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http://hdl.handle.net/1942/1567
Title: | Membrane cholesterol extraction decreases Na+ transport in A6 renal epithelia | Authors: | BALUT, Corina STEELS, Paul RADU, Mihai AMELOOT, Marcel VAN DRIESSCHE, Willy JANS, Danny |
Issue Date: | 2006 | Source: | AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY, 290(1). p. C87-C94 | Abstract: | In this study, we have investigaed the dependence of Na+ transport regulation on membrane cholesterol content in A6 renal epithelia. We continuously monitored short-circuit current (I-SC), transepithelial conductance (G(T)), and transepithelial capacitance (CT) to evaluate the effects of cholesterol extraction from the apical and basolateral membranes in steady-state conditions and during activation with hyposmotic shock, oxytocin, and adenosine. Cholesterol extraction was achieved by perfusing the epithelia with methyl-beta-cyclodextrin (m beta CD) for 1 h. In steady-state conditions, apical membrane cholesterol extraction did not significantly affect the electrophysiological parameters; in contrast, marked reductions were observed during basolateral m beta CD treatment. However, apical m beta CD application hampered the responses of I-SC and G(T) to hypotonicity, oxytocin, and adenosine. Analysis of the blocker-induced fluctuation in I-SC demonstrated that apical m beta CD treatment decreased the epithelial Na+ channel (ENaC) open probability (P-O) in the steady state as well as after activation of Na+ transport by adenosine, whereas the density of conducting channels was not significantly changed as confirmed by CT measurements. Na+ transport activation by hypotonicity was abolished during basolateral m beta CD treatment as a result of reduced Na+/K+ pump activity. On the basis of the findings in this study, we conclude that basolateral membrane cholesterol extraction reduces Na+/K+ pump activity, whereas the reduced cholesterol content of the apical membranes affects the activation of Na+ transport by reducing ENaC P-O. | Keywords: | epithelial Na+ channel; Na+-K+-ATPase activity; short-circuit current; methyl-beta-cyclodextrin; channel open probability; LIPID RAFTS; TRANSEPITHELIAL CAPACITANCE; HUMAN-ERYTHROCYTES; CELLS; CYCLODEXTRINS; STIMULATION; CHANNEL; ORDER; ENAC; PUMP | Document URI: | http://hdl.handle.net/1942/1567 | ISSN: | 0363-6143 | e-ISSN: | 1522-1563 | DOI: | 10.1152/ajpcell.00184.2005 | ISI #: | 000233809600011 | Category: | A1 | Type: | Journal Contribution | Validations: | ecoom 2006 |
Appears in Collections: | Research publications |
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File | Description | Size | Format | |
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MS_Balut - Steels & Jans.pdf | Peer-reviewed author version | 1.06 MB | Adobe PDF | View/Open |
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