[Electrophysiologic studies of local ion transport changes in the tracheal wall in vitro]

It is generally accepted that stimulation of sensory receptors of airways provokes cough reflex and liberates neuropeptides which influence the smooth muscle tonus, mucosal blood flow and secretion of mucus. The study tests the hypothesis that mechanical stimulation of airway wall changes also epithelial ion transport and in this way influences physiological performance of the organ. The global evaluation of ion transport was accomplished by measurements of transepithelial electrical potential difference and resistance of the front part of a wall of isolated rabbit trachea which was mounted in an Ussing apparatus (Fig. 1, Tab. 1). In response to a gentle rinsing of tracheal mucosal surface by isoosmotic bathing fluid it reacted with transient increases of both potential difference and current (Fig. 2, Tab. 2). Gentle touching of the mucosal surface also elicited changes and a stepwise return to the baseline value of potential difference. Application of the stimuli from the antilumenal side usually but not invariably failed to produce any changes in potential difference or current. Measurements of mechanosensitive changes of electrical potential difference in secretory or reabsorptive states of tracheal wall (modelled by inhibition of sodium or chloride transepithelial transport) revealed that according to functional status of epithelium sodium or chloride ions transport changes are responsible for the reactions (Fig. 4). We put forward the hypothesis that mechanosensitive changes of ion transport of airways in vivo could be responsible for adequate changes in the status of respiratory tract epithelial fluid lining during the cough reflex (Fig. 5).