scholarly journals The Epithelial Na+Channel Is Inhibited by a Peptide Derived from Proteolytic Processing of Its α Subunit

2006 ◽  
Vol 281 (27) ◽  
pp. 18901-18907 ◽  
Author(s):  
Marcelo D. Carattino ◽  
Shaohu Sheng ◽  
James B. Bruns ◽  
Joseph M. Pilewski ◽  
Rebecca P. Hughey ◽  
...  
2003 ◽  
Vol 278 (39) ◽  
pp. 37073-37082 ◽  
Author(s):  
Rebecca P. Hughey ◽  
Gunhild M. Mueller ◽  
James B. Bruns ◽  
Carol L. Kinlough ◽  
Paul A. Poland ◽  
...  

2005 ◽  
Vol 280 (28) ◽  
pp. 26206-26215 ◽  
Author(s):  
Ossama B. Kashlan ◽  
Shaohu Sheng ◽  
Thomas R. Kleyman

2006 ◽  
Vol 291 (3) ◽  
pp. F683-F693 ◽  
Author(s):  
Zuhal Ergonul ◽  
Gustavo Frindt ◽  
Lawrence G. Palmer

Antibodies directed against subunits of the epithelial Na channel (ENaC) were used together with electrophysiological measurements in the cortical collecting duct to investigate the processing of the proteins in rat kidney with changes in Na or K intake. When animals were maintained on a low-Na diet for 7–9 days, the abundance of two forms of the α-subunit, with apparent masses of 85 and 30 kDa, increased. Salt restriction also increased the abundance of the β-subunit and produced an endoglycosidase H (Endo H)-resistant pool of this subunit. The abundance of the 90-kDa form of the γ-subunit decreased, whereas that of a 70-kDa form increased and this peptide also exhibited Endo H-resistant glycosylation. These changes in α- and γ-subunits were correlated with increases in Na conductance elicited by a 4-h infusion with aldosterone. Changes in all three subunits were correlated with decreases in Na conductance when Na-deprived animals drank saline for 5 h. We conclude that ENaC subunits are mainly in an immature form in salt-replete rats. With Na depletion, the subunits mature in a process that involves proteolytic cleavage and further glycosylation. Similar changes occurred in α- and γ- but not β-subunits when animals were treated with exogenous aldosterone, and in β- and γ- but not α-subunits when animals were fed a high-K diet. Changes in the processing and maturation of the channels occur rapidly enough to be involved in the daily regulation of ENaC activity and Na reabsorption by the kidney.


1999 ◽  
Vol 438 (5) ◽  
pp. 709-715 ◽  
Author(s):  
S. Gründer ◽  
N. Fowler Jaeger ◽  
I. Gautschi ◽  
L. Schild ◽  
B.C. Rossier

1999 ◽  
Vol 438 (5) ◽  
pp. 709-715 ◽  
Author(s):  
S. Gründer ◽  
N. Fowler Jaeger ◽  
I. Gautschi ◽  
L. Schild ◽  
B.C. Rossier

1999 ◽  
Vol 104 (7) ◽  
pp. 967-974 ◽  
Author(s):  
Olivier Bonny ◽  
Ahmed Chraibi ◽  
Jan Loffing ◽  
Nicole Fowler Jaeger ◽  
Stefan Gründer ◽  
...  

1997 ◽  
Vol 272 (34) ◽  
pp. 21075-21083 ◽  
Author(s):  
Iskander I. Ismailov ◽  
Thomas Kieber-Emmons ◽  
Chaomei Lin ◽  
Bakhram K. Berdiev ◽  
Vadim Gh. Shlyonsky ◽  
...  

2001 ◽  
Vol 280 (2) ◽  
pp. F214-F222 ◽  
Author(s):  
Vincent Couloigner ◽  
Michel Fay ◽  
Sabri Djelidi ◽  
Nicolette Farman ◽  
Brigitte Escoubet ◽  
...  

In the cochlea, endolymph is a K-rich and Na-poor fluid. The purpose of the present study was to check the presence and to assess the role of epithelial Na channel (ENaC) in this organ. α-, β-, and γ-ENaC subunit mRNA, and proteins were detected in rat cochlea by RT-PCR and Western blot. α-ENaC subunit mRNA was localized by in situ hybridization in both epithelial (stria vascularis, spiral prominence, spiral limbus) and nonepithelial structures (spiral ligament, spiral ganglion). The α-ENaC-positive tissues were also positive for β-subunit mRNA (except spiral ganglion) or for γ-subunit mRNA (spiral limbus, spiral ligament, and spiral ganglion), but the signals of β- and γ-subunits were weaker than those observed for α-subunit. In vivo, the endocochlear potential was recorded in guinea pigs under normoxic and hypoxic conditions after endolymphatic perfusion of ENaC inhibitors (amiloride, benzamil) dissolved either in K-rich or Na-rich solutions. ENaC inhibitors altered the endocochlear potential when Na-rich but not when K-rich solutions were perfused. In conclusion, ENaC subunits are expressed in epithelial and nonepithelial cochlear structures. One of its functions is probably to maintain the low concentration of Na in endolymph.


1999 ◽  
Vol 274 (14) ◽  
pp. 9648-9655 ◽  
Author(s):  
Thomas Kieber-Emmons ◽  
Chaomei Lin ◽  
Mary H. Foster ◽  
Thomas R. Kleyman

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