Ionic support of the cough reflex

The aim of this study was to determine the role ofintra-wall nervous and neurohormonal system in the control of airway transport of sodium and chloride ions, as well as to identify regulating mechanisms having an effect on the permanent electric potential of airway tissue, named the transepithelial electric potential (PD) and on reversible changes of this potential (dPD). Using amiloride, a sodium ion blocker, and bumetanide, a blocker of the chloride ion co-transport system, the importance oftransepithelial sodium and chloride ion transport for support of the cough reflex was determined. The conditions were identified for examination of chloride secretion in the airways presented as the chemical isolation of chloride currents with the use of amiloride.

The experimental material consisted of 135 fragments of trachea wall obtained from 45 animals. The experiments were directed at measurements of PD of the isolated tracheal wall placed in Ussing chamber where this tissue formed an interface between two half-chambers filled with an isoosmotic polyelectrolyte solution. The main procedure for irritation of sensory receptors in the airways utilized ajet from a peristaltic pump directed to the mucous surface of the isolated trachea. The jet fluid was analogous to the one in the chamber or it was modified as the experimental conditions required.

Transepithelial transport of sodium ions in the trachea exerted a regulatory effect modulating the transepi- thelial difference of electric potentials, as well as inducing hyperpolarisation after mechanical stimulation when at 40% the sodium transport is the exclusive carrier of the hyperpolarisation reaction.