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A Fluorescence-Based Assay of Membrane Potential for High-Throughput Functional Study of Two Endogenous Ion Channels in Two Epithelial Cell Lines
Published on: June 22, 2022
Basolateral chloride current in human airway epithelia
Omar A Itani1, Fred S Lamb, James E Melvin
1Howard Hughes Medical Institute, Univ. of Iowa, Iowa City, IA 52242, USA.
Summary
Airway epithelia possess a novel basolateral chloride (Cl-) conductance, distinct from CFTR, ClC-2, or ClC-3. This pathway is regulated by cAMP and PKC, influencing airway surface liquid homeostasis.
Area of Science:
- Cellular physiology
- Epithelial biology
- Ion transport
Background:
- Airway epithelia maintain airway surface liquid via electrolyte transport.
- Cystic fibrosis transmembrane conductance regulator (CFTR) mediates apical chloride (Cl-) absorption.
- Basolateral Cl- exit pathways in airway epithelia remain poorly understood.
Purpose of the Study:
- To investigate the properties and regulation of basolateral Cl- conductance in human airway epithelia.
- To determine if known Cl- channels (CFTR, ClC-2, ClC-3) contribute to this conductance.
Main Methods:
- Primary cultures of well-differentiated human airway epithelia were used.
- Electrophysiological techniques measured basolateral membrane Cl- currents.
- Pharmacological inhibitors and signaling pathway modulators were employed.
Main Results:
- A DIDS-sensitive Cl- current was identified at the basolateral membrane.
- The current exhibited linear current-voltage relationship and halide selectivity (Cl- > Br- >> I-).
- cAMP, PKC activation, and reduced pH increased the current, while Ca2+ and cell swelling had no effect.
Conclusions:
- Airway epithelia possess a basolateral Cl- conductance independent of CFTR, ClC-2, and ClC-3.
- This conductance is regulated by cAMP and PKC signaling pathways.
- Coordinated apical and basolateral Cl- transport is crucial for transepithelial Cl- movement and airway liquid balance.
