Electrophysiological evaluation of lidocaine effect on ion transport in airways in isolated trachea of rabbit
Artur Mościbroda, Bolesław Banach
Med Sci Monit 1999; 5(3): BR399-404
Cough is a defence reflex removing harmful particles from airways outside the body. In vitro studies performed so far have proved that apart from reflex mechanisms, there is an ion mechanism adjunctive to cough. As the insertion of fibroscope to bronchial lumen triggers cough reflex, the aim of our study was to establish the effect of anaesthesia with lidocaine on ion reactions in airway epithelium, which would allow for their investigation in the future. The effect of compounds blocking nervous conduction (used in medicine as anaesthetic agents) upon the function of nerve and sensory endings of airway epithelial receptors is nearly completely obscure. Sensory endings play double role, i.e. they generate nervous afferent impulses and release locally-acting neuropeptides, while complex mutual interrelationships modulating both these functions were observed. Our study investigated the effect of lidocaine on two functionally different components of transepithelial electric potential (PD) of tracheal wall placed in modified Ussing apparatus. We took into consideration immediate lidocaine effects as opposed to its activity after 60-minute incubation in control conditions and after mechanical stimulation of epithelium. The results indicate that the effect of lidocaine on transepithelial potential depends on its duration and the mode of its delivery to the tissue. Lidocaine causes significant decline of spontaneous transepithelial potential (constant PD component), while it inhibits hyperpolarisation after mechanical stimuli (varying PD component) to lower extent. Depending on ion transport processes, the mechanisms of airway cleaning are not eliminated completely by lidocaine activity. Nervous sensory endings in airways influence cleaning processes and thus, these issues are of practical importance since local anaesthetics are used during diagnostic investigations as well as in the therapy of airway disturbances.
Keywords: in vitro studies, Ion Transport, Trachea, Lidocaine