EFFECT OF NEDOCROMIL SODIUM ON NEUROGENIC MECHANISMS IN-VITRO

We have developed a guinea pig model that allows monitoring of single afferent nerve fiber activity after stimulation of tracheal nerve endi ngs with various stimuli. Action potentials from nodose or jugular neu rons are recorded extracellularly. Previous experiments have shown tha t the excitability of the nerve endings to, for example, mechanical st imuli can be increased by antigen challenge of presensitized guinea pi gs. Nedocromil sodium 10(-4) mol/L significantly reduced by more than 50% the generation of action potentials in C fibers in response to sti mulation by capsaicin. The precise mechanism is not known, although th e membrane depolarization induced by capsaicin was reduced in the pres ence of nedocromil sodium. This agent did not have a generalized inhib itory effect on afferent excitability because it had no effect on sens itivity to electrical or mechanical stimuli. Nedocromil sodium did not affect the generation of action potentials in A delta and C fibers in the presence of hypertonic saline solution.