Intracellular recording from posterior cricoarytenoid motoneurons in the rat

The ability to maintain coordinated vocal cord abduction and upper airway p atency is dependent on the integrity of the posterior cricoarytenoid (PCA) motoneurons and their multiple neural connections. Study of the PCA motoneu rons represents the initial step in understanding the complex mechanisms re sponsible for coordinated vocal cord abduction and may provide an insight i nto the possible pathological processes underlying the various clinical pre sentations of vocal cord dysfunction. Intracellular recordings were made fr om 11 PCA motoneurons in Sprague-Dawley rats, which all showed an inspirato ry augmenting discharge pattern that is also characteristic of phrenic nerv e activity. The resting membrane potential was -56 +/- 11 mV. Two PCA moton eurons were injected with Neurobiotin to demonstrate neuronal morphology, w hich was found to be similar to that obtained by retrograde labeling with c holera toxin B subunit. The technique described for intracellular recording of PCA motoneurons should allow more detailed morphological, electrophysio logical, and immunohistochemical information to be obtained, to thereby ide ntify some of the factors responsible for maintaining normal function of th e PCA muscle.