Effects of local anaesthetics (lidocaine) on the structure and function of ciliated respiratory epithelial cells

Summary— Sampling for nasal or bronchial ciliated cells requires the use of anaesthetic agents, but such drugs may interfere with the morphological or functional results. Lidocaine is the most frequently used local anaesthetic. In order to study the morphological and functional effects of lidocaine hydrochloride, we designed an experimental study on ciliated cells from guinea pig and bovine trachea. On guinea pig tracheal specimens, different lidocaine concentrations (0.05, 0.25 and 1%) were tested. Tracheal rings were immersed in either culture medium alone (control) or in different lidocaine concentrations. Measurements of ciliary beat frequency (CBF) were performed by the stroboscopic method. Tracheal rings were consecutively incubated in culture medium alone and a second set of measurements was performed. Tracheal rings were studied by light microscopy after incubation in either 1% lidocaine or in culture medium alone. On bovine tracheal specimens, a coton wool swab impregnated with different lidocaine concentrations (0, 0.25, 1, 2.5 and 5%) was placed in contact with the tracheal mucosa. Three different kinds of samples were collected: the first one was used to study CBF, the second one (0.1 and 5%) was studied by scanning electron microscope (SEM) and the third (0.1 and 5%) by transmission electron microscopy (TEM). The results on guinea pig specimens show a significant but reversible CBF diminution for concentrations of 0.25 and 1% lidocaine and cellular lesions for the concentration of 1%. On bovine specimens a diminution in CBF for concentrations of 2.5 and 5% lidocaine was shown and the SEM study demonstrated obvious lesions on the epithelial surface treated with the 5% concentration. The TEM study showed morphological alterations on respiratory epithelium (deciliated areas, cytoplasmic vacuoles and mitochondrial swelling) for 5% lidocaine concentration. However the axonemal structure of cilia was normal for control and 5% concentration. We concluded that in vitro lidocaine can inhibit the CBF and that high concentrations of lidocaine can damage the respiratory epithelium but without modifications of the axonemal ultrastructure.