scholarly journals Angiotensin II and Renal Tubular Ion Transport

2005 ◽  
Vol 5 ◽  
pp. 680-690 ◽  
Author(s):  
Patricia Valles ◽  
Jan Wysocki ◽  
Daniel Batlle
Keyword(s):  
Angiotensin Ii ◽  
Atpase Activity ◽  
Collecting Duct ◽  
Cortical Collecting Duct ◽  
Water Excretion ◽  
Bicarbonate Reabsorption ◽  
Sodium Dependent ◽  
Collecting Tubule

Angiotensin II, a potent vasoconstrictor, also participates in the regulation of renal sodium and water excretion, not only via a myriad of effects on renal hemodynamics, glomerular filtration rate, and regulation of aldosterone secretion, but also via direct effects on renal tubule transport. In addition, angiotensin II stimulates H+secretion and HCO3–reabsorption in both proximal and distal tubules and regulates H+-ATPase activity in intercalated cells of the collecting tubule. Different results regarding the effect of angiotensin II on bicarbonate reabsorption and proton secretion have been reported at the functional level, depending on the angiotensin II concentration and tubule segment studied. It is likely that interstitial angiotensin II is more important in regulating hemodynamic and transport functions than circulating angiotensin II. In proximal tubules, stimulation of bicarbonate reabsorption, Na+/H+-exchange, and Na+/HCO3–cotransport has been found using low concentrations (<10–9M), while inhibition of bicarbonate reabsorption has been documented using concentrations higher than 10–8M. Evidence for the regulation of H+-ATPase activityin vivoandin vitroby trafficking/exocytosis has been provided. An additional level of H+-ATPase regulation via protein synthesis may be important as well. Recently, we have shown that both aldosterone and angiotensin II provide such a mechanism of regulationin vivoat the level of the medullary collecting tubule. Interestingly, in this part of the nephron, the effects of aldosterone and angiotensin II are not sodium dependent, whereas in the cortical collecting duct, both aldosterone and angiotensin II, by contrast, affect H+secretion by sodium-dependent mechanisms.

Effect of vasopressin on Na+-K+-ATPase activity in rat cortical collecting duct

1987 ◽  
Vol 253 (5) ◽  
pp. F874-F879 ◽  
Author(s):  
K. Tomita ◽  
A. Owada ◽  
Y. Iino ◽  
N. Yoshiyama ◽  
T. Shiigai
Keyword(s):  
Atpase Activity ◽  
Time Course ◽  
Collecting Duct ◽  
Cortical Collecting Duct ◽  
Henle's Loop ◽  
K Secretion ◽  
Medullary Collecting Duct ◽  
Hydrolysis Of

Vasopressin (V) causes a sustained increase in Na reabsorption and K secretion in isolated cortical collecting ducts (CCD) from rats. Because increased Na reabsorption may be associated with increased Na+-K+-ATPase activity, we investigated effects of V, given either in vivo or in vitro, on Na+-K+-ATPase activity in isolated nephron segments of rats. Na+-K+-ATPase activities were measured by coupling the hydrolysis of ATP to the production of a fluorescent nucleotide. In addition to CCD, other microdissected structures were medullary thick ascending limbs of Henle's loop, cortical thick ascending limbs of Henle's loop, and outer medullary collecting duct. To determine the time course of the response, Na+-K+-ATPase activities were measured in CCD 1 h, 3 h, 1 day, 3 days, and 7 days after intramuscular administrations of V. There was a significant increase in Na+-K+-ATPase activity in CCD after in vivo V administration for 7 days but not in any other segment. The activities increased after 3 days of administration of V. For in vitro experiments, CCD were incubated with 10(-6) M V for 1-3 h. Na+-K+-ATPase activities did not change after 1- or 3-h exposure of V in CCD in vitro. We conclude that prolonged V administration in vivo increases Na+-K+-ATPase activity in CCD. Because, in vitro exposure to V does not increase Na+-K+-ATPase activity, we conclude that rapid V-dependent increases in Na and K transport previously demonstrated in isolated perfused tubules are not dependent on a change in maximal Na+-K+-ATPase activity.

Na-K-ATPase activity along the rabbit, rat, and mouse nephron

1979 ◽  
Vol 237 (2) ◽  
pp. F114-F120 ◽  
Author(s):  
A. I. Katz ◽  
A. Doucet ◽  
F. Morel
Keyword(s):  
Atpase Activity ◽  
Thick Ascending Limb ◽  
Sensitivity Limit ◽  
Henle's Loop ◽  
Collecting Tubule ◽  
Pars Recta ◽  
Hydrolysis Of ◽  
Total Enzyme

Na-K-ATPase activity along the rabbit, rat, and mouse nephron was determined with a micromethod that measures directly labeled phosphate released by the hydrolysis of [gamma-32P]ATP. Na-K-ATPase activity was highest in the rat, intermediate in the mouse, and lowest in the rabbit nephron. With the exception of rabbit cortical thick ascending limb, the enzyme profile was similar in the three species: Na-K-ATPase activity per millimeter tubule length was highest in the distal convoluted tubule and thick ascending limb of Henle's loop, intermediate in the proximal convoluted tubule, and lowest in the pars recta and collecting tubule. The enzyme was present in the thin limbs of Henle's loop, but its activity was very low and measurements were close to the sensitivity limit of the method. Both the absolute activity and the fraction of the total enzyme represented by Na-K-ATPase were severalfold higher than in kidney homogenates. Finally, the Na-K-ATPase activity measured in certain segments of the rat and rabbit nephron in this study seems sufficient to account in theory for the active component of the net sodium transport found in the corresponding region of the nephron with either in vivo or in vitro single tubule microperfusion techniques.

scholarly journals Cell-specific qRT-PCR of renal epithelial cells reveals a novel innate immune signature in murine collecting duct

2018 ◽  
Vol 315 (4) ◽  
pp. F812-F823 ◽  
Author(s):  
Vijay Saxena ◽  
David S. Hains ◽  
John Ketz ◽  
Melinda Chanley ◽  
John D. Spencer ◽  
...  
Keyword(s):  
Urinary Tract ◽  
Mrna Expression ◽  
Collecting Duct ◽  
Immune Defense ◽  
Innate Immune ◽  
Targeted Analysis ◽  
Collecting Tubule ◽  
Tubule Cells

The urinary tract is usually culture negative despite its close proximity to microbial flora. The precise mechanism by which the kidneys and urinary tract defends against infection is not well understood. The initial kidney cells to encounter ascending pathogens are the collecting tubule cells that consist of principal cells (PCs) that express aquaporin 2 (AQP2) and intercalated cells (ICs) that express vacuolar H+-ATPase (V-ATPase, B1 subunit). We have previously shown that ICs are involved with the human renal innate immune defense. Here we generated two reporter mice, VATPase B1-cre+tdT+mice to fluorescently label ICs and AQP2-cre+tdT+mice to fluorescently label PCs, and then performed flow sorting to enrich PCs and ICs for analysis. Isolated ICs and PCs along with proximal tubular cells were used to measure antimicrobial peptide (AMP) mRNA expression. ICs and PCs were significantly enriched for AMPs. Isolated ICs responded to uropathogenic Escherichia coli (UPEC) challenge in vitro and had higher RNase4 gene expression than control while both ICs and PCs responded to UPEC challenge in vivo by upregulating Defb1 mRNA expression. To our knowledge, this is the first report of isolating murine collecting tubule cells and performing targeted analysis for multiple classes of AMPs.

Short-term effect of aldosterone on NEM-sensitive ATPase in rat collecting tubule

1989 ◽  
Vol 257 (2) ◽  
pp. F177-F181 ◽  
Author(s):  
C. Khadouri ◽  
S. Marsy ◽  
C. Barlet-Bas ◽  
A. Doucet
Keyword(s):  
Atpase Activity ◽  
Affinity Constant ◽  
Short Term ◽  
Collecting Tubule ◽  
Lag Period ◽  
In Vitro Effects ◽  
Collecting Tubules

Because previous studies indicated that in the collecting tubule, N-ethylmaleimide (NEM)-sensitive ATPase, the biochemical equivalent of the proton pump, is controlled by mineralocorticoids in the long term, the present study was designed to investigate whether such control also exists in the short term. Therefore we investigated the in vivo and in vitro effects of aldosterone on the enzyme activity in cortical and outer medullary collecting tubules (CCT and MCT, respectively) from adrenalectomized rats. Administration of aldosterone (10 micrograms/kg body wt) markedly stimulated NEM-sensitive ATPase activity in the CCT and MCT within 3 h. Similarly, incubating CCT or MCT for 3 h in the presence of 10(-8) M aldosterone enhanced NEM-sensitive ATPase activity up to values similar to those previously measured in the corresponding nephron segments of normal rats. In vitro stimulation of NEM-sensitive ATPase was dose dependent in regard to aldosterone (apparent affinity constant approximately 10(-9) M), appeared after a 30-min lag period, and reached its maximum after 2-2.5 h. Finally, actinomycin D and cycloheximide totally abolished the in vitro action of aldosterone, demonstrating the involvement of protein synthesis in this process.

scholarly journals Uroguanylin inhibits H-ATPase activity and surface expression in renal distal tubules by a PKG-dependent pathway

2014 ◽  
Vol 307 (6) ◽  
pp. C532-C541 ◽  
Author(s):  
Vanessa da Silva Lima ◽  
Renato O. Crajoinas ◽  
Luciene R. Carraro-Lacroix ◽  
Alana N. Godinho ◽  
João L. G. Dias ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Distal Tubule ◽  
Surface Expression ◽  
Inhibitory Effect ◽  
Camp Content ◽  
Bicarbonate Reabsorption ◽  
Guanylate Cyclase C ◽  
Dependent Pathway

Cumulative evidence suggests that guanylin peptides play an important role on electrolyte homeostasis. We have previously reported that uroguanylin (UGN) inhibits bicarbonate reabsorption in a renal distal tubule. In the present study, we tested the hypothesis that the bicarbonaturic effect of UGN is at least in part attributable to inhibition of H+-ATPase-mediated hydrogen secretion in the distal nephron. By in vivo stationary microperfusion experiments, we were able to show that UGN inhibits H+-ATPase activity by a PKG-dependent pathway because KT5823 (PKG inhibitor) abolished the UGN effect on distal bicarbonate reabsorption and H89 (PKA inhibitor) was unable to prevent it. The in vivo results were confirmed by the in vitro experiments, where we used fluorescence microscopy to measure intracellular pH (pHi) recovery after an acid pulse with NH4Cl. By this technique, we observed that UGN and 8 bromoguanosine-cGMP (8Br-cGMP) inhibited H+-ATPase-dependent pHi recovery and that the UGN inhibitory effect was abolished in the presence of the PKG inhibitor. In addition, by using RT-PCR technique, we verified that Madin-Darby canine kidney (MDCK)-C11 cells express guanylate cyclase-C. Besides, UGN stimulated an increase of both cGMP content and PKG activity but was unable to increase the production of cellular cAMP content and PKA activity. Furthermore, we found that UGN reduced cell surface abundance of H+-ATPase B1 subunit in MDCK-C11 and that this effect was abolished by the PKG inhibitor. Taken together, our data suggest that UGN inhibits H+-ATPase activity and surface expression in renal distal cells by a cGMP/PKG-dependent pathway.

Cellular actions of cAMP on HCO3(-)-secreting cells of rabbit CCD: dependence on in vivo acid-base status

1994 ◽  
Vol 266 (4) ◽  
pp. F528-F535 ◽  
Author(s):  
C. Emmons ◽  
J. B. Stokes
Keyword(s):  
Anion Exchanger ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Disulfonic Acid ◽  
Intercalated Cells ◽  
Cortical Collecting Duct ◽  
Acid Base ◽  
Acid Base Status

HCO3- secretion by cortical collecting duct (CCD) occurs via beta-intercalated cells. In vitro CCD HCO3- secretion is modulated by both the in vivo acid-base status of the animal and by adenosine 3',5'-cyclic monophosphate (cAMP). To investigate the mechanism of cAMP-induced HCO3- secretion, we measured intracellular pH (pHi) of individual beta-intercalated cells of CCDs dissected from alkali-loaded rabbits perfused in vitro. beta-Intercalated cells were identified by demonstrating the presence of an apical anion exchanger (cell alkalinization in response to removal of lumen Cl-). After 180 min of perfusion to permit decrease of endogenous cAMP, acute addition of 0.1 mM 8-bromo-cAMP or 1 microM isoproterenol to the bath caused a transient cellular alkalinization (> 0.20 pH units). In the symmetrical absence of either Na+, HCO3-, or Cl-, cAMP produced no change in pHi. Basolateral dihydrogen 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (0.1 mM) for 15 min before cAMP addition also prevented this alkalinization. In contrast to the response of cells from alkali-loaded rabbits, addition of basolateral cAMP to CCDs dissected from normal rabbits resulted in an acidification of beta-intercalated cells (approximately 0.20 pH units). The present studies demonstrate the importance of the in vivo acid-base status of the animal in the regulation of CCD HCO3- secretion by beta-intercalated cells. The results identify the possible existence of a previously unrecognized Na(+)-dependent Cl-/HCO3- exchanger on the basolateral membrane of beta-intercalated cells in alkali-loaded rabbits.

H(+)-K(+)-ATPase activity in rat collecting duct segments

1992 ◽  
Vol 262 (4) ◽  
pp. F692-F695 ◽  
Author(s):  
J. D. Gifford ◽  
L. Rome ◽  
J. H. Galla
Keyword(s):  
Atpase Activity ◽  
Marked Decrease ◽  
Collecting Duct ◽  
Intercalated Cells ◽  
Cortical Collecting Duct ◽  
Acid Base ◽  
Medullary Collecting Duct ◽  
Gastric Proton Pump

Previous studies have suggested the presence of an H(+)-K(+)-ATPase in rat cortical and medullary intercalated cells with similar properties to the gastric proton pump. The purpose of this study was to determine the functional contribution of an H(+)-K(+)-adenosinetriphosphatase(ATPase) to total CO2 (tCO2) transport along the rat collecting duct. After baseline determination of tCO2 transport in isolated perfused collecting duct segments, Sch 28080 (10 microM) was added to either the perfusate or bath. When Sch 28080 was added to the perfusate, there was no effect in the cortical collecting duct (CCD, 20.8 +/- 6.7 vs. 25.3 + 3.0 pmol.mm-1.min-1), but a marked decrease in tCO2 absorption was effected in both the outer medullary (OMCD, 37.6 + 6.2 vs. 10.7 +/- 4.1 pmol.mm-1.min-1) and initial inner medullary collecting duct (IMCD1, 34.4 +/- 8.1 vs. 16.2 +/- 5.6 pmol.mm-1.min-1). In the CCD from rats with acute alkalosis in vivo, Sch 28080 added to the bath inhibited tCO2 secretion in the CCD (-17.1 +/- 4.4 vs 3.5 + 3.3 pmol.mm-1.min-1). These findings suggest that 1) H(+)-K(+)-ATPase is important in tCO2 absorption in the OMCD and IMCD1 and in tCO2 secretion in the CCD, 2) HCO3(-)-absorbing intercalated cells differ functionally in the cortex and medulla, 3) HCO3- secretion is not the reverse process of HCO3- absorption in the CCD, and 4) H(+)-K(+)-ATPase is important in distal acidification under normal and altered acid-base conditions.

Phosphate transport by isolated rabbit cortical collecting tubule

1980 ◽  
Vol 238 (5) ◽  
pp. F358-F362
Author(s):  
R. A. Peraino ◽  
W. N. Suki
Keyword(s):  
Specific Activity ◽  
Collecting Duct ◽  
Phosphate Transport ◽  
Cortical Collecting Duct ◽  
Renal Handling ◽  
Bathing Medium ◽  
Collecting Tubule ◽  
Absorptive Flux ◽  
Cortical Collecting Tubule

Renal handling of phosphate occurs in the proximal convoluted tubule. Absorption of this anion also occurs in the pars recta and distal convoluted tubule, the latter a structurally and functionally diverse segment. The purpose of the present investigation was to examine phosphate transport by the cortical collecting duct of the rabbit. Segments of cortical collecting tubule, beyond the last cortical branch, were isolated and perfused in vitro with an artificial solution simulating plasma as the perfusing and bathing medium. The perfusion solution contained either 3 or 25 mM bicarbonate. Net phosphate transport was measured using 32P as the radionuclide tracer, with identical specific activity in perfusing and bathing solutions. A net absorptive flux for phosphate was demonstrated, amounting to 2-3% of the delivered load. In addition, this absorptive flux was linearly related to perfusion rate and, thus, delivered load, but independent of the lumen bicarbonate concentration or pH.

scholarly journals Effects of ammonia on bicarbonate transport in the cortical collecting duct

2000 ◽  
Vol 278 (2) ◽  
pp. F219-F226 ◽  
Author(s):  
Amy E. Frank ◽  
Charles S. Wingo ◽  
I. David Weiner
Keyword(s):  
Collecting Duct ◽  
Potassium Transport ◽  
Bicarbonate Transport ◽  
Cortical Collecting Duct ◽  
Intracellular Acidification ◽  
Bicarbonate Reabsorption ◽  
Atpase Inhibitors ◽  
Collecting Ducts ◽  
Stimulation Of

Both acidosis and hypokalemia stimulate renal ammoniagenesis, and both regulate urinary proton and potassium excretion. We hypothesized that ammonia might play an important role in this processing by stimulating H+-K+-ATPase-mediated ion transport. Rabbit cortical collecting ducts (CCD) were studied using in vitro microperfusion, bicarbonate reabsorption was measured using microcalorimetry, and intracellular pH (pHi) was measured using the fluorescent, pH-sensitive dye, 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). Ammonia caused a concentration-dependent increase in net bicarbonate reabsorption that was inhibited by luminal addition of either of the H+-K+-ATPase inhibitors, Sch-28080 or ouabain. The stimulation of net bicarbonate reabsorption was not mediated through apical H+-ATPase, basolateral Na+-K+-ATPase, or luminal electronegativity. Although ammonia caused intracellular acidification, similar changes in pHi induced by inhibiting basolateral Na+/H+ exchange did not alter net bicarbonate reabsorption. We conclude that ammonia regulates CCD proton and potassium transport, at least in part, by stimulating apical H+-K+-ATPase.

1,25(OH)2D3 binding along the rat nephron: autoradiographic study in isolated tubular segments

1985 ◽  
Vol 248 (2) ◽  
pp. F296-F307 ◽  
Author(s):  
C. Manillier ◽  
N. Farman ◽  
J. P. Bonjour ◽  
J. P. Bonvalet
Keyword(s):  
Binding Sites ◽  
Specific Binding ◽  
Collecting Duct ◽  
Distal Tubule ◽  
Autoradiographic Study ◽  
Cortical Collecting Duct ◽  
Dihydroxyvitamin D3 ◽  
Collecting Tubule ◽  
Autoradiographic Technique

1,25-dihydroxyvitamin D3 [1,25(OH)2D3] binding sites were studied along the nephron of rats. The animals were pretreated with the diphosphonate EHDP at doses that inhibit the endogenous production of 1,25(OH)2D3. A dry film autoradiographic technique was applied to tubular segments isolated by microdissection from kidneys incubated in vitro with various concentrations (0.2-12 nM) of [3H]1,25(OH)2D3 in the presence or absence of an excess unlabeled hormone (X200) in order to determine specific binding. Total, nonspecific, and specific labeling were quantified by silver grain counting over cytoplasmic and nuclear areas. Specific nuclear labeling appeared in the cortical ascending limb and papillary collecting tubule at 1 nM. In the distal tubule and, to a lesser extent, in the cortical collecting tubule a specific nuclear labeling was also present, but only at higher concentrations. No specific nuclear labeling was detected in the proximal tubule. All along the nephron, a significant and nonspecific labeling was observed in the cytoplasm, either alone or superimposed over the specific nuclear labeling. In conclusion 1,25(OH)2D3 specific binding sites appear to be localized mainly in the cortical ascending limb of the loop of Henle, in the distal and cortical collecting duct, and in the papillary collecting duct.

Sign in / Sign up

Export Citation Format

Share Document