期刊
AMERICAN JOURNAL OF PHYSIOLOGY-RENAL PHYSIOLOGY
卷 299, 期 3, 页码 F507-F516出版社
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajprenal.00222.2010
关键词
potassium; volume regulation; mechanotransduction; intercalated cells; parallel plate flow chamber; calcein
资金
- University of California-Davis/National Institutes of Health (NIH) NeuroMab Facility
- NIH [U24-NS-050606]
- National Institutes of Diabetes and Digestive and Kidney Diseases [RO1 DK071014, RO1 DK73070]
- American Heart Association-Heartland Affiliate [0610059Z]
- American Recovery and Reinvestment Act [3R01 DK071014-03S1]
- NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES [R01DK071014, R01DK073070] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE [U24NS050606] Funding Source: NIH RePORTER
Holtzclaw JD, Liu L, Grimm PR, Sansom SC. Shear stress-induced volume decrease in C11-MDCK cells by BK-alpha/beta 4. Am J Physiol Renal Physiol 299: F507-F516, 2010. First published June 24, 2010; doi:10.1152/ajprenal.00222.2010.-Large-conductance, calcium-activated potassium channels (BK) are expressed in principal cells (PC) and intercalated cells (IC) in mammalian nephrons as BK-alpha/beta 1 and BK-alpha/beta 4, respectively. IC, which protrude into the lumens of tubules, express substantially more BK than PC despite lacking sufficient Na-K-ATPase to support K secretion. We previously showed in mice that IC exhibit size reduction when experiencing high distal flows induced by a high-K diet. We therefore tested the hypothesis that BK-alpha/beta 4 are regulators of IC volume via a shear stress (tau)-induced, calcium-dependent mechanism, resulting in a reduction in intracellular K content. We determined by Western blot and immunocytochemical analysis that C11-Madin-Darby canine kidney cells contained a predominance of BK-alpha/beta 4. To determine the role of BK-alpha/beta 4 in tau-induced volume reduction, we exposed C11 cells to tau and measured K efflux by flame photometry and cell volume by calcein staining, which changes inversely to cell volume. With 10 dynes/cm(2), calcein intensity significantly increased 39% and monovalent cationic content decreased significantly by 37% compared with static conditions. Furthermore, the shear-induced K loss from C11 was abolished by the reduction of extracellular calcium, addition of 5 mM TEA, or BK-beta 4 small interfering (si) RNA, but not by addition of nontarget siRNA. These results show that BK-alpha/beta 4 plays a role in shear-induced K loss from IC, suggesting that BK-alpha/beta 4 regulate IC volume during high-flow conditions. Furthermore, these results support the use of C11 cells as in vitro models for studying BK-related functions in IC of the kidney.
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