The contribution of cholinergic detrusor excitation in a pig model of bladder hypocompliance

Abstract

Objective To investigate the role of cholinergic excitation in mediating changes in detrusor compliance (manifested on conventional cystometry as an incremental rise in detrusor pressure as bladder volume increases) under conditions of propofol-sedation in the pig. Materials and methods Consecutive cystometrograms (CMGs) were obtained from eight female Large White pigs at a bladder ®lling rate of 50 mL/min. The ®rst CMG was obtained while the pig was awake and unsedated. Two subsequent CMGs were obtained after light to moderate sedation with propofol (2±8 mg/kg/ h) before and after the administration of intravenous atropine (0.02 mg/kg). Results All bladders were highly compliant over the volumes instilled (before sedation) with a maximum pressure during the ®lling phase of 0.9 cmH 2 O and a compliance of 943 mL/cmH 2 O. After sedation with propofol, the maximum pressure during the ®lling phase increased to 14 cmH 2 O with a compliance of 69 mL/cmH 2 O. Atropine antagonized this change in compliance; after sedation and atropine, the maximum pressure during the ®lling phase decreased to 4 cmH 2 O (P<0.05) and the compliance increased to 337 mL/cmH 2 O (P<0.05). Conclusion The decrease in compliance seen in the pig bladder after sedation with propofol is mediated via muscarinic excitation. This probably occurs as a result of low-level tonic release of acetylcholine by the efferent parasympathetic nerves. The existence of such efferent excitatory activity during the storage phase in the overactive human bladder might explain the ef®cacy of bladder-selective muscarinic antagonists in a proportion of patients with detrusor hyper-re¯exia and instability.

Arrays for chronic functional microstimulation of the lumbosacral spinal cord

“…This intravenous (IV) anesthetic is short-acting and the depth of the anesthesia is easily adjusted by adjusting the rate of infusion. In addition, the animals recover quickly after the anesthesia is [33]. The cat's bladder was catheterized with a double-lumen catheter with one lumen opening into a side port (Braintree Scientific model DLR-4, 1.25 mm OD).…”

Role of gap junctions in spontaneous activity of the rat bladder

“…However, when spinal cord connections to the bladder were maintained, TTX enhanced the activity (14,15). This suggests that spontaneous activity might have an origin within the bladder (11) but that the spinal cord exerts an inhibitory control.…”

Effects of high frequency deep brain stimulation on urine storage and voiding function in conscious minipigs

“…Another study in larger pigs with a weight that ranged from 49 to 65 kg (mean weight not reported) using a ¢lling rate more similar to ours of 50 ml/min found an average cystometric capacity of 700 ml (10.8^14.3 ml/ kg) [Mills et al, 2000]. Whether the di¡erence in capacity between normal pigs and the MPTP-pigs receiving deep brain stimulation is related to the stimulation or the MPTP-intoxication is a matter of speculation.…”