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  Amiloride-inhibitable Na+ conductance in rat proximal tubule

Willman, J., Bleich, M., Rizzo, M., Schmidt-Hieber, M., Ullrich, K. J., & Greger, R. (1997). Amiloride-inhibitable Na+ conductance in rat proximal tubule. Pflügers Archiv: European Journal of Physiology, 434(2), 173-178. doi:10.1007/s004240050380.

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 Creators:
Willman, J.K.1, Author
Bleich, M.1, Author
Rizzo, M.1, Author
Schmidt-Hieber, M.1, Author
Ullrich, Karl Julius2, Author              
Greger, Rainer1, Author
Affiliations:
1Physiologisches Institut der Albert-Ludwigs-Universitat, Hermann-Herder-Strasse 7, D-79104 Freiburg i. Br., Germany, ou_persistent22              
2Emeritusgroup Physiology, Max Planck Institute of Biophysics, Max Planck Society, ou_3273468              

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Free keywords: Na+ channel; Epithelial Na+ channel; Na+ absorption; Na+ deprivation; Patch-clamp technique
 Abstract: Previous single-channel recordings from the luminal membrane of the rabbit proximal tubule have revealed amiloride-inhibitable Na+ channels of a characteristic conductance range. The present study aimed to pursue this issue in rat proximal tubule. Control rats were compared to those put on a low-Na+ diet or pretreated by triamcinolone injections (s.c.). Stimulation of Na+ absorption by glucocorticoids was verified by examining the transepithelial voltage in Ussing chamber studies of the distal colon. The membrane voltage (Vm) of isolated, in-vitro-perfused proximal tubule segments was measured in patch-clamp and impalement studies. It was found that amiloride hyperpolarized Vm significantly by 2.1 ± 0.9 mV (n = 26) in tubules of control rats, by 3.9 ± 0.7 mV (n = 12) in rats put on a low-Na+ diet and by 3.7 ± 1.0 mV (n = 17) in rats treated with glucocorticoids. The effect of amiloride was concentration dependent with a half-maximal effect at < 1 micromol/l. RT-PCR techniques were used to search for the presence of the alpha-, beta- and gamma-subunits of the epithelial Na+ channel in isolated proximal tubule segments. The presence of the respective mRNAs was verified. These data indicate that: (1) amiloride-inhibitable Na+ channels are present in rate proximal tubules; (2) the Na+ conductance may be up-regulated by Na+ deprivation but is still very limited when compared to total cell conductance; (3) therefore, the contribution of Na+-channel-mediated absorption to total proximal Na+ absorption is probably small.

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Language(s): eng - English
 Dates: 1997-01-221996-08-051997-01-281997-05-01
 Publication Status: Published in print
 Pages: 6
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1007/s004240050380
PMID: 9136671
 Degree: -

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Title: Pflügers Archiv: European Journal of Physiology
  Other : Pflügers Arch. Europ. J. Physiol.
Source Genre: Journal
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Publ. Info: Heidelberg : Springer-Verlag
Pages: - Volume / Issue: 434 (2) Sequence Number: - Start / End Page: 173 - 178 Identifier: ISSN: 0031-6768
CoNE: https://pure.mpg.de/cone/journals/resource/954925432380