|
|
||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-ENaC regulation by aldosterone in CCD
1The Water and Salt Research Center and 2Institute of Anatomy, University of Aarhus, Aarhus, Denmark; 3Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Taegu, Korea; 4Institute of Clinical Medicine, University of Aarhus, Aarhus, Denmark; and 5Laboratory of Kidney and Electrolyte Metabolism, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
Submitted 8 August 2005 ; accepted in final form 26 November 2005
Lithium-induced nephrogenic diabetes insipidus (Li-NDI) is associated with increased urinary sodium excretion and decreased responsiveness to aldosterone and vasopressin. Dysregulation of the epithelial sodium channel (ENaC) is thought to play an important role in renal sodium wasting. The effect of 7-day aldosterone and spironolactone treatment on regulation of ENaC in rat kidney cortex was investigated in rats with 3 wk of Li-NDI. Aldosterone treatment of rats with Li-NDI decreased fractional excretion of sodium (0.83 ± 0.02), whereas spironolactone did not change fractional excretion of sodium (1.10 ± 0.11) compared with rats treated with lithium alone (1.11 ± 0.05). Plasma lithium concentration was decreased by aldosterone (0.31 ± 0.03 mmol/l) but unchanged with spironolactone (0.84 ± 0.18 mmol/l) compared with rats treated with lithium alone (0.54 ± 0.04 mmol/l). Immunoblotting showed increased protein expression of
-ENaC, the 70-kDa form of
-ENaC, and the Na-Cl cotransporter (NCC) in kidney cortex in aldosterone-treated rats, whereas spironolactone decreased
-ENaC and NCC compared with control rats treated with lithium alone. Immunohistochemistry confirmed increased expression of
-ENaC in the late distal convoluted tubule and connecting tubule and also revealed increased apical targeting of all three ENaC subunits (
,
, and
) in aldosterone-treated rats compared with rats treated with lithium alone. Aldosterone did not, however, affect
-ENaC expression in the cortical collecting duct (CCD), which showed weak and dispersed labeling similar to that in rats treated with lithium alone. Spironolactone did not affect ENaC targeting compared with rats treated with lithium alone. This study shows a segment specific lack of aldosterone-mediated
-ENaC regulation in the CCD affecting both
-ENaC protein expression and trafficking, which may explain the increased sodium wasting associated with chronic lithium treatment.
epithelial sodium channel; cortical collecting duct; hypertension; nephrogenic diabetes insipidus
This article has been cited by other articles:
![]() |
H. O'Neill, J. Lebeck, P. B. Collins, T.-H. Kwon, J. Frokiaer, and S. Nielsen Aldosterone-mediated apical targeting of ENaC subunits is blunted in rats with streptozotocin-induced diabetes mellitus Nephrol. Dial. Transplant., May 1, 2008; 23(5): 1546 - 1555. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. J. Bedford, J. P. Leader, R. Jing, L. J. Walker, J. D. Klein, J. M. Sands, and R. J. Walker Amiloride restores renal medullary osmolytes in lithium-induced nephrogenic diabetes insipidus Am J Physiol Renal Physiol, April 1, 2008; 294(4): F812 - F820. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. P. Hughey and T. R. Kleyman Functional cross talk between ENaC and pendrin Am J Physiol Renal Physiol, November 1, 2007; 293(5): F1439 - F1440. [Full Text] [PDF] |
||||
![]() |
J. H. Robben, N. V. A. M. Knoers, and P. M. T. Deen Cell biological aspects of the vasopressin type-2 receptor and aquaporin 2 water channel in nephrogenic diabetes insipidus. Am J Physiol Renal Physiol, August 1, 2006; 291(2): F257 - F270. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |