[Measurement of respiratory ciliary beat frequency quantified with high-speed digital microscopy]

To accurately quantify the respiratory cilia activity, a high-speed phase-contrast imaging and ciliary beat frequency (CBF) analysis method were introduced.

Airway ciliated cells, from rabbit trachea, mouse trachea and human nose, were prepared by primary culture of airway epithelial cells. Phase-contrast images were detected with a digital high-speed camera, a progressive scan charge-coupled device(CCD) that provided images (648 pixels x 200 lines) at 240 frames per second (fps). A data analysis approach, which can measure the period [frequency (Hz) = 1/period] of each ciliary beat cycle to match the high temporal resolution of the image acquisition rate, was also introduced.

The high signal-to-noise ratio of gray waveform was obtained by interactively selecting the optimal region of interest. The frequency of each ciliary beat cycle was determined from the period of each cycle of the gray -intensity waveform. At 30 degrees C, the basal CBF (x +/- s(x-)), from mouse, rabbit and human, were (15.6 +/- 0.7) Hz (n = 5), (13.2 +/- 0.9) Hz (n = 7), and (13.4 +/- 1.1) Hz (n = 5), respectively. No statistical difference was found among groups (P > 0.05). In response to extracellular ATP, CBF had a rapid increment that could occur in seconds, a behavior suggesting the necessity of the high temporary resolution data acquisition system.

This ease of recording and replaying high-speed images may be useful in analyzing different phases and forms of ciliary beat patterns and perhaps in the diagnosis of cilia dysfunction-related diseases.