Dorsal Medulla Inspiratory Neurons Contribute to Increased Inspiratory Drive during Swallow

Abstract

Schluckatmung, or swallow breath is believed to be an evolutionarily preserved inspiratory drive from deglutition to eupnea. This inspiratory motor drive creates a net negative trans‐esophageal pressure that promotes bolus movement across the upper esophageal sphincter. A multi‐channel electrode array was used to record dorsal respiratory group neurons in anesthetized, spontaneously breathing cats. Swallowing was induced by injection of water into the oropharynx. Electromyograms (EMG) were recorded from pharyngeal, laryngeal, and chest wall muscles, and intra‐esophageal pressure was recorded from the mid‐thoracic esophagus. A total of 104 inspiratory (I) and expiratory (E) phasic neurons were recorded in 6 animals during breathing and swallow. Approximately 90% of I neurons increased their firing frequency during swallow, and approximately 80% of E neurons decreased their firing frequency during swallow. The increased firing rate of I neurons was associated with costal diaphragm and parasternal EMG bursts along with a negative esophageal pressure during swallow. Previous work has shown low activity of I neurons during swallow in the ventral respiratory column. We conclude that increased dorsal medullary inspiratory neuron activity contributes to enhanced inspiratory drive during swallow. Supported by HL 111215(K99/R00) & HL 103415