Enhancement of airway ciliary beating mediated via voltage-gated Ca2+ channels/α7-nicotinic receptors in mice

• Published in: Pflügers Archiv Vol. 474; no. 10; pp. 1091 - 1106
• Main Authors: Saitoh, Daichi, Kawaguchi, Kotoku, Asano, Shinji, Inui, Toshio, Marunaka, Yoshinori, Nakahari, Takashi
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.10.2022; Springer Nature B.V
• Subjects: Acetylcholine receptors (muscarinic); Acetylcholine receptors (nicotinic); Autocrine signalling; Biomedical and Life Sciences; Biomedicine; Calcium (intracellular); Calcium channels; Calcium channels (voltage-gated); Calcium signalling; Cell Biology; Cilia; Experiments; Human Physiology; Immunoblotting; Immunofluorescence; Interleukin 13; Laboratories; Lungs; Molecular Medicine; Neurosciences; Nifedipine; Physiology; Potassium; Pulmonary arteries; Receptors; Respiratory tract; Signal transduction; Signaling and Cell Physiology; Ciliary beating; concentration; Airway; VDCC; Intracellular Ca; α7 nicotinic acetylcholine receptor
• ISSN: 0031-6768; 1432-2013; 1432-2013
• DOI: 10.1007/s00424-022-02724-5

Acetylcholine (ACh), which activates muscarinic ACh receptors (mAChRs) and nicotinic ACh receptors (nAChRs), enhances airway ciliary beating by increasing the intracellular Ca 2+ concentration ([Ca 2+ ] i ). The mechanisms enhancing airway ciliary beating by nAChRs have remained largely unknown, although those by mAChRs are well understood. In this study, we focused on the effects of α7-nAChRs and voltage-gated Ca 2+ channels (Ca V s) on the airway ciliary beating. The activities of ciliary beating were assessed by frequency (CBF, ciliary beat frequency) and amplitude (CBD, ciliary bend distance) measured by high-speed video microscopy. ACh enhanced CBF and CBD by 25% mediated by an [Ca 2+ ] i increase stimulated by mAChRs and α7-nAChRs (a subunit of nAChR) in airway ciliary cells of mice. Experiments using PNU282987 (an agonist of α7-nAChR) and MLA (an inhibitor of α7-nAChR) revealed that CBF and CBD enhanced by α7-nAChR are approximately 50% of those enhanced by ACh. CBF, CBD, and [Ca 2+ ] i enhanced by α7-nAChRs were inhibited by nifedipine, suggesting activation of Ca V s by α7-nAChRs. Experiments using a high K + solution with/without nifedipine (155.5 mM K + ) showed that the activation of Ca V s enhances CBF and CBD via an [Ca 2+ ] i increase. Immunofluorescence and immunoblotting studies demonstrated that Cav1.2 and α7-nAChR are expressed in airway cilia. Moreover, IL-13 stimulated MLA-sensitive increases in CBF and CBD in airway ciliary cells, suggesting an autocrine regulation of ciliary beating by Ca V 1.2/α7-nAChR/ACh. In conclusion, a novel Ca 2+ signalling pathway in airway cilia, Ca V 1.2/α7-nAChR, enhances CBF and CBD and activates mucociliary clearance maintaining healthy airways.