THE COORDINATION AND INTERACTION BETWEEN RESPIRATION AND DEGLUTITION IN YOUNG-PIGS

The anatomical pathways for inspired air and ingested food cross in th e pharynx of mammals, implying that breathing and swallowing must be s eparated either in space or in time. In this study we investigated the time relationship between swallowing and respiration in young pigs, a s a model for suckling mammals. Despite the high morphological positio n of the larynx in young mammals, allowing liquid to pass in food chan nels lateral to the larynx, respiration and swallowing are not wholly independent events. Although, when suckling on a veterinary teat, the swallows occurred at various points in the respiratory cycle, there wa s always a period of apnea associated with the swallow. Finally, an in crease in the viscosity of the milk altered this coordination, changin g respiratory cycle length and also restricting the relative rate at w hich swallows occurred in some parts of the respiratory cycle. These r esults suggest that the subsequent changes in respiratory activity at weaning, associated with passage of a solid bolus over the larynx, is preceded by the ability of the animal to alter coordination between re spiration and swallowing for a liquid bolus.