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Whole cell Cl- conductances in mouse choroid plexus epithelial cells do not require CFTR expression
J D Kibble1, C Garner, W H Colledge
1Cell Physiology Group, School of Biological Sciences, University of Manchester, United Kingdom.
The American Journal of Physiology
|June 1, 1997
Summary
Cystic fibrosis transmembrane conductance regulator (CFTR) does not influence anion currents in mouse choroid plexus epithelial cells. Studies found no significant differences in currents between wild-type and CF cells, indicating CFTR is not required for these functions.
Area of Science:
- Physiology
- Ion transport
- Epithelial biology
Background:
- Choroid plexus epithelial cells play a crucial role in cerebrospinal fluid production and regulation.
- Cystic fibrosis transmembrane conductance regulator (CFTR) is a key ion channel implicated in various epithelial functions.
- The role of CFTR in choroid plexus epithelial cell anion transport remains incompletely understood.
Purpose of the Study:
- To investigate the requirement of CFTR expression for anion currents in mouse choroid plexus epithelial cells.
- To characterize the properties of anion conductances in these cells, particularly in the context of cystic fibrosis (CF).
Main Methods:
- Whole cell patch-clamp electrophysiology was employed on freshly isolated tissue from wild-type and CFTR-mutant (Cftrm1cam) mice.
- Anion currents were studied in the presence and absence of cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) stimulation.
- Volume-activated currents were induced by cell swelling and characterized by their ionic selectivity and pharmacological properties.
Main Results:
- A Cl(-)-selective, inward-rectifying conductance was activated by cAMP-PKA in both wild-type and CF cells, with no significant differences observed between genotypes.
- Small outward currents were not modulated by cAMP-PKA in either wild-type or CF cells.
- Volume-activated, Cl(-)-selective currents were observed in both wild-type and CF cells, exhibiting Ca2+ independence and ATP dependence, with no significant genotypic differences in their magnitude.
Conclusions:
- CFTR does not contribute to the basal or cAMP-PKA-stimulated whole-cell conductance in mouse choroid plexus epithelial cells.
- CFTR does not regulate other identified anion conductances, including volume-activated currents, in these cells.
- These findings suggest that alternative or redundant mechanisms mediate anion transport in the choroid plexus epithelium.