A major function of respiratory tract (RT) epithelial cells is the maintenance of unobstructed airways, a goal achieved by mucociliary clearance. Ciliary activity provides the driving force for mucus propulsion, but the nature of the stimulus-response coupling that regulates ciliary beat frequency is not well understood. The possibility that mechanical interaction between the mucus and ciliated cell may act as a specific control signal was evaluated by examining the effect of mechanical stimulation on cultured RT cells while monitoring ciliary beat frequency with a photoelectronic technique.1 Mechanical stimulation of the apical surface of a single ciliated cell in culture with a glass microprobe elevated the ciliary beat frequency, not only of the stimulated cell, but also of adjacent cells. This resulted in a wave of increased beat frequency spreading across the culture.2,3 The increase in beat frequency of each cell occurred after a lag-phase that was proportional to the distance of the cell from the stimulated cell. Stimulation of a nonciliated cell also initiated an increase in beat frequency of adjacent ciliated cells. Preliminary evidence suggested that these responses were mediated by elevations in [Ca2+]i.2 Consequendy, video imaging techniques were used to monitor the fluorescence of the Ca2+-specific dye fura-2 to quantitate the spatial-temporal changes in [Ca2+]i.4 A single mechanical stimulus to either a ciliated or nonciliated cell immediately induced an increase in [Ca2+]i at the site of contact that then spread throughout the cell. After a short delay of about 0.5 s, a wave of increasing [Ca2+]i occurred in adjacent cells, spreading from one end of the cell to the other. This increase in [Ca2+], or Ca2+ wave, continued to spread through the cell culture in a cell-by-cell manner travelling across 4 to 7 cells in all directions (Fig 1, a). The increase in [Ca2+]i was correlated with, but always preceded, the increase in ciliary beat frequency.
|Number of pages||3|
|Publication status||Published - 31 Mar 1992|