Effects of purinergic stimulation, CFTR and osmotic stress on amiloride-sensitive Na+ transport in epithelia and Xenopus oocytes

Schreiber, R., Konig, J., Sun, J., Markovich, D. and Kunzelmann, K. (2003) Effects of purinergic stimulation, CFTR and osmotic stress on amiloride-sensitive Na+ transport in epithelia and Xenopus oocytes. Journal of Membrane Biology, 192 2: 101-110. doi:10.1007/s00232-002-1067-8


Author Schreiber, R.
Konig, J.
Sun, J.
Markovich, D.
Kunzelmann, K.
Title Effects of purinergic stimulation, CFTR and osmotic stress on amiloride-sensitive Na+ transport in epithelia and Xenopus oocytes
Journal name Journal of Membrane Biology   Check publisher's open access policy
ISSN 0022-2631
1432-1424
Publication date 2003-01-01
Sub-type Article (original research)
DOI 10.1007/s00232-002-1067-8
Volume 192
Issue 2
Start page 101
End page 110
Total pages 10
Editor W.R. Loewenstein
Place of publication New York
Publisher Springer-verlag
Language eng
Subject C1
270699 Physiology not elsewhere classified
730118 Organs, diseases and abnormal conditions not elsewhere classified
Abstract Both stimulation of purinergic receptors by ATP and activation of the cystic fibrosis transmembrane conductance regulator (CFTR) inhibit amiloride-sensitive Na+ transport and activate Cl-secretion. These changes in ion transport may well affect cell volume. We therefore examined whether cell shrinkage or cell swelling do affect amiloride-sensitive Na+ transport in epithelial tissues or Xenopus oocytes and whether osmotic stress interferes with regulation of Na+ transport by ATP or CFTR. Stimulation of purinergic receptors by ATP/UTP or activation of CFTR by IBMX and forskolin inhibited amiloride-sensitive transport in mouse trachea and colon, respectively, by a mechanism that was Cl- dependent. When exposed to a hypertonic but not hypotonic bath solution, amiloride-sensitive Na+ transport was inhibited in mouse trachea and colon, independent of the extracellular Cl- concentration. Both inhibition of Na+ transport by hypertonic bath solution and ATP were additive. When coexpressed in Xenopus oocytes, activation of CFTR by IBMX and forskolin inhibited the epithelial Na+ channel (ENaC) in a Cl(-)dependent fashion. However, both hypertonic and hypotonic bath solutions showed only minor effects on amiloride-sensitive conductance, independent of the bath Cl- concentration. Moreover, CFTR-induced inhibition of ENaC could be detected in chocytes even after exposure to hypertonic or bypotonic bath solutions. We conclude that amiloride-sensitive Na+ absorption in mouse airways and colon is inhibited by cell shrinkage by a mechanism that does not interfere with purinergic and CFTR-mediated inhibition of ENaC.
Keyword Biochemistry & Molecular Biology
Cell Biology
Physiology
CFTR
Enac
Xenopus Oocytes
Mouse Trachea
Cystic Fibrosis
Cell Swelling
Osmotic Stress
UTP
ATP
Purinergic Receptors
Epithelial Transport
Transmembrane Conductance Regulator
Cystic-fibrosis Airways
Hypertonic Saline
Ion-transport
Extracellular Nucleotides
Mediated Inhibition
Cytosolic Na+
Duct Cells
Wild-type
Absorption
Q-Index Code C1

 
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Created: Wed, 15 Aug 2007, 12:27:26 EST