Epithelial sodium channels (ENaCs) play a vital role in regulating sodium entry into polarized epithelia, including the kidney. Maintenance of whole body sodium and water balance depends on continuous regulation of ENaC activity by hormones. There is reason to suspect that studies of ENaC regulation may be compromised by several types of artifacts, of which three varieties will be examined in this project. (A) Protocol dependence in the formation of patches may influence the response to hormones. (B) The effects of hormones may depend on baseline ENaC density in the membrane. (C) The effects of hormones may differ in short- or open-circuited tissues. This project will generally examine ENaC function in A6 cells as a model tissue on a more fundamental level than is usually done. The results will help to establish the validity of much published data in the literature, and will guide future studies by providing information on the intrinsic limitations of different techniques used to study ENaCs.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
2R01DK030824-13A1
Application #
2744545
Study Section
Special Emphasis Panel (ZRG4-GMB (01))
Program Officer
Scherbenske, M James
Project Start
1982-04-01
Project End
2002-11-30
Budget Start
1998-12-01
Budget End
1999-11-30
Support Year
13
Fiscal Year
1999
Total Cost
Indirect Cost
Name
University of Illinois Urbana-Champaign
Department
Physiology
Type
Schools of Arts and Sciences
DUNS #
041544081
City
Champaign
State
IL
Country
United States
Zip Code
61820
Paunescu, T G; Helman, S I (2001) cAmp activation of apical membrane Cl(-) channels: theoretical considerations for impedance analysis. Biophys J 81:838-51
Paunescu, T G; Helman, S I (2001) PGE(2) activation of apical membrane Cl(-) channels in A6 epithelia: impedance analysis. Biophys J 81:852-66
Butterworth, M B; Helman, S I; Els, W J (2001) cAMP-sensitive endocytic trafficking in A6 epithelia. Am J Physiol Cell Physiol 280:C752-62
Paunescu, T G; Blazer-Yost, B L; Vlahos, C J et al. (2000) LY-294002-inhibitable PI 3-kinase and regulation of baseline rates of Na(+) transport in A6 epithelia. Am J Physiol Cell Physiol 279:C236-47
Awayda, M S; Van Driessche, W; Helman, S I (1999) Frequency-dependent capacitance of the apical membrane of frog skin: dielectric relaxation processes. Biophys J 76:219-32
Helman, S I; Liu, X; Baldwin, K et al. (1998) Time-dependent stimulation by aldosterone of blocker-sensitive ENaCs in A6 epithelia. Am J Physiol 274:C947-57
Blazer-Yost, B L; Liu, X; Helman, S I (1998) Hormonal regulation of ENaCs: insulin and aldosterone. Am J Physiol 274:C1373-9
Els, W J; Liu, X; Helman, S I (1998) Differential effects of phorbol ester (PMA) on blocker-sensitive ENaCs of frog skin and A6 epithelia. Am J Physiol 275:C120-9
Helman, S I; Liu, X (1997) Substrate-dependent expression of Na+ transport and shunt conductance in A6 epithelia. Am J Physiol 273:C434-41
Blazer-Yost, B L; Helman, S I (1997) The amiloride-sensitive epithelial Na+ channel: binding sites and channel densities. Am J Physiol 272:C761-9

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