Inspiration closure reflex: The effect of respiration on intrinsic sphincters

Abstract

The functions of the lower esophageal sphincter (LES) and internal urethral sphincter (IUS) have not been reported during voluntary and involuntary respiratory maneuvers. In this study we performed a prospective barium videofluoroscopy study (BSV) of the LES on 4 healthy adult men during voluntary cough (VC), laryngeal expiration reflex (LER), breath-hold maneuvers, and normal inspiration. One subject had fiber-optic pressure catheters placed in the LES and IUS, and electromyographic recording of the right T7-8 intercostals during respiration. BSV showed closure and relaxation of the LES corresponding to the inspiration and expiration of VC. The LES was patent during the LER. There was closure of the LES during the deep inspiration/breath-hold event. Pressure catheters in the LES and IUS showed increased pressure during inspiration. These observations suggest that pulmonary inspiration afferents elicit a patterned reflex motor response in the LES and IUS, referred to as the inspiration closure reflex (ICR).