Localized cytosolic alkalization and its functional impact in ciliary cells

Area of Science:

• Cell Biology
• Respiratory Physiology

Background:

• Airway epithelium relies on ciliary function for mucus clearance.
• Cytosolic pH regulation is critical for cellular processes, including ciliary function.

Purpose of the Study:

• To investigate the distinct pH regulatory mechanisms within airway ciliary cells.
• To determine the effect of localized cytosolic pH changes on ciliary beat frequency (CBF).

Main Methods:

• Confocal microscopy was used to visualize cytosolic pH.
• Extracellular pH (pHo) was varied, and ammonium chloride (NH4Cl) was applied to induce pH changes.
• Ciliary beat frequency (CBF) was measured.

Main Results:

• Airway ciliary cells exhibit two distinct cytosolic pH regions: a buffered bulk and a pHo-sensitive region near the ciliary membrane.
• Changes in extracellular pH (pHo) did not affect CBF.
• Localized alkalization induced by NH4Cl significantly enhanced CBF.
• Calmodulin and protein kinase A (PKA) were essential for the NH4Cl-induced CBF enhancement.

Conclusions:

• Airway epithelium can generate localized cytosolic alkalization near cilia, enhancing CBF.
• This enhancement is mediated by calmodulin and PKA activation, involving synergistic effects of elevated cytosolic pH and Ca2+.
• This mechanism may play a role in airway clearance under specific physiological conditions.