Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P41181 (collecting duct)
 5,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have reported that in the rabbit cortical collecting duct (CCD) we can identify electrophysiologically three distinct cell types; the collecting duct (CD) cell and the alpha- and beta-intercalated (IC) cell. To further characterize the Cl- transport properties of each cell type, we examined the interaction between Cl- and other halogens or SCN- in the isolated and perfused CCD by intracellular microelectrode impalement. The rapid depolarization of the basolateral membrane potential (VB) caused by replacement of bath Cl- with each anion revealed that the sequences of apparent halogen selectivity for the basolateral Cl- conductance were similar in all three cell types. The ranking of Cl- > Br- > F- > I- corresponds to the sequence 5 of Eisenman's series, indicating "strong" interaction of the anions with the selectivity site. The basolateral Cl- conductance of these three cell types may share common characteristics, although I- permeability is less in IC cells than in CD cells. Hyperpolarization of the basolateral membrane of the beta-IC cell upon reduction of luminal Cl- reflects alterations in either Cl- entry across the apical membrane, or Cl- exit across the basolateral membrane, or both. Luminal Cl- replacement with each anion showed that the sequence of the hyperpolarization of the basolateral membrane was I- >> cyclamate = SCN- > F- > Br-, suggesting that I-inhibits either apical Cl- entry or basolateral Cl- exit. On the other hand, in the CD cell reduction of the perfusate Cl- by replacement with each anion caused the basolateral membrane to hyperpolarize with a different ranking: cyclamate = F- > I- = SCN- > Br-.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Interaction of Cl- and other halogens with Cl- transport systems in rabbit cortical collecting duct. 144 75

Large vacuoles form in the renal collecting duct following the onset of antidiuretic hormone (ADH)-stimulated water reabsorption. The aim of the present study was to test two alternative hypotheses regarding the origins of these structures: (1) the vacuoles constitute basilar, extracellular spaces that dilate as water flows through these spaces from cells into the peritubular compartment; or (2) the vacuoles represent intracellular, endocytic compartments that dilate during water reabsorption due to enhanced fluid phase endocytosis. Fluorescence-digital imaging microscopy was used to visualize the uptake into vacuoles of a hydrophilic fluorochrome (6 methoxy-N-[3 sulfopropyl] quinolinium) whose fluorescence is markedly quenched by halides. During their formation, most vacuoles (67%) accumulated the fluorochrome from the peritubular bath and trapped the dye well after (greater than 60 min) washing it from the bath. The spatial pattern of fluorescence within individual vacuoles indicated that the dye was trapped within these structures as a fluid-phase marker and was not bound to the vacuole margins. The fluorescence of dye trapped within vacuoles was virtually unaltered by changes in peritubular Cl- or Br- concentration that elicit dramatic quenching of dye-fluorescence in bulk solution, as expected if there exists a high diffusion resistance between the interiors of these structures and the peritubular space. These results indicate that most ADH-induced vacuoles represent endocytic compartments that are not directly connected to the extracellular space.
 ...
PMID:Diffusion resistances between ADH-induced vacuoles and the extracellular space in rabbit collecting duct: evidence that most vacuoles are intracellular, endocytic compartments. 200 48

Atrial natriuretic peptides (ANP) stimulate renal Na+ excretion by poorly understood mechanisms, possibly involving direct inhibition of Na+ transport in the renal medulla. We have previously shown that human ANP 4-28 (hANP) inhibits Na+ entry-dependent O2 consumption (QO2) in rabbit inner medullary collecting duct (IMCD) cells. Because ANP actions in other tissues appear to be mediated by guanosine 3',5'-cyclic monophosphate (cGMP), the present studies examined the role of cyclic nucleotides in IMCD cell responses to ANP. 8-Bromo-cGMP (8-BrcGMP) diminished QO2 by 23.5 +/- 1.2% (SE) in IMCD cells but had no effect in cells derived from outer medullary collecting duct (OMCD); dibutyryl-adenosine 3',5'-cyclic monophosphate (cAMP) was without effect in IMCD cells. The inhibitory effect of BrcGMP was not additive with ANP, amiloride, or ouabain. Amphotericin, which enhances Na+ entry into cells, prevented the inhibitory effect of 8-BrcGMP. These results indicate that 8-BrcGMP, like ANP, inhibited Na+ entry in IMCD cells. hANP stimulated a 10-fold increase in cGMP in IMCD cells without altering IMCD cAMP levels or OMCD cGMP levels. Isobutyl methylxanthine, which inhibits phosphodiesterase activity, enhanced both cGMP accumulation and inhibition of QO2 by submaximal levels (10(-9) M) of ANP. Nitroprusside raised cGMP levels in both IMCD and OMCD cells but inhibited QO2 only in IMCD cells. We conclude that cGMP mediates the transport effects of ANP in IMCD cells. Our results indicate that cGMP may play an important role in the regulation of sodium transport in renal epithelia.
 ...
PMID:cGMP mediates effects of atrial peptides on medullary collecting duct cells. 243 76

An electrogenic proton-translocating ATPase (H+-ATPase) has been described in turtle urinary bladder and bovine and rat renal medulla. In the present study, a membrane fraction with ATP-dependent H+ transport activity was isolated from human renal medulla. Intravesicular acidification was assessed by acridine orange absorbance changes. Proton transport was abolished by N-ethylmaleimide but not oligomycin or vanadate, differentiating this H+-ATPase from mitochondrial F0-F1 H+-ATPase and gastric H+-K+-ATPase. In addition, vesicular proton uptake was demonstrated to be independent of sodium and potassium cotransport. Proton translocation rate increased when transmembrane potential was clamped with valinomycin supporting an electrogenic mechanism. Hydrogen ion transport was dependent on the presence of chloride or bromide, since substitution by fluoride or nitrate markedly decreased intravesicular acidification. The transport characteristics of this proton-translocating ATPase are similar to those described for turtle urinary bladder and bovine and rat renal medulla, which have been assumed to play a role in urinary acidification by the medullary collecting duct.
 ...
PMID:ATP-dependent proton transport in human renal medulla. 287 44

Adenosine plays several roles in the kidney mediated by the specific receptors A1, A2, and possibly A3. We studied the localization of adenosine A1 receptor mRNA in rat nephron segments using reverse transcription and polymerase chain reaction (RT-PCR). The nephron segments of male Sprague-Dawley rats (6 to 8 weeks old) were microdissected. Total RNA was prepared by the acid-guanidinium-phenol-chloroform method and used in the following RT-PCR assay. Because the PCR primers spanned no intron, samples reacted in the absence of RT were used as controls for amplification of genomic DNA. The PCR products were size-fractionated by electrophoresis, visualized with ethidium bromide staining, and confirmed by Southern blot analysis. PCR products were detected in all of the nephron segments examined. No signals were detected in samples reacted in the absence of RT. Strong signals were detected in glomeruli, medullary collecting duct, cortical thick ascending limb, and medullary thick ascending limb, while weak signals were found in proximal convoluted and straight tubules. Previously, the presence of A1 receptors has been demonstrated in glomeruli, collecting duct, and thick ascending limb in the rat kidney by autoradiography and binding studies. In addition to these segments, we further detected A1 receptor mRNA in proximal convoluted and straight tubules. Thus, A1 receptor mRNA seems to be broadly expressed along the nephron.
 ...
PMID:Adenosine A1 receptor mRNA in microdissected rat nephron segments. 749 92

In the cortical collecting duct (CCD), aldosterone increases the number of functionally active Na-K-adenosin-etriphosphatase (Na-K-ATPase) molecules by a mechanism involving an isoform-specific increase in the abundance of the Na-K-ATPase alpha 1- and beta 1-subunit protein. However, the molecular basis for the response, particularly in the mammalian CCD in vivo, has remained unclear. To resolve this issue, reverse transcription (RT) and a competitive polymerase chain reaction (PCR) were employed to study mineralocorticoid-dependent regulation of alpha 1- and beta 1-subunit mRNA in the rat CCD. Na-K-ATPase subunit-specific oligonucleotides primers were used in the PCR to amplify reverse-transcribed subunit mRNA (RT-mRNA) from single microdissected CCD. Control templates were constructed (84-bp deletion mutation of the rat Na-K-ATPase alpha 1-subunit cDNA and 70-bp deletion of the beta 1-subunit cDNA), serially diluted, and coamplified with the wild-type Na-K-ATPase subunit RT-mRNA from single CCD. PCR products of predicted size were observed by ethidium bromide staining. Southern blots with an internal subunit-specific oligonucleotide confirmed Na-K-ATPase alpha 1- and beta 1-subunit identity. The ratio of the amplified wild-type to mutant PCR products was found to be linear over the range of input control cDNA tested so that the amount of subunit mRNA could be determined. A chronic reduction in corticosteroid levels by bilateral adrenalectomy (7 days) reduced the apparent level of alpha 1-subunit transcript by 54.0 +/- 6.3% but not the beta 1-subunit. Administering aldosterone to physiological levels is sufficient to restore CCD alpha 1-subunit mRNA abundance toward control levels within 6 h. We conclude the following: 1) regulation of Na-K-ATPase of CCD in vivo can be attributed, at least in part, to mineralocorticoid-dependent control of Na-K-ATPase alpha 1-subunit mRNA abundance; and 2) competitive PCR may provide a sensitive and quantitative tool for determining hormone-dependent regulation of mRNA abundance in nephron segments.
 ...
PMID:Aldosterone-dependent regulation of Na-K-ATPase subunit mRNA in the rat CCD: competitive PCR analysis. 876 Feb 37

The chloride conductance of inner medullary collecting duct cells (mIMCD-3 cell line) has been investigated using the whole cell configuration of the patch clamp technique. Seventy-seven percent of cells were chloride selective when measured with a NaCl-rich bathing solution and a TEACl-rich pipette solution. Seventy-five percent of chloride-selective cells (90/144) had whole cell currents which exhibited an outwardly-rectifying (OR) current-voltage (I/V) relationship, while the remaining cells exhibited a linear (L) I/V relationship. The properties of the OR and L chloride currents were distinct. OR currents (mean current densities at +/- 60 mV of 66 +/- 5 pA/pF and 44 +/- 3 pA/pF), were time- and voltage-independent with an anion selectivity (from calculated permeability ratios) of SCN- (2.3), NO3- (1.8), ClO4- (1.7), Br- (1.7), I- (1.6), Cl- (1.0), HCO3- (0.5), gluconate- (0.2). Bath additions of NPPB, flufenamate, glibenclamide (all 100 microM) and DIDS (500 microM) produced varying degrees of block of OR currents with NPPB being the most potent (IC50 of approximately 50 microM) while DIDS was the least effective. Linear chloride currents had similar current densities to the OR chloride currents and were also time- and voltage-independent. The anion selectivity sequence was SCN- (2.5), NO3- (1.9), Br- (1.4), I- (1.1), Cl- (1.0), ClO4- (0.5), HCO3- (0.5), gluconate- (0.3). In contrast to the OR conductance, glibenclamide was the most potent and DIDS the least potent blocker of L currents. An IC50 of > 100 microM was observed for NPPB block. Neither OR of L chloride currents were affected by acutely or chronically increased intracellular cAMP and were not affected when intracellular Ca2+ levels were increased or decreased. The molecular identity and physiological role of OR and linear currents in mIMCD-3 cells are discussed.
 ...
PMID:Characterization of whole cell chloride conductances in a mouse inner medullary collecting duct cell line mIMCD-3. 882 25

Whole cell recordings were performed on rat inner medullary collecting duct (IMCD) cells in primary culture. With 140 mmol/l CsCl in bath and pipette we find within 10 min a 60-fold increase in membrane conductance from 0.02 +/- 0.003 to 1.2 +/- 0.1 nS/pF when bath osmolarity is decreased from 600 to 500 mosmol/l. The effect is due to the activation of an outwardly rectifying anion conductance with the anion selectivity SCN- > I- > NO-3 > Br- > Cl- > F- > isethionate > gluconate > or = aspartate > or = glutamate. A relative permeability of the organic osmolyte taurine to Cl- (Ptaurine: PCl-) of 0.15 was detected. With taurine in pipette and bath, the channel exhibits a nearly identical activation and sensitivity profile to a variety of anion channel blockers as under symmetrical Cl- conditions. Furthermore, the 50% inhibitory concentration value for the effect of 5-nitro-2-(3-phenylpropylamino)benzoate on both currents is virtually identical. We conclude that hypotonic stress increases the anion conductance of rat IMCD cells and that this anion conductance mediates taurine efflux.
 ...
PMID:Taurine permeation through swelling-activated anion conductance in rat IMCD cells in primary culture. 885 11

In the present study we used whole-cell patch clamp recordings to investigate swelling-activated Cl-currents (ICl-swell) in M-1 mouse cortical collecting duct (CCD) cells. Hypotonic cell swelling reversibly increased the whole-cell Cl- conductance by about 30-fold. The I-V relationship was outwardly-rectifying and ICl-swell displayed a characteristic voltage-dependence with relatively fast inactivation upon large depolarizing and slow activation upon hyperpolarizing voltage steps. Reversal potential measurements revealed a selectivity sequence SCN- > I- > Br- > Cl- > > gluconate. ICl-swell was inhibited by tamoxifen, NPPB (5-nitro-2(3-phenylpropylamino)-benzoate), DIDS (4,4'-diisothiocyanostilbene-2,2'-disulphonic acid), flufenamic acid, niflumic acid, and glibenclamide, in descending order of potency. Extracellular cAMP had no significant effect. ICl-swell was Ca2+ independent, but current activation depended on the presence of a high-energy gamma-phosphate group from intracellular ATP or ATP gamma S. Moreover, it depended on the presence of intracellular Mg2+ and was inhibited by staurosporine, which indicates that a phosphorylation step is involved in channel activation. Increasing the cytosolic Ca2+ concentration by using ionomycin stimulated Cl- currents with a voltage dependence different from that of ICl-swell. Analysis of whole-cell current records during early onset of ICl-swell and during final recovery revealed discontinuous step-like changes of the whole-cell current level which were not observed under nonswelling conditions. A single-channel I-V curve constructed using the smallest resolvable current transitions detected at various holding potentials and revealed a slope conductance of 55, 15, and 8 pS at +120, 0, and -120 mV, respectively. The larger current steps observed in these recordings had about 2, 3, or 4 times the size of the putative single-channel current amplitude, suggesting a coordinated gating of several individual channels or channel subunits. In conclusion we have functionally characterized ICl-swell in M-1 CCD cells and have identified the underlying single channels in whole-cell current recordings.
 ...
PMID:Cell swelling activates ATP-dependent voltage-gated chloride channels in M-1 mouse cortical collecting duct cells. 888 62

To investigate halide selectivity patterns of cortical collecting duct (CCD) intercalated cells (ICs), intracellular pH (pHi) was measured in perfused rabbit outer CCD ICs in Na(+)-free, HCO-3-buffered, 115 mM Cl solutions. Apical anion exchange activity was measured as the dpH/dt after lumen Cl- replacement with gluconate. The perfusate was randomly changed to equimolar Br-, F-, or I-. Addition of Br- to the lumen in place of gluconate caused a brisk acidification similar to that with Cl- return. The acidification rate with I- replacement was only approximately 25% of that seen with Cl- readdition, and F- substitution resulted in a small alkalinization. In a separate protocol, each halide was substituted for lumen Cl-. Replacement of lumen Cl- with Br- resulted in intracellular acidification, whereas F- substitution caused an increase in pHi similar to that with gluconate. A slower rate of alkalinization was seen with I-. Separate tubules were perfused and bathed in Cl(-)-free gluconate solutions for 10 min, and then either Cl- or Br- was returned to the lumen. Similar rates of acidification were found with either Cl- or Br- return. Taken together, the results show that, at a halide concentration of 115 mM, the halide selectivity transport pattern of the apical anion exchanger of CCD ICs is Cl- = Br- > I- > F-.
 ...
PMID:Halide transport patterns of apical anion exchange in rabbit cortical collecting duct intercalated cells. 889 9


1 2 Next >>