Respiratory motor nerve activities during spontaneous bladder contractions

Abstract

We monitored spontaneous bladder contractions (SBCs) in decerebrate vagotomized paralyzed ventilated cats while recording respiratory motor nerve activities and intravesical pressure under isovolumetric conditions. Phrenic nerve discharge diminished during SBCs, as did the activities of the hypoglossal nerve, the nasolabial branch of the facial nerve, and inspiratory (posterior cricoarytenoid) and expiratory (thyroarytenoid) branches of the recurrent laryngeal nerve. Hypoglossal activity was most strikingly reduced during SBCs, disappearing completely in some animals. The triangularis sterni nerve exhibited an initial decrease, followed by an increase in activity during SBCs, whereas the cranial iliohypogastric nerve showed increased activity. The changes in nerve activities during SBCs could also be elicited by passive distension of the bladder and were abolished by bilateral section of the pelvic nerves. These findings extend the understanding of reflexes originating from the urinary bladder to include a coordinated respiratory response and suggest that these reflexes may compromise upper airway patency under some conditions.