Abstract |
Autosomal recessive polycystic kidney disease ( ARPKD) is characterized by the progressive dilatation of collecting ducts, the nephron segments responsible for the final renal regulation of sodium, potassium, acid-base, and water balance. Murine models of ARPKD possess mutations in genes encoding cilia-associated proteins, including Tg737 in orpk mice. New findings implicate defects in structure/function of primary cilia as central to the development of polycystic kidney disease. Our group (Liu W, Xu S, Woda C, Kim P, Weinbaum S, and Satlin LM, Am J Physiol Renal Physiol 285: F998-F1012, 2003) recently reported that increases in luminal flow rate in rabbit collecting ducts increase intracellular Ca(2+) concentration ([Ca(2+)](i)) in cells therein. We thus hypothesized that fluid shear acting on the apical membrane or hydrodynamic bending moments acting on the cilium increase renal epithelial [Ca(2+)](i). To further explore this, we tested whether flow-induced [Ca(2+)](i) transients in collecting ducts from mutant orpk mice, which possess structurally abnormal cilia, differ from those in controls. Isolated segments from 1- and 2-wk-old mice were microperfused in vitro and loaded with fura 2; [Ca(2+)](i) was measured by digital ratio fluorometry before and after the rate of luminal flow was increased. All collecting ducts responded to an increase in flow with an increase in [Ca(2+)](i), a response that appeared to be dependent on luminal Ca(2+) entry. However, the magnitude of the increase in [Ca(2+)](i) in 2- but not 1-wk-old mutant orpk animals was blunted. We speculate that this defect in mechano-induced Ca(2+) signaling in orpk mice leads to aberrant structure and function of the collecting duct in ARPKD.
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Authors | Wen Liu, Noel S Murcia, Yi Duan, Sheldon Weinbaum, Bradley K Yoder, Erik Schwiebert, Lisa M Satlin |
Journal | American journal of physiology. Renal physiology
(Am J Physiol Renal Physiol)
Vol. 289
Issue 5
Pg. F978-88
(Nov 2005)
ISSN: 1931-857X [Print] United States |
PMID | 15972389
(Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
- Fluorescent Dyes
- Tg737Rpw protein, mouse
- Tumor Suppressor Proteins
- Calcium
- Fura-2
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Topics |
- Animals
- Calcium
(pharmacokinetics)
- Cilia
(pathology)
- Dilatation, Pathologic
- Fluorescent Dyes
- Fluorometry
- Fura-2
- Kidney Tubules, Collecting
(physiology)
- Mice
- Mutation
- Polycystic Kidney, Autosomal Recessive
(physiopathology)
- Tumor Suppressor Proteins
(genetics, physiology)
- Urodynamics
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