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: 295/3/F780    most recent 00002.2008v1 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 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 Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Estilo, G. Articles by Satlin, L. M. Search for Related Content PubMed PubMed Citation Articles by Estilo, G. Articles by Satlin, L. M.

Effect of aldosterone on BK channel expression in mammalian cortical collecting duct

¹Medicine/Nephrology and ²Pediatrics/Nephrology, Mount Sinai School of Medicine, New York, New York; and ³Medicine/Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, Pennsylvania

Submitted 3 January 2008 ; accepted in final form 19 June 2008

Apical large-conductance Ca²⁺-activated K⁺ (BK) channels in the cortical collecting duct (CCD) mediate flow-stimulated K⁺ secretion. Dietary K⁺ loading for 10–14 days leads to an increase in BK channel mRNA abundance, enhanced flow-stimulated K⁺ secretion in microperfused CCDs, and a redistribution of immunodetectable channels from an intracellular pool to the apical membrane (Najjar F, Zhou H, Morimoto T, Bruns JB, Li HS, Liu W, Kleyman TR, Satlin LM. Am J Physiol Renal Physiol 289: F922–F932, 2005). To test whether this adaptation was mediated by a K⁺-induced increase in aldosterone, New Zealand White rabbits were fed a low-Na⁺ (LS) or high-Na⁺ (HS) diet for 7–10 days to alter circulating levels of aldosterone but not serum K⁺ concentration. Single CCDs were isolated for quantitation of BK channel subunit (total, -splice variants, β-isoforms) mRNA abundance by real-time PCR and measurement of net transepithelial Na⁺ (J_Na) and K⁺ (J_K) transport by microperfusion; kidneys were processed for immunolocalization of BK -subunit by immunofluorescence microscopy. At the time of death, LS rabbits excreted no urinary Na⁺ and had higher circulating levels of aldosterone than HS animals. The relative abundance of BK -, β₂-, and β₄-subunit mRNA and localization of immunodetectable -subunit were similar in CCDs from LS and HS animals. In response to an increase in tubular flow rate from 1 to 5 nl·min^–1·mm^–1, the increase in J_Na was greater in LS vs. HS rabbits, yet the flow-stimulated increase in J_K was similar in both groups. These data suggest that aldosterone does not contribute to the regulation of BK channel expression/activity in response to dietary K⁺ loading.

ROMK; epithelial sodium channel; mechanoregulation; laminar shear stress; epithelial cell

This article has been cited by other articles:

				W. Liu, Y. Wei, P. Sun, W.-H. Wang, T. R. Kleyman, and L. M. Satlin Mechanoregulation of BK channel activity in the mammalian cortical collecting duct: role of protein kinases A and C Am J Physiol Renal Physiol, October 1, 2009; 297(4): F904 - F915. [Abstract] [Full Text] [PDF]

				P. R. Grimm, D. L. Irsik, L. Liu, J. D. Holtzclaw, and S. C. Sansom Role of BK{beta}1 in Na+ reabsorption by cortical collecting ducts of Na+-deprived mice Am J Physiol Renal Physiol, August 1, 2009; 297(2): F420 - F428. [Abstract] [Full Text] [PDF]

				P. R. Grimm, D. L. Irsik, D. C. Settles, J. D. Holtzclaw, and Steven. C. Sansom Hypertension of Kcnmb1-/- is linked to deficient K secretion and aldosteronism PNAS, July 14, 2009; 106(28): 11800 - 11805. [Abstract] [Full Text] [PDF]