the effects are reversible and noncytotoxic. These effects can be interpreted as As(V) being transported into the cell, thereby mimicking a high Pi concentration. PFA blocks the uptake of Pi but is not transported, and it therefore simulates a low Pi concentration inside the cell. To conclude, a mathematical definition of the adaptation process is reported, thereby explaining the limited changes in Pi transport Vmax.

Tubular handling of neurotensin in the rat kidney as studied by micropuncture and HPLC

1989 ◽  
Vol 256 (1) ◽  
pp. F100-F106
Author(s):  
T. Bjerke ◽  
E. I. Christensen ◽  
N. Boye
Keyword(s):  
High Performance ◽  
Rat Kidney ◽  
Proximal Tubules ◽  
Urinary Recovery ◽  
Rat Serum ◽  
Proximal Tubular ◽  
Distal Tubules ◽  
Extensive Degradation ◽  
Convoluted Tubules

Micropuncture studies were performed to assess the reabsorption and metabolism of the vasoactive peptide neurotensin (NT) in individual nephron segments and compare it to the handling of the closely related peptide bradykinin (BK). Rat proximal and distal convoluted tubules were microinfused with [3H]NT or [3H]BK. In a second set of experiments, [3H]NT and its metabolites in the ureteral urine were separated and characterized using high-performance liquid chromatography (HPLC) technique. The urinary recovery of 3H-labeled material was 31% when proximal tubules were microinfused with [3H]NT and 94% when distal tubules were infused. For proximal tubules the label recovered in the ureteral urine consisted exclusively of metabolites of NT and appeared as tyrosine, NT1-11, probably NT9-13, and two uncharacterized products. For distal tubules, 9% chromatographed as intact NT in the urine and except for the proportion the metabolites were almost identical to those found when proximal tubules were microinfused. Following microinfusion of [3H]BK into proximal tubules, the urinary recovery of 3H-labeled material was 19%. There was no correlation between fractional reabsorption of 3H-labeled material and proximal tubular length when [3H]NT or [3H]BK was microinfused. In vitro incubation studies with rat ureteral urine showed extensive degradation of NT yielding tyrosine, NT1-6, probably NT9-13, NT, and two uncharacterized products. In contrast, there was no detectable breakdown of BK over a 32-min period. Finally, [3H]NT was incubated in rat serum, and these experiments also showed degradation of the peptide but not to the extent as when incubated in ureteral urine.(ABSTRACT TRUNCATED AT 250 WORDS)

Erythrocytes alter the pattern of renal hypoxic injury: predominance of proximal tubular injury with moderate hypoxia

1989 ◽  
Vol 76 (1) ◽  
pp. 19-29 ◽  
Author(s):  
Zoltan H. Endre ◽  
Peter J. Ratcliffe ◽  
John D. Tange ◽  
David J. P. Ferguson ◽  
George K. Radda ◽  
...  
Keyword(s):  
Oxygen Delivery ◽  
Rat Kidney ◽  
Proximal Tubules ◽  
Thick Ascending Limb ◽  
Tubular Injury ◽  
Total Oxygen ◽  
Hypoxic Injury ◽  
Nephron Segment ◽  
Proximal Tubular

1. The distribution of morphological injury was assessed qualitatively and quantitatively in the perfused rat kidney in vitro at controlled rates of oxygen delivery in the presence of low concentrations of erythrocytes. 2. In control kidneys (total oxygen delivery approximately 32 μmol/min per kidney) no injury was seen in the medullary thick ascending limb of Henle's loop (MTAL) whilst 11 ± 5 (sd)% of proximal tubules sustained damage. 3. Mild hypoxia (total oxygen delivery approximately 28 μmol/min per kidney) produced little or no injury to MTAL, namely 6 ± 4(sd)% and 3 ± 3% of tubules damaged, respectively. In contrast, both groups sustained extensive damage to proximal tubules, averaging 46 ± 13% (P < 0.01 vs control) and 84 ± 14% (P < 0.001 vs control), respectively. This damage was equally distributed between the superficial and deep cortex. 4. Comparison with morphometric data obtained previously from cell-free-perfused rat kidneys [P. J. Ratcliffe, Z. H. Endre, S. J. Scheinman, J. D. Tange, J. G. G. Ledingham & G. K. Radda (1988) Clinical Science74, 437–448] showed that (a) erythrocytes prevent hypoxic damage to the MTAL at mild and moderate levels of hypoxia; (b) when oxygen delivery rates are matched between cell-free- and erythrocyte-perfused kidneys, proximal tubular injury is greater in the presence of erythrocytes; (c) when arterial partial pressure of oxygen is matched between cell-free- and erythrocyte-perfused kidneys, the degree of proximal tubular injury is similar. 5. The data suggest that the proximal tubule and not the MTAL is the nephron segment most at risk of hypoxic injury in vitro.

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