Respiratory response to baroreceptor stimulation and spontaneous contractions of the urinary bladder

Spontaneous contractions of the urinary bladder (SBCs) and experimental ele vations of carotid sinus pressure (CSP) have been shown to result in respir atory inhibition with preferential reduction in hypoglossal (HG) nerve acti vity as compared with that of phrenic nerve discharge. We assessed the inte raction between these respiratory inhibitory stimuli in decerebrate, vagoto mized, paralyzed and artificially ventilated cats. We denervated the right carotid sinus and pressurized the isolated left carotid sinus region within the linear range of the baroreflex, while maintaining systemic arterial pr essure at similar to 100 mmHg. We monitored the HG and phrenic nerve respon ses to SBCs, to elevations in CSP between SBCs, and to elevations in CSP du ring SBCs. Our results show that superimposing these stimuli results in res piratory inhibition, especially of HG activity, that exceeds that resultant from either stimulus alone. We speculate that the combined presence of SBC s and episodic hypertension may contribute to the development of periodic b reathing or obstructive apnea, particularly during sleep. (C) 2001 Elsevier Science B.V. All rights reserved.