Regulation of sodium transport in M-1 cells

1998 ◽  
Vol 275 (6) ◽  
pp. F998-F1007 ◽  
Author(s):  
Nazih L. Nakhoul ◽  
Kathleen S. Hering-Smith ◽  
Cecilia T. Gambala ◽  
L. Lee Hamm
Keyword(s):  
Phorbol Esters ◽  
Collecting Duct ◽  
Cortical Collecting Duct ◽  
Acute Effects ◽  
Intracellular Ca ◽  
Epidermal Growth ◽  
Endogenous Protease ◽  
Free Media ◽  
Permeable Support

The M-1 cell line, derived from the mouse cortical collecting duct (CCD), is being used as a mammalian model of the CCD to study Na+ transport. The present studies aimed to further define the role of various hormones in affecting Na+ transport in M-1 cells grown in defined media. M-1 cells on permeable support, in serum-free media, developed amiloride-sensitive current 4–5 days after seeding. As expected for the involvement of epithelial Na+ channels, α-, β-, and γ-subunits of the epithelial Na+ channel were identified by RT-PCR. Either dexamethasone (Dex, 10–100 nM) or aldosterone (Aldo, 10−6–10−7M) for 24 h stimulated transport. Cells grown in the presence of Aldo and Dex had higher transport than with Dex alone. Spironolactone added to Dex media decreased transport. The acute effects of hormones reported to inhibit Na+ transport in CCD were also examined. Epidermal growth factor, phorbol esters, and increased intracellular Ca2+ with thapsigargin did not alter transport. Arginine vasopressin caused a transient increase in transport (probably Cl− secretion), which was not amiloride sensitive. Also, the protease inhibitor aprotinin decreased Na+ transport; in aprotinin-treated cells, trypsin stimulated transport. This study demonstrates that adrenal steroids (Dex > Aldo) stimulate Na+ transport in M-1 cells. At least part of this response may represent activation of mineralocorticoid receptors based on an additive effect of Dex and Aldo, as well as inhibition by spironolactone. Responses to immediate-acting hormones is limited. However, an endogenous protease activity, which activates Na+ transport, is present in these cells.

Polaris, a protein disrupted inorpkmutant mice, is required for assembly of renal cilium

2002 ◽  
Vol 282 (3) ◽  
pp. F541-F552 ◽  
Author(s):  
Bradley K. Yoder ◽  
Albert Tousson ◽  
Leigh Millican ◽  
John H. Wu ◽  
Charles E. Bugg ◽  
...  
Keyword(s):  
Primary Cilia ◽  
Collecting Duct ◽  
Physiological Role ◽  
Duct Cell ◽  
Cystic Kidney Disease ◽  
Cystic Kidney ◽  
Apical Surface ◽  
Cystic Disease ◽  
Cortical Collecting Duct

Cilia are organelles that play diverse roles, from fluid movement to sensory reception. Polaris, a protein associated with cystic kidney disease in Tg737°rpkmice, functions in a ciliogenic pathway. Here, we explore the role of polaris in primary cilia on Madin-Darby canine kidney cells. The results indicate that polaris localization and solubility change dramatically during cilia formation. These changes correlate with the formation of basal bodies and large protein rafts at the apical surface of the epithelia. A cortical collecting duct cell line has been derived from mice with a mutation in the Tg737 gene. These cells do not develop normal cilia, which can be corrected by reexpression of the wild-type Tg737 gene. These data suggest that the primary cilia are important for normal renal function and/or development and that the ciliary defect may be a contributing factor to the cystic disease in Tg737°rpkmice. Further characterization of these cells will be important in elucidating the physiological role of renal cilia and in determining their relationship to cystic disease.

Adenosine-stimulated Ca2+reabsorption is mediated by apical A1 receptors in rabbit cortical collecting system

1998 ◽  
Vol 274 (4) ◽  
pp. F736-F743 ◽  
Author(s):  
Joost G. J. Hoenderop ◽  
Anita Hartog ◽  
Peter H. G. M. Willems ◽  
René J. M. Bindels
Keyword(s):  
Collecting Duct ◽  
Cortical Collecting Duct ◽  
Concomitant Increase ◽  
Cgs 21680 ◽  
Kinase C ◽  
Intracellular Ca ◽  
Collecting Duct Cells ◽  
Camp Formation ◽  
Pkc Activation ◽  
Permeable Supports

Confluent monolayers of immunodissected rabbit connecting tubule and cortical collecting duct cells, cultured on permeable supports, were used to study the effect of adenosine on net apical-to-basolateral Ca2+ transport. Apical, but not basolateral, adenosine increased this transport dose dependently from 48 ± 3 to 110 ± 4 nmol ⋅ h−1 ⋅ cm−2. Although a concomitant increase in cAMP formation suggested the involvement of an A2 receptor, the A2 agonist CGS-21680 did not stimulate Ca2+ transport, while readily increasing cAMP. By contrast, the A1 agonist N 6-cyclopentyladenosine (CPA) maximally stimulated Ca2+transport without significantly affecting cAMP. Adenosine-stimulated transport was effectively inhibited by the A1 antagonist 1,3-dipropyl-8-cyclopenthylxanthine but not the A2 antagonist 3,7-dimethyl-1-propargylxanthine, providing additional evidence for the involvement of an A1 receptor. Both abolishment of the adenosine-induced transient increase in intracellular Ca2+ concentration by 1,2-bis(2-aminophenoxy)ethane- N, N, N′, N′-tetraacetic acid and downregulation of protein kinase C (PKC) by prolonged phorbol ester treatment were without effect on adenosine-stimulated Ca2+ transport. The data presented suggest that adenosine interacts with an apical A1 receptor to stimulate Ca2+ transport via a hitherto unknown pathway that does not involve cAMP formation, PKC activation, and/or Ca2+ mobilization.

Role of AQP2 during apoptosis in cortical collecting duct cells

2009 ◽  
Vol 101 (4) ◽  
pp. 237-250 ◽  
Author(s):  
Pilar Flamenco ◽  
Luciano Galizia ◽  
Valeria Rivarola ◽  
Juan Fernandez ◽  
Paula Ford ◽  
...  
Keyword(s):  
Collecting Duct ◽  
Cortical Collecting Duct ◽  
Duct Cells ◽  
Collecting Duct Cells

Nifedipine-activated Ca2+ permeability in newborn rat cortical collecting duct cells in primary culture

2001 ◽  
Vol 280 (5) ◽  
pp. C1193-C1203 ◽  
Author(s):  
Laura Valencia ◽  
Michel Bidet ◽  
Sonia Martial ◽  
Elsa Sanchez ◽  
Estela Melendez ◽  
...  
Keyword(s):  
Primary Culture ◽  
Transient Receptor Potential ◽  
Collecting Duct ◽  
Primary Cultures ◽  
Receptor Potential ◽  
Cortical Collecting Duct ◽  
Newborn Rat ◽  
Adult Rat ◽  
Intracellular Ca ◽  
Transient Receptor

To characterize Ca2+ transport in newborn rat cortical collecting duct (CCD) cells, we used nifedipine, which in adult rat distal tubules inhibits the intracellular Ca2+concentration ([Ca2+]i) increase in response to hormonal activation. We found that the dihydropyridine (DHP) nifedipine (20 μM) produced an increase in [Ca2+]i from 87.6 ± 3.3 nM to 389.9 ± 29.0 nM in 65% of the cells. Similar effects of other DHP (BAY K 8644, isradipine) were also observed. Conversely, DHPs did not induce any increase in [Ca2+]i in cells obtained from proximal convoluted tubule. In CCD cells, neither verapamil nor diltiazem induced any rise in [Ca2+]i. Experiments in the presence of EGTA showed that external Ca2+ was required for the nifedipine effect, while lanthanum (20 μM), gadolinium (100 μM), and diltiazem (20 μM) inhibited the effect. Experiments done in the presence of valinomycin resulted in the same nifedipine effect, showing that K+ channels were not involved in the nifedipine-induced [Ca2+]i rise. H2O2also triggered [Ca2+]i rise. However, nifedipine-induced [Ca2+]i increase was not affected by protamine. In conclusion, the present results indicate that 1) primary cultures of cells from terminal nephron of newborn rats are a useful tool for investigating Ca2+transport mechanisms during growth, and 2) newborn rat CCD cells in primary culture exhibit a new apical nifedipine-activated Ca2+ channel of capacitive type (either transient receptor potential or leak channel).

Evidence of corticosteroid action along the nephron

1984 ◽  
Vol 246 (2) ◽  
pp. F111-F123 ◽  
Author(s):  
D. Marver
Keyword(s):  
Collecting Duct ◽  
Type I ◽  
Type Ii ◽  
Cortical Collecting Duct ◽  
Distal Nephron ◽  
Type Iii ◽  
Collecting Ducts ◽  
Collecting Tubule ◽  
Cortical Collecting Tubule

The kidney contains three classes of corticosteroid-binding proteins receptors. They include a mineralocorticoid-specific (Type I), a glucocorticoid-specific (Type II), and a corticosterone-specific (Type III) site. The Type I and Type III sites roughly parallel each other along the nephron, with maximal binding occurring in the late distal convoluted or connecting segment and the cortical and medullary collecting ducts. Type II sites occur throughout the nephron, with maximal concentrations appearing in the proximal tubule and the late distal convoluted-cortical collecting duct region. The function of the Type I sites in the connecting segment is unclear since chronic mineralocorticoid therapy does not influence the potential difference in this segment as it does in the cortical collecting tubule. Furthermore, the specific role of Type II versus Type III sites in the distal nephron is unknown. Finally, the possible influence of sodium on both latent and steroid-induced renal cortical and medullary Na-K-ATPase is discussed.

Response of rat inner medullary collecting duct to epidermal growth factor

1989 ◽  
Vol 256 (6) ◽  
pp. F1117-F1124 ◽  
Author(s):  
R. C. Harris
Keyword(s):  
Growth Factor ◽  
Binding Sites ◽  
Collecting Duct ◽  
Affinity Binding ◽  
Inner Medullary Collecting Duct ◽  
Duct Cells ◽  
Epidermal Growth ◽  
Collecting Duct Cells ◽  
Medullary Collecting Duct

Urine is an abundant source of epidermal growth factor (EGF) and prepro-EGF has been localized to the thick ascending limb and distal convoluted tubule of the kidney. However, the functional role of EGF in the kidney is poorly understood. Determination of EGF receptors and functional responses to EGF in intrarenal structures distal to the site of renal EGF production may prove critical to our understanding of the role of this peptide. These studies were designed to investigate the response to EGF of rat inner medullary collecting duct cells in culture and in freshly isolated suspensions. Primary cultures of inner medullary collecting duct cells demonstrated equilibrium binding of 125I-labeled EGF at 4 and 23 degrees C. At 23 degrees C, there was 89 +/- 1% specific binding (n = 30). Scatchard analysis of 125I-EGF binding suggested the presence of both high-affinity binding with a dissociation constant (Kd) of 5 X 10(-10) M and maximal binding sites (Ro) of 2.7 X 10(3) binding sites/cell and low-affinity binding, with Kd of 8.3 X 10(-9) M and Ro of 1.8 X 10(4) binding sites/cell. Bound EGF, 68 +/- 3%, was internalized by 45 min. EGF binding was not inhibited by antidiuretic hormone, atrial natriuretic peptide or bradykinin at 23 degrees C, but there was concentration-dependent inhibition of binding by transforming growth factor-alpha. Incubation with phorbol myristate acetate decreased 125I-EGF binding in a concentration-dependent manner. 125I-EGF binding was also demonstrated in freshly isolated suspensions of rat inner medullary collecting duct cells.(ABSTRACT TRUNCATED AT 250 WORDS)

EGF and PGE2 inhibit rabbit CCD Na+ transport by different mechanisms: PGE2 inhibits Na(+)-K+ pump

1993 ◽  
Vol 264 (4) ◽  
pp. F670-F677 ◽  
Author(s):  
D. H. Warden ◽  
J. B. Stokes
Keyword(s):  
Apical Membrane ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Membrane Conductance ◽  
Membrane Voltage ◽  
Na Channel ◽  
Cortical Collecting Duct ◽  
Na Transport ◽  
Flux Measurements ◽  
Epidermal Growth

The rabbit cortical collecting duct absorbs Na+ by a transport system comprised of an apical membrane Na+ channel and a basolateral membrane Na(+)-K(+)-adenosinetriphosphatase. The rate of Na+ absorption across this epithelium is acutely inhibited by several hormones and autacoids including epidermal growth factor (EGF) and prostaglandin E2 (PGE2). We used electrophysiological analysis to determine which Na+ transport mechanism is primarily regulated in response to EGF and PGE2. We used concentrations of EGF and PGE2 that inhibited Na+ absorption to a comparable degree. We assessed the effects of these agents on Na+ transport primarily by the calculated equivalent current; the validity of this indicator was verified using simultaneous tracer flux measurements. EGF and PGE2 had different effects on the intracellular electrophysiological parameters. EGF (in the presence of a cyclooxygenase inhibitor) hyperpolarized the apical membrane voltage in a manner analogous to the Na(+)-channel blocker amiloride, reduced the transepithelial conductance, and increased the fractional resistance of the apical membrane. In comparison, PGE2 depolarized the apical membrane voltage in a manner analogous to the Na(+)-K+ pump inhibitor ouabain, and caused no significant changes in transepithelial conductance or apical membrane conductance. The finding that EGF hyperpolarized the apical membrane indicates that this agent attenuates Na+ absorption by reducing apical Na+ entry due to a decrease in the magnitude of the apical membrane Na+ conductance. In contrast, the electrophysiological changes produced by PGE2 indicate primary inhibition of the basolateral Na(+)-K+ pump following PGE2 treatment.

Adaptation to alkalosis induces cell cycle delay and apoptosis in cortical collecting duct cells: Role of aquaporin-2

2010 ◽  
Vol 224 (2) ◽  
pp. 405-413 ◽  
Author(s):  
Valeria Rivarola ◽  
Pilar Flamenco ◽  
Luciana Melamud ◽  
Luciano Galizia ◽  
Paula Ford ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Collecting Duct ◽  
Cortical Collecting Duct ◽  
Cell Cycle Delay ◽  
Aquaporin 2 ◽  
Duct Cells ◽  
Collecting Duct Cells

Deoxycorticosterone-stimulated bicarbonate secretion in rabbit cortical collecting ducts: effects of luminal chloride removal and in vivo acid loading

1985 ◽  
Vol 249 (2) ◽  
pp. F205-F212 ◽  
Author(s):  
J. Garcia-Austt ◽  
D. W. Good ◽  
M. B. Burg ◽  
M. A. Knepper
Keyword(s):  
Collecting Duct ◽  
High Rate ◽  
Bicarbonate Secretion ◽  
Cortical Collecting Duct ◽  
Acid Base ◽  
Urinary Ph ◽  
Collecting Ducts ◽  
Acid Loading

To assess the role of cortical collecting duct bicarbonate secretion in the regulation of net acid excretion, we have sought to identify what factors influence the secretion rate. Net and unidirectional bicarbonate fluxes were measured in isolated perfused cortical collecting ducts from deoxycorticosterone-treated rabbits. The collecting ducts secreted bicarbonate at 11-24 pmol X mm-1 X min-1, confirming the high rate seen in earlier studies. Oral acid loading (50 mM NH4Cl drinking water) completely inhibited the net bicarbonate secretion. The bath-to-lumen flux was markedly reduced with acid loading, but the lumen-to-bath flux changed very little. In tubules from rabbits treated with deoxycorticosterone (but not NH4Cl), luminal chloride replacement with either sulfate or gluconate completely and reversibly inhibited the net bicarbonate secretion. The bath-to-lumen flux was greatly inhibited, but there was little change in the lumen-to-bath flux. We conclude: 1) High rates of bicarbonate secretion can be induced in rabbit cortical collecting ducts by chronic treatment of the animals with deoxycorticosterone. 2) When deoxycorticosterone-treated rabbits were made acidotic by oral administration of NH4Cl, the bicarbonate secretion was prevented, indicating that the systemic acid-base state of the animal may be an important factor regulating bicarbonate secretion. 3) Replacement of chloride in the lumen with sulfate inhibits bicarbonate secretion in the cortical collecting duct, an effect which may explain in part the decrease in urinary pH in response to sulfate infusions in mineralocorticoid-stimulated animals.

Stimulation of total CO2 flux by 10% CO2 in rabbit CCD: role of an apical Sch-28080- and Ba-sensitive mechanism

1994 ◽  
Vol 267 (1) ◽  
pp. F114-F120 ◽  
Author(s):  
X. Zhou ◽  
C. S. Wingo
Keyword(s):  
Collecting Duct ◽  
Co2 Flux ◽  
K Channel ◽  
Co2 Absorption ◽  
Cortical Collecting Duct ◽  
Atpase Inhibitor ◽  
Contrast Exposure ◽  
Stimulation Of

These studies examine the effect of ambient PCO2 on net bicarbonate (total CO2) absorption by the in vitro perfused cortical collecting duct (CCD) from K-replete rabbits and the mechanism responsible for this effect. Exposure to 10% CO2 increased net bicarbonate flux (total CO2 flux, JtCO2) by 1.8-fold (P < 0.005), and this effect was inhibited by luminal 10 microM Sch-28080, an H-K-adenosinetriphosphatase (H-K-ATPase) inhibitor. In contrast, exposure to 10% CO2 significantly decreased Rb efflux, and this decrement in Rb efflux was blocked by luminal 2 mM Ba, a K channel blocker. Thus transepithelial tracer Rb flux did not increase upon exposure to 10% CO2 as we have observed in this segment under K-restricted conditions. The observation that 10% CO2 increased net bicarbonate absorption without a change in absorptive Rb flux suggested that 10% CO2 increased apical K recycling. To test this hypothesis, we examined whether luminal Ba inhibited the stimulation of luminal acidification induced by 10% CO2. If apical K exit were necessary for full activation of proton secretion, then inhibiting K exit should indirectly affect the stimulation of JtCO2 by 10% CO2. In fact, the effect of 10% CO2 on JtCO2 in the presence of 2 mM luminal Ba was quantitatively indistinguishable from the effect of 10% CO2 on JtCO2 in the presence of 10 microM luminal Sch-28080.(ABSTRACT TRUNCATED AT 250 WORDS)

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