scholarly journals Na restriction activates epithelial Na channels in rat kidney through two mechanisms and decreases distal Na+ delivery

2018 ◽  
Vol 596 (16) ◽  
pp. 3585-3602 ◽  
Author(s):  
Gustavo Frindt ◽  
Lei Yang ◽  
Krister Bamberg ◽  
Lawrence G. Palmer
Keyword(s):  
Rat Kidney ◽  
Na Channels ◽  
Epithelial Na Channels

Na channels in the rat connecting tubule

2004 ◽  
Vol 286 (4) ◽  
pp. F669-F674 ◽  
Author(s):  
Gustavo Frindt ◽  
Lawrence G. Palmer
Keyword(s):  
Rat Kidney ◽  
Relative Magnitude ◽  
Na Channels ◽  
Connecting Tubule ◽  
Epithelial Na Channels ◽  
Collecting Tubule ◽  
Inward Currents ◽  
Opening And Closing ◽  
Aggregate Population ◽  
In Cells

Epithelial Na channels were investigated using patch-clamp techniques in connecting tubule (CNT) segments isolated from rat kidney. Cell-attached patches with Li+ in the patch pipette contained channels with conductances for inward currents of 13–16 pS and slow opening and closing kinetics, similar to properties of Na channels in the cortical collecting tubule (CCT). Macroscopic amiloride-sensitive currents ( INa) were also observed under whole cell clamp conditions. These currents were undetectable in cells from control rats but were large when the animals were infused with aldosterone (1,380 ± 340 pA/cell at a holding potential of -100 mV) or fed a high-K diet (670 ± 260 pA/cell) for 1 wk. Under both of these conditions, currents in cells of the CNT were two- to fourfold larger than currents in cells of the CCT of the same animals. In aldosterone-treated animals, currents in cells of the initial collecting tubule (iCT) were intermediate, such that the relative magnitude of INa was as follows: CNT > iCT > CCT. Quantitative analysis of the results suggests that the maximal capacity of the aggregate population of CNTs to reabsorb Na could be as high as 18 μmol/min, or ∼10% of the filtered load of Na. This capacity is ∼10 times higher than that of the CCT.

Epithelial Na Channels: Function and Diversity

1992 ◽  
Vol 54 (1) ◽  
pp. 51-66 ◽  
Author(s):  
L G Palmer
Keyword(s):  
Na Channels ◽  
Epithelial Na Channels

scholarly journals Acute effects of aldosterone on the epithelial Na channel in rat kidney

2015 ◽  
Vol 308 (6) ◽  
pp. F572-F578 ◽  
Author(s):  
Gustavo Frindt ◽  
Lawrence G. Palmer
Keyword(s):  
Rat Kidney ◽  
Surface Protein ◽  
Early Response ◽  
Surface Expression ◽  
Na Channel ◽  
Channel Activity ◽  
Acute Effects ◽  
Chronic Stimulation ◽  
Epithelial Na Channels ◽  
Epithelial Na Channel

The acute effects of aldosterone administration on epithelial Na channels (ENaC) in rat kidney were examined using electrophysiology and immunodetection. Animals received a single injection of aldosterone (20 μg/kg body wt), which reduced Na excretion over the next 3 h. Channel activity was assessed in principal cells of cortical collecting ducts as amiloride-sensitive whole cell clamp current ( INa). INa averaged 100 pA/cell, 20–30% of that reported for the same preparation under conditions of chronic stimulation. INa was negligible in control animals that did not receive hormone. The acute physiological response correlated with changes in ENaC processing and trafficking. These effects included increases in the cleaved forms of α-ENaC and γ-ENaC, assessed by Western blot, and increases in the surface expression of β-ENaC and γ-ENaC measured after surface protein biotinylation. These changes were qualitatively and quantitatively similar to those of chronic stimulation. This suggests that altered trafficking to or from the apical membrane is an early response to the hormone and that later increases in channel activity require stimulation of channels residing at the surface.

Mechanisms and sequelae of increased alveolar fluid clearance in hyperoxic rats

1997 ◽  
Vol 272 (3) ◽  
pp. L407-L412 ◽  
Author(s):  
G. Yue ◽  
S. Matalon
Keyword(s):  
Alveolar Epithelial Cells ◽  
Na Channels ◽  
Alveolar Fluid Clearance ◽  
Na Transport ◽  
Alveolar Epithelial ◽  
Lung Fluid ◽  
Isotonic Fluid ◽  
Epithelial Na Channels ◽  
Alveolar Edema

We instilled 4 ml isotonic fluid containing trace amounts of fluorescently labeled dextran (molecular mass 150 kDa) in the lungs of rats exposed to either 85% O(2) for 7 days or to 85% O(2) for 7 days and 100% O(2) for 3 days. We withdrew the fluid every hour for a 3-h period and calculated alveolar fluid clearance (AFC) from changes in dextran concentration. Postinstillation (3 h), AFC values in the control and the two hyperoxic groups were 51 +/- 1, 63 +/- 2, and 62 +/- 3 (SE), respectively (%instilled volume; n > or = 5; P < 0.05). Addition of either 1 mM amiloride or N-ethyl-N-isopropyl amiloride (EIPA) in the instillate decreased the AFC values in all groups 3 h later to approximately 30% of instilled volume. Instillation of phenamil, an irreversible blocker of epithelial Na+ channels into the lungs of rats exposed to 85% O(2) for 7 days and 100% O(2) for 2 days, resulted in a significant increase of their extravascular lung fluid volumes 24 h later. These results demonstrate the existence of EIPA-inhibitable Na+ channels in alveolar epithelial cells in vivo and indicate that an increase in Na+ transport plays an important role in limiting the amount of alveolar edema in O(2)-damaged lungs.

scholarly journals Side Chain Orientation of Residues Lining the Selectivity Filter of Epithelial Na+Channels

2004 ◽  
Vol 280 (9) ◽  
pp. 8513-8522 ◽  
Author(s):  
Shaohu Sheng ◽  
Clint J. Perry ◽  
Ossama B. Kashlan ◽  
Thomas R. Kleyman
Keyword(s):  
Selectivity Filter ◽  
Side Chain ◽  
Na Channels ◽  
Chain Orientation ◽  
Epithelial Na Channels ◽  
Side Chain Orientation

Blockade of epithelial Na+ channels by triamterenes — Underlying mechanisms and molecular basis

1996 ◽  
Vol 432 (5) ◽  
pp. 760-766 ◽  
Author(s):  
A. E. Busch ◽  
H. Suessbrich ◽  
K. Kunzelmann ◽  
A. Hipper ◽  
R. Greger ◽  
...  
Keyword(s):  
Molecular Basis ◽  
Na Channels ◽  
Epithelial Na Channels ◽  
Underlying Mechanisms

scholarly journals Roles of the C Termini of α-, β-, and γ-Subunits of Epithelial Na+Channels (ENaC) in Regulating ENaC and Mediating Its Inhibition by Cytosolic Na+

2001 ◽  
Vol 276 (17) ◽  
pp. 13744-13749 ◽  
Author(s):  
Anuwat Dinudom ◽  
Kieran F. Harvey ◽  
Permsak Komwatana ◽  
Corina N. Jolliffe ◽  
John A. Young ◽  
...  
Keyword(s):  
Na Channels ◽  
Epithelial Na Channels

Epithelial Na Channels and Their Kin

Physiology ◽  
1995 ◽  
Vol 10 (2) ◽  
pp. 61-67 ◽  
Author(s):  
LG Palmer
Keyword(s):  
Na Channels ◽  
Epithelial Na Channels ◽  
Mechanical Sensing ◽  
Stretch Activated Channels

Epithelial Na channels help maintain Na homeostasis by controlling the rate of Na absorption by the kidney and other organs. Surprisingly, they show homology with genes involved in mechanical sensing and transduction. This suggests that epithelial Na channels and stretch-activated channels may be in the same family.

Synthesis and characterization of methylbromoamiloride, a potential biochemical probe of epithelial Na+ channels

1985 ◽  
Vol 86 (1) ◽  
pp. 69-77 ◽  
Author(s):  
Kathy Lazorick ◽  
Christopher Miller ◽  
Sarah Sariban-Sohraby ◽  
Dale Benos
Keyword(s):  
Synthesis And Characterization ◽  
Na Channels ◽  
Epithelial Na Channels
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