CILIARY BEAT FREQUENCY AT 6 LEVELS OF THE RESPIRATORY-TRACT IN COW, DOG, GUINEA-PIG, PIG, RABBIT AND RAT

1. The ciliary beat frequency (CBF) of six animal species from six reg ions of the respiratory tract were measured: inferior turbinate, nasop harynx, the upper part of trachea from first to second cartilage, the lower part of trachea, main bronchus and subsegmental bronchi. Cow, pi g, dog, rabbit, guinea-pig and rat were studied. 2. There were no sign ificant differences in the CBF values between cow, pig and dog, and th e ciliary activity was essentially the same (11.3-16.9 Hz) in ail part s of the respiratory tract. 3. In the rat, the CBF was slower, especia lly in subsegmental bronchi (6.8 Hz). 4. In general, CBF was higher in upper than lower airways, with the exception of guinea-pig. 5. Signal quality was the highest in guinea-pig tissue, whereas rat tissue prod uced the signal with the widest variation in CBF and the highest propo rtion of distorted waveforms. 6. Therefore, for studying drug effects on ciliary activity, guinea-pig seems to be a more suitable animal tha n the more commonly used rabbit or rat. In drug comparisons, the same part of the respiratory tract and the same animal species should be us ed.