Characterization of Cough Receptors

Surprisingly little is known about the neural mechanism of cough. Although slow and fast adapting stretch receptors in the air passages have been hypothesized to trigger cough, stimuli that activate these receptors do not induce cough. Recently, a new receptor type responsive to touch and acid—stimuli that also evoke cough—was identified in guinea pigs. Mazzone et al. have further characterized these receptors. The cough receptors are A afferents that arise from the nodose ganglia and terminate in the extracellular matrix between the smooth muscle and epithelial layers of the trachea and larynx. Unlike other cells in the airways, cough receptors expressed the sodium pump 3 subunit, and activity of this pump appeared to cause unique labeling of the receptors with the vital dye FM2–10. An 3selective concentration of the sodium pump inhibitor ouabain reduced cough receptor excitability and cough evoked by acid or touch, without noticeably affecting other sodium-pump-dependent responses. Œ Development/Plasticity/Repair