Do pulmonary ionocytes absorb chloride or secrete chloride?
Ian M Thornell1, Lei Lei2, Paul B McCray2,3
1Department of Internal Medicine, Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States.
American Journal of Physiology. Cell Physiology
|December 24, 2024
Summary
Pulmonary ionocytes exhibit dual behavior regarding chloride transport. This review reconciles conflicting findings by examining transepithelial voltages during short-circuit and open-circuit conditions, clarifying ionocyte function.
Area of Science:
- Cellular physiology
- Respiratory system biology
Background:
- Pulmonary ionocytes are crucial for airway surface liquid homeostasis.
- These cells express high levels of the cystic fibrosis transmembrane conductance regulator (CFTR) channel.
- Previous studies show conflicting results regarding chloride (Cl-) transport in ionocytes.
Purpose of the Study:
- To resolve the apparent contradiction in pulmonary ionocyte Cl- transport.
- To elucidate the role of transepithelial voltage in ionocyte function.
- To discuss the regulation of ionocyte absorption and secretion.
Main Methods:
- Review of existing literature on pulmonary ionocyte electrophysiology.
- Analysis of short-circuit current (SCC) and open-circuit conditions.
- Consideration of transepithelial voltage differences.
Main Results:
- Short-circuit current (SCC) measurements suggest Cl- secretion via CFTR.
- Open-circuit conditions without voltage clamp indicate Cl- absorption.
- The discrepancy is explained by differing transepithelial voltages in experimental vs. physiological states.
Conclusions:
- Short-circuit current (SCC) findings do not directly predict physiological ionocyte behavior.
- Basolateral Cl- channels play a key role in controlling ionocyte absorption and secretion.
- Understanding these transport mechanisms is vital for respiratory health research.
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