Effects of prostaglandins E1 and E2 on activity in laryngeal and pharyngeal afferent fibers

Prostaglandins (PG) E₁ and E₂ were applied topically to the receptive fields of feline laryngeal and pharyngeal sensory receptors, while action potentials were recorded from single - or few-fiber preparations of the superior laryngeal nerve. When initially dissolved in ethanol, PGs stimulated these sensory receptors. If ethanol was not used as a solvent for the PGs, they did not stimulate the sensory receptors. Similarly, local application of dilute (0.025%, v/v) solutions of ethanol alone excited the receptors, whereas phosphate buffer alone did not. Thus PGE₁ and PGE₂ do not themselves stimulate sensory receptors in the larynx and pharynx. These findings suggest that irritant properties of PGEs on upper airways are attributable to the ethanol used as a solvent.