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Upregulation of calbindin D28k in the late distal tubules in the potassium-loaded adrenalectomized mouse kidney.
MedLine Citation:
PMID:  21347582     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
BACKGROUND: The calcium (Ca)-activated potassium (K) channel is an alternative K-secretory pathway in the apical membranes of the distal nephrons of adrenalectomized (ADX) animals. As a potential approach for estimating intracellular Ca(2+) increase, we investigated normal and ADX mice to determine whether dietary K intake would stimulate the expression of the calbindin D28k protein, a cytosolic Ca(2+)-binding protein, along the distal nephron consisting of the early and late portions of the distal convoluted tubule (DCT1 and DCT2, respectively), the CNT, and CCD. METHODS: ADX mice received a control diet plus either 0.3% NaCl solution (C) or a 0.3% NaCl plus 3% KCl solution (HK) for 7 days before the experiment. RESULTS: The mean plasma K concentration and pH were significantly (P < 0.001) higher (7.9 ± 0.3 mEq/l) and lower (7.28 ± 0.02) in the K-loaded ADX mice than in the control ADX mice. The mean urinary K excretion (mEq/day) and urine flow (ml/day) increased significantly (P < 0.0001) from 0.47 ± 0.07 (C) to 4.80 ± 0.57 (HK) and from 1.1 ± 0.2 (C) to 8.8 ± 1.0 (HK). Urinary Ca excretion significantly (P < 0.005 and P < 0.05, respectively) increased in K-loaded normal and ADX mice compared with control normal and ADX mice. Immunofluorescence studies revealed that the relative staining of calbindin was 167.0 ± 15.4%, 291.3 ± 13.8%, and 206.3 ± 11.3% for DCT1, DCT2/CNT, and CCD of normal control mice, respectively. These values increased significantly (P < 0.0001) only in DCT2/CNT (574.8 ± 42%) of the K-loaded ADX mice. CONCLUSION: Upregulation of calbindin in the late distal tubule suggests that Ca(2+)-dependent K transport may function as an alternative mechanism for urinary K excretion in ADX mice.
Authors:
Mizuka Kobayashi; Yukiko Yasuoka; Yuichi Sato; Ming Zhou; Hiroshi Abe; Katsumasa Kawahara; Hirotsugu Okamoto
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-2-24
Journal Detail:
Title:  Clinical and experimental nephrology     Volume:  -     ISSN:  1437-7799     ISO Abbreviation:  -     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-2-24     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9709923     Medline TA:  Clin Exp Nephrol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Department of Anesthesiology, Kitasato University Graduate School of Medical Sciences, 1-15-1 Kitasato, Minami-ku, Sagamihara, 252-0374, Japan.
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