HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 292/4/F1190    most recent 00399.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Frindt, G. Articles by Palmer, L. G. Search for Related Content PubMed PubMed Citation Articles by Frindt, G. Articles by Palmer, L. G.

Na channel expression and activity in the medullary collecting duct of rat kidney

Department of Physiology and Biophysics, Weill Medical College of Cornell University, New York, New York

Submitted 9 October 2006 ; accepted in final form 22 December 2006

The expression and activity of epithelial Na⁺ channels (ENaC) in the medullary collecting duct of the rat kidney were examined using a combination of whole cell patch-clamp measurements of amiloride-sensitive currents (I_Na) in split-open tubules and Western blot analysis of -, -, and -ENaC proteins. In the outer medullary collecting duct, amiloride-sensitive currents were undetectable in principal cells from control animals but were robust when rats were treated with aldosterone (I_Na = 960 ± 160 pA/cell) or fed a low-Na diet (I_Na = 440 ± 120 pA/cell). In both cases, the currents were similar to those measured in principal cells of the cortical collecting duct from the same animals. In the inner medullary collecting duct, currents were much lower, averaging 120 ± 20 pA/cell in aldosterone-treated rats. Immunoblots showed that all three ENaC subunits were expressed in the cortex, outer medulla, and inner medulla of the rat kidney. When rats were fed a low-Na diet for 1 wk, similar changes in - and -ENaC occurred in all three regions of the kidney; the amounts of full-length as well as putative cleaved -ENaC protein increased, and the fraction of -ENaC protein in the cleaved state increased at the expense of the full-length protein. The appearance of a presumably fully glycosylated form of -ENaC in Na-depleted animals was observed mainly in the outer and inner medulla. These findings suggest that the capability of hormone-regulated, channel-mediated Na reabsorption by the nephron extends at least into the outer medullary collecting duct.

ENaC; aldosterone; outer medulla; inner medulla

This article has been cited by other articles:

				A. M. Weinstein A mathematical model of distal nephron acidification: diuretic effects Am J Physiol Renal Physiol, November 1, 2008; 295(5): F1353 - F1364. [Abstract] [Full Text] [PDF]

				G. Fejes-Toth, G. Frindt, A. Naray-Fejes-Toth, and L. G. Palmer Epithelial Na+ channel activation and processing in mice lacking SGK1 Am J Physiol Renal Physiol, June 1, 2008; 294(6): F1298 - F1305. [Abstract] [Full Text] [PDF]

				W. G. Hill, M. B. Butterworth, H. Wang, R. S. Edinger, J. Lebowitz, K. W. Peters, R. A. Frizzell, and J. P. Johnson The Epithelial Sodium Channel (ENaC) Traffics to Apical Membrane in Lipid Rafts in Mouse Cortical Collecting Duct Cells J. Biol. Chem., December 28, 2007; 282(52): 37402 - 37411. [Abstract] [Full Text] [PDF]