Effect of hypercapnia on the swallow‐breathing relationship in cats

Abstract

Swallow‐breathing coordination is critical for maintaining a clear airway during the act of swallowing. Swallows can occur during all phases of breathing, however, they are primarily initiated during expiration. The interaction between central pattern generators for swallowing and breathing contribute to this phase preference. While hypercapnia has known effects on the breathing central pattern generator, the effects of elevated CO2 on swallow‐breathing coordination are unknown. We examined the influence of hypercapnia on swallow‐breathing phase preference in the cat. Swallowing was induced in anesthetized spontaneously breathing cats by injection of water into the oropharynx and experiments were conducted under conditions of room air, 5% CO2, or 10% CO2. Electromyogram activity was measured using bipolar electrodes inserted into laryngeal and pharyngeal muscles (mylohyoid, geniohyoid, thyrohyoid, and thyropharyngeus), parasternal muscles and costal diaphragm. In cats breathing room air, 71% of swallows occurred during expiration (E), 12% during inspiration (I), 10% during the transition from inspiration to expiration (I to E), and 7% during the transition from expiration to inspiration (E to I). Under hypercapnic conditions swallows occurred more frequently during inspiration with 80% (5% CO2) and 68% (10% CO2) occurring during either the I or the E to I phases of breathing, and 16% (5% CO2) and 25% (10% CO2) occurring during expiration. These preliminary results suggest hypercapnia may affect swallow‐breathing coordination by causing the initiation of swallow to occur in more inspiratory phases (I and E to I).Support or Funding InformationSupported by R00‐HL 111215, NIH HL 103415, and 1OT20D001983.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.