Intracellular Recording from Posterior Cricoarytenoid Motoneurons in the Rat

The ability to maintain coordinated vocal cord abduction and upper airway patency is dependent on the integrity of the posterior cricoarytenoid (PCA) motoneurons and their multiple neural connections. Study of the PCA motoneurons represents the initial step in understanding the complex mechanisms responsible for coordinated vocal cord abduction and may provide an insight into the possible pathological processes underlying the various clinical presentations of vocal cord dysfunction. Intracellular recordings were made from 11 PCA motoneurons in Sprague-Dawley rats, which all showed an inspiratory augmenting discharge pattern that is also characteristic of phrenic nerve activity. The resting membrane potential was −56 ± 11 mV. Two PCA motoneurons were injected with Neurobiotin to demonstrate neuronal morphology, which was found to be similar to that obtained by retrograde labeling with cholera toxin B subunit. The technique described for intracellular recording of PCA motoneurons should allow more detailed morphological, electrophysiological, and immunohistochemical information to be obtained, to thereby identify some of the factors responsible for maintaining normal function of the PCA muscle.