High affinity Ca2+–Mg2+ ATPase in the distal tubule of the mouse kidney

1987 ◽  
Vol 65 (10) ◽  
pp. 2093-2098 ◽  
Author(s):  
Michèle G. Brunette ◽  
Sylvie Blouin ◽  
Meathan Chan
Keyword(s):  
Proximal Tubule ◽  
Kinetic Parameters ◽  
Atp Hydrolysis ◽  
Limit Of Detection ◽  
Distal Tubule ◽  
Mouse Kidney ◽  
Distal Nephron ◽  
Low Concentrations ◽  
Distal Tubules ◽  
Shed Light

The purpose of this study was to investigate whether Ca2+–Mg2+ ATPase in the distal tubule (where calcium transport is active, against a gradient, and hormone dependent) presents some characteristics different from those observed in the proximal tubule, and whether these characteristics are likely to shed light on the respective roles of this enzyme at the two sites of the nephron. The Ca2+- and Mg2+-dependent ATP hydrolysis was measured in microdissected segments of the distal nephron, the kinetic parameters were determined, and the influence of magnesium upon the sensitivity to calcium was examined. Results were compared with those obtained in the proximal tubule, and in purified membranes as reported by others. In the distal tubule, low concentrations of Mg2+ (< 10−7 M) did not influence ATP hydrolysis. At concentrations above 10−7 M, Mg2+ increased ATP hydrolysis according to Michaelis kinetics (apparent Km = 11.3 ± 2.4 μM, Vmax = 219 ± 26 pmol∙mm−1∙20 min−1). The addition of 1 μM Ca2+ decreased the apparent Km for Mg2+ and the Vmax for Mg2+. Similar results were obtained in the proximal tubule. At low Mg2+ concentrations, Ca2+ also stimulated ATP hydrolysis according to Michaelis kinetics with an apparent Km value for Ca2+ of 0.18 ± 0.06 and 0.10 ± 0.03 μM Ca2+ (ns) and a Vmax of 101 ± 12 and 89 ± 9 pmol∙mm−1∙20 min−1 (ns) in the distal and proximal tubules, respectively. In the two segments, the addition of Mg2+ strongly decreased the sensitivity to 1 μM Ca2+ so that at 1 mM Mg2+, the Ca2+-dependent ATPase activity was at the limit of detection. In conclusion, the kinetic parameters of the Ca2+- and Mg2+-dependent ATP hydrolysis were similar at the two sites of the nephron, and were also similar to those reported for the enzyme present in purified basolateral membranes. The nonadditive effect of the two cations Ca2+ and Mg2+ suggests that the two ATPase activities belong to the same enzyme, and this enzyme is the same in the proximal and distal tubules. Differences in Ca2+ transport characteristics should be attributed to factors other than variations in the nature of the Ca2+–Mg2+ ATPase.

scholarly journals Endopeptidases (kininases) are able to hydrolyze kinins in tubular fluid along the rat nephron

1999 ◽  
Vol 277 (1) ◽  
pp. F66-F74 ◽  
Author(s):  
D. E. Casarini ◽  
M. A. Boim ◽  
R. C. R. Stella ◽  
N. Schor
Keyword(s):  
Angiotensin Converting Enzyme ◽  
Proximal Tubule ◽  
Physiological Role ◽  
Distal Tubule ◽  
Neutral Endopeptidase ◽  
Prolyl Endopeptidase ◽  
Proximal Tubules ◽  
Converting Enzyme ◽  
Distal Nephron ◽  
Distal Tubules

The activities of serine endopeptidase, prolyl endopeptidase and neutral endopeptidase were determined in tubular fluid collected from several portions of the rat nephron as well as in urine. The enzyme activities were measured by HPLC using bradykinin (BK) as substrate. Free residual peptides of BK obtained by the action of these enzymes on the locally produced BK were also determined. The endopeptidase activities were found to be present throughout the nephron. Equimolar fragments of BK were detected in the early proximal tubule (Arg1-Pro7, Phe8-Arg9, Arg1-Gly4, Phe5-Arg9, and BK), late proximal tubule (Arg1-Phe5, Arg1-Pro7, Gly4-Pro7, Gly4-Arg9, and BK), late distal tubule (Arg1-Gly4, Phe5-Arg9, Arg1-Phe5, Ser6-Arg9, Gly4-Arg9, BK, and [des-Arg9]BK) and urine (Phe8-Arg9, Phe5-Arg9, Arg1-Phe5, Ser6-Arg9, Arg1-Pro7, Gly4-Pro7, Gly4-Arg9, BK, and [des-Arg9]BK). Our data suggest that the endopeptidases and exopeptidases are secreted by the nephron. Early proximal tubules secrete angiotensin converting enzyme and neutral endopeptidase, differing from late distal tubules that produce prolyl endopeptidase, serine endopeptidase, carboxypeptidase, and also neutral endopeptidase. All enzymes detected along the rat nephron were found in the urine. The existence of endopeptidases and carboxypeptidase in the distal nephron may have a potential physiological role in the inactivation of the kinins formed by kallikrein in the kidney and also in the inactivation of additional peptides other than BK.

scholarly journals Sex differences in proximal and distal nephron function contribute to the mechanism of idiopathic hypercalcuria in calcium stone formers

2015 ◽  
Vol 309 (1) ◽  
pp. R85-R92 ◽  
Author(s):  
Benjamin Ko ◽  
Kristin Bergsland ◽  
Daniel L. Gillen ◽  
Andrew P. Evan ◽  
Daniel L. Clark ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Distal Tubule ◽  
Normal Subjects ◽  
Idiopathic Hypercalciuria ◽  
Distal Nephron ◽  
Stone Formers ◽  
Calcium Reabsorption ◽  
Normal Women ◽  
Normal Males ◽  
Normal Men

Idiopathic hypercalciuria (IH) is a common familial trait among patients with calcium nephrolithiasis. Previously, we have demonstrated that hypercalciuria is primarily due to reduced renal proximal and distal tubule calcium reabsorption. Here, using measurements of the clearances of sodium, calcium, and endogenous lithium taken from the General Clinical Research Center, we test the hypothesis that patterns of segmental nephron tubule calcium reabsorption differ between the sexes in IH and normal subjects. When the sexes are compared, we reconfirm the reduced proximal and distal calcium reabsorption. In IH women, distal nephron calcium reabsorption is decreased compared to normal women. In IH men, proximal tubule calcium reabsorption falls significantly, with a more modest reduction in distal calcium reabsorption compared to normal men. Additionally, we demonstrate that male IH patients have lower systolic blood pressures than normal males. We conclude that women and men differ in the way they produce the hypercalciuria of IH, with females reducing distal reabsorption and males primarily reducing proximal tubule function.

scholarly journals Light and electron microscopic localization of the alpha 1-chain and the E1 and E8 domains of laminin-1 in mouse kidney using monoclonal antibodies to establish the orientation of laminin-1 within basement membranes.

1995 ◽  
Vol 43 (7) ◽  
pp. 675-680 ◽  
Author(s):  
N Miosge ◽  
E Günther ◽  
E Heyder ◽  
B Manshausen ◽  
R Herken
Keyword(s):  
Monoclonal Antibodies ◽  
Proximal Tubule ◽  
Distal Tubule ◽  
Distinct Pattern ◽  
Mouse Kidney ◽  
Basement Membranes ◽  
Mouse Tissue ◽  
Electron Microscopic ◽  
Laminin 1

To localize the different domains of the laminin-1 molecule in tissues and gain insight into their in vivo relevance, we raised rat anti-mouse monoclonal antibodies (MAbs) against the entire molecule. Then we tested eight of the 20 clones producing anti-laminin-1 MAbs to specify their reactivity towards the alpha 1-, beta 1-, and gamma 1-chains and the elastase-cleaved fragments of the laminin-1 molecule. We found three MAbs with high titers in ELISA that showed good reactivity in embedded tissue. One of these reacted specifically against the E1 fragment, one against the E8 fragment, and one MAb detected the alpha 1-chain of laminin-1 but not the beta 1- or gamma 1-chain. All three MAbs are useful for light immunohistochemical investigations on cryosections and on paraffin-embedded material, and for ultrastructural localization of laminin-1 in LR Gold-embedded mouse tissue. Antibody staining of the E1 and E8 domains of laminin-1 revealed distinct localization of the molecule in the proximal tubule basement membranes of mouse kidney. The short arms (E1) of the laminin-1 molecule are predominantly located in the lamina lucida and the long arms (E8) are oriented towards the lamina fibroreticularis. Therefore, both MAbs are useful for studies of the orientation of the laminin-1 molecule in basement membranes. The distal tubule basement membranes did not show any distinct pattern of laminin-1 distribution. In general, the distal tubules showed the strongest reactions over the entire width of the basement membrane for all three MAbs. In contrast, the proximal tubule basement membranes showed somewhat weaker reactivity but a distinct pattern of laminin-1 distribution, with the E1 fragments oriented towards the adjacent epithelial cell surface.

X-ray microanalysis of proximal and distal tubule cells in the mouse kidney, and the influence of cadmium on the concentration of natural intracellular elements

1983 ◽  
Vol 62 (1) ◽  
pp. 319-338
Author(s):  
M.D. Kendall ◽  
A. Warley ◽  
J.K. Nicholson ◽  
T.C. Appleton
Keyword(s):  
Distal Tubule ◽  
Absorption Spectrometry ◽  
Dry Weight ◽  
Mouse Kidney ◽  
Subcutaneous Injections ◽  
X Ray ◽  
Cadmium Treatment ◽  
Mouse Cortex ◽  
Freeze Dried ◽  
Distal Tubules

Quantitative X-ray microanalysis of frozen freeze-dried sections of mouse cortex have been used to determine the concentrations of Na, Mg, P, S, Cl, K, Ca and Cd in normal mice and those subjected t 0.7 mumol of cadmium chloride in two subcutaneous injections. These injections result in tissue levels of approximately 100 mg Cd/kg dry weight (less than 1 mM) in whole kidney when analysed by atomic absorption spectrometry. There were distinct and characteristic differences — ‘fingerprints’ — in the elemental composition of both cytoplasm and mitochondria in proximal and distal tubules of normal mice that were distributed by the cadmium treatment. The most significant effect of the cadmium injections was a highly significant increase in the sulphur content of the cytoplasm and mitochondria of distal tubules and a loss in concentration of Mg, P, Cl, K, and particularly Na, from the mitochondria. These results are discussed in the light of current concepts of metallothionein induction (metallothionein is a sulphur-rich protein that acts to bind, amongst other metals, cadmium) and the lack of damage observed in the distal tubules.

Relation of distal tubular delivery and reabsorptive rate to nephron filtration

1977 ◽  
Vol 233 (4) ◽  
pp. F315-F324 ◽  
Author(s):  
R. C. Blantz ◽  
K. S. Konnen
Keyword(s):  
Proximal Tubule ◽  
Filtration Rate ◽  
Distal Tubule ◽  
Tubuloglomerular Feedback ◽  
Perfusion Rate ◽  
Group Iii ◽  
Group I ◽  
Proximal Tubular ◽  
Distal Tubules ◽  
Group Ii

The tubuloglomerular feedback hypothesis states that filtration rate in a single nephron unit (SNGFR) is controlled or modified through variations in the rate of either distal delivery or tubular reabsorption in that same nephron. We have reexamined this hypothesis by varying the perfusion rate of the late proximal tubule from normal (10 nl/min) to supranormal values (30 nl/min) in a reversible fashion and measured the resultant nephron filtration rate. Three perfusion fluid were utilized: group I, a solution simulating late proximal tubular fluid (11 mM HCO3); group II, a solution with a higher HCO3 concentration (30 mM HCO3); and group III, a solution simulating early proximal tubular fluid. In group I SNGFR was 27.2 nl/min during perfusion from the late proximal tubule at 10 nl/min and fell to 19.8 nl/min during the 30 nl/min perfusion rate. Group II SNGFR was 27.7 nl/min at the 10 nl/min rate and 19.0 nl/min during the 30 nl/min perfusion. Groups I and II then demonstrated a completely reversible tubuloglomerular feedback response. In group III, the SNGFR at 10 nl/min was 26.2 nl/min and 23.4 nl/min at the 30 nl/min perfusion rate and were significantly different. Evaluation of collections of distal tubule fluid in perfused nephrons revealed that increased absolute reabsorption of water and chloride between late proximal and distal tubules was associated with the reductions in SNGFR in the same nephron. A strong candidate for the afferent limb of this system is the change in absolute chloride reabsorption between late proximal and distal tubules.

Depressed distal tubule acidification corrects chloride-deplete alkalosis in rats

1990 ◽  
Vol 259 (4) ◽  
pp. F636-F644 ◽  
Author(s):  
D. E. Wesson
Keyword(s):  
Linear Regression ◽  
Proximal Tubule ◽  
Metabolic Alkalosis ◽  
Wistar Rats ◽  
Distal Tubule ◽  
Bicarbonate Reabsorption ◽  
Dependent Relationship ◽  
Distal Tubules ◽  
Lower Slope ◽  
Filtered Load

We investigated the relative contributions made by the proximal and distal tubule to the correction of Cl-deplete metabolic alkalosis induced by systemic administration of NaCl. Free-flow micropuncture was used to examine net bicarbonate reabsorption in superficial proximal and distal tubules of anesthetized Munich-Wistar rats during maintenance and correction of chronic furosemide-induced Cl-deplete metabolic alkalosis. The distal tubule of animals with correcting vs. maintained alkalosis had a lower fractional reabsorption of bicarbonate (38 vs. 75%, P less than 0.001) and a lower slope of the linear regression comparing absorption to delivered load (0.48 vs. 0.99, P less than 0.02). By contrast, proximal tubule of animals with correcting vs. maintained alkalosis had fractional reabsorption (85 vs. 90%, P = 0.07) and slopes of the regression comparing reabsorption to filtered load (1.09 vs. 0.98, P = 0.48) that were not different. The data indicate that correction of Cl-deplete metabolic alkalosis induced by NaCl administration involves a qualitative decreased in bicarbonate reabsorption in distal tubule with maintenance of the same load-dependent relationship for bicarbonate reabsorption in proximal tubule.

Distal perfusion studies: transport stimulation by native tubule fluid

1990 ◽  
Vol 258 (6) ◽  
pp. F1523-F1527 ◽  
Author(s):  
G. Malnic ◽  
R. W. Berliner ◽  
G. Giebisch
Keyword(s):  
Proximal Tubule ◽  
Distal Tubule ◽  
Free Flow ◽  
Flow Conditions ◽  
Perfusion Studies ◽  
Potassium Secretion ◽  
Series Of Experiments ◽  
Distal Tubules ◽  
Distal Perfusion ◽  
Tubule Fluid

It is well established that potassium secretion into the distal tubule increases with the rate of flow. In a previous study [G. Malnic, R. W. Berliner, and G. Giebisch. Am. J. Physiol. 256 (Renal Fluid Electrolyte Physiol. 25): F932-F1271, 1989] we found that the increase with the rate of perfusion with a fluid made up to resemble that normally found in the early distal tubule was substantially less than the increase in free-flow conditions [R. N. Khuri, M. Wiederholt, N. Strieder, and G. Giebisch. Am. J. Physiol. 228: 1249–1261, 1975]. Because of the possibility that some important component was missing from the artificial fluid, we have carried out another series of experiments in which distal tubules were perfused with fluid collected from late proximal tubules and compared the results with those obtained when tubules were perfused with an artificial fluid with an electrolyte composition similar to that of late proximal fluid. When proximal tubule fluid was used, the potassium concentrations in the collected distal fluid were higher and better maintained with increasing flow than when the artificial fluid was used, and consequently the rate of potassium secretion was substantially greater with the proximal tubule fluid, approaching the results of previous studies in free flow. The nature of the component missing from the artificial solution is not known.

scholarly journals The mechanism of bicarbonate reabsorption in the proximal and distal tubules of the kidney. 1965.

1998 ◽  
Vol 9 (6) ◽  
pp. 1134-1145
Author(s):  
F C Rector ◽  
N W Carter ◽  
D W Seldin
Keyword(s):  
Steady State ◽  
Carbonic Anhydrase ◽  
Proximal Tubule ◽  
Intravenous Injection ◽  
Distal Tubule ◽  
Ph Sensitive ◽  
Tubular Cells ◽  
Bicarbonate Reabsorption ◽  
Luminal Membrane ◽  
Distal Tubules

The mechanism of HCO3- reabsorption in proximal and distal tubules was examined in rats undergoing NaHCO3 diuresis. The steady-state intratubular pH was measured with pH-sensitive glass microelectrodes and compared with the equilibrium pH calculated from the HCO3- concentration of the tubular fluid (measured with quinhydrone electrodes) and plasma Pco2. In the proximal tubule the intratubular pH and the equilibrium pH were identical, indicating no accumulation of excess H2CO3. After inhibition of carbonic anhydrase, however, intratubular pH was significantly lower (0.85 pH U) than the equilibrium pH. It was concluded that HCO3- reabsorption in the proximal tubule was mediated by H+ secretion, but that carbonic anhydrase located in the luminal membrane of the cell prevented H2CO3 from accumulating in the tubular fluid. In the distal tubule the intratubular pH was 0.85 U lower than the equilibrium pH. This difference could be obliterated by an intravenous injection of carbonic anhydrase. It was concluded that HCO3- reabsorption in this segment was also accomplished by H+ secretion. The accumulation of excess H2CO3 in the tubular fluid indicated that, in contrast to the proximal tubule, carbonic anhydrase was not located in the luminal membrane of distal tubular cells.

scholarly journals Ca2+ transport by the luminal membrane of the distal nephron: action and interaction of protein kinases A and C

1997 ◽  
Vol 328 (2) ◽  
pp. 371-375 ◽  
Author(s):  
Georges HILAL ◽  
David CLAVEAU ◽  
Marie LECLERC ◽  
Michèle G. BRUNETTE
Keyword(s):  
Phospholipase C ◽  
Protein Kinases ◽  
Distal Tubule ◽  
High Concentration ◽  
Protein Kinase C Inhibitors ◽  
Luminal Membrane ◽  
Low Concentrations ◽  
Distal Tubules ◽  
High Concentrations

We previously reported that parathyroid hormone and calcitonin increase Ca2+ uptake by purified distal luminal membranes. This effect is mimicked by high concentrations of cAMP. However, both hormones stimulate adenylate cyclase and phospholipase C. The purpose of the present study was to investigate the role of the phospholipase C pathway in the hormone action, and the interrelationship between the two messengers. Distal tubules from rabbit kidneys were incubated with dibutyryl cAMP (dbcAMP) or PMA, or both, and Ca2+ uptake by purified luminal membranes was measured by the rapid filtration technique. Incubation of the distal tubules with 1 mM dbcAMP significantly increased Ca2+ transport by the luminal membranes. A dose-response curve showed a half-maximal stimulation with 0.82 mM dbcAMP. In contrast, treatment of the tubules with 10 nM, 100 nM or 1 μM PMA did not influence Ca2+ uptake by these membranes. However, the addition of 100 nM PMA to low concentrations of dbcAMP strongly increased this uptake. The presence of cAMP or protein kinase C inhibitors prevented the effects of either a high concentration of dbcAMP alone or a low concentration of dbcAMP combined with 100 nM PMA. Our laboratory has already reported that Ca2+ uptake by the distal luminal membranes displays two-component kinetics. dbcAMP increased the Vmax of the low-affinity component, whereas a combination of the two messengers stimulated the Vmax of both the low- and high-affinity components. From these results, we conclude that: (1) in the distal tubule cells, activation of both protein kinases A and C is necessary for the stimulation of Ca2+ transport by the luminal membrane; (2) the combined effect of protein kinases A and C involves both components of the Ca2+-transport kinetics.

THE EFFECT OF DAMAGE TO VARIOUS PARTS OF THE RENAL TUBULE ON THE EXCRETION OF PHOSPHATE BY THE DOG'S KIDNEY

1959 ◽  
Vol 37 (1) ◽  
pp. 103-111 ◽  
Author(s):  
T. F. Nicholson ◽  
G. W. Shepherd
Keyword(s):  
Proximal Tubule ◽  
Mercuric Chloride ◽  
Renal Tubule ◽  
Potassium Dichromate ◽  
Left Kidney ◽  
Distal Tubule ◽  
Proximal Tubules ◽  
Sodium Tartrate ◽  
Phosphate Excretion ◽  
Distal Tubules

The first third of the proximal tubules of the left kidney in dogs was damaged by the injection of 2.5 mg% potassium dichromate, the last two thirds by the injection of 0.5% sodium tartrate, and the distal tubules by the retrograde injection up the ureter of 0.05% mercuric chloride. Damage to the first third of the proximal tubule resulted in marked increase in phosphate excretion. Damage to the last two thirds of the proximal tubule had no significant effect on the output of phosphate. When the distal tubule was damaged the excretion of phosphate was greatly reduced. The results indicate that phosphate is reabsorbed in the first third of the proximal tubule and actively excreted by the distal tubule.

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