Figure 2.

Typical evoked micturition response. (A) As the bladder is filled there is a gradual rise in pressure and a tonic increase in activity of the EUS–EMG. This pressure rise triggers a void with a generalized bladder contraction, a series of bursts on the EUS–EMG trace (mirrored by small oscillations in intravesical pressure) and the ejection of urine. Note at the end of the void as the tonic sphincter activity returns to baseline and the sphincter closes, the still contracting bladder generates a spike of pressure as it contracts iso-volumetrically (also refer to Videos S1 and S2 in Supplementary Material). (B) Expanded time scale showing increase in EUS activity during filling, followed by discrete bursting activity during voiding (inset: three individual bursts), in time with bladder pressure oscillations, where each burst is followed by a mini pressure rise (superimposed on inset), characteristic of the rat voiding pattern. Note in (A), the preparation also shows a eupnoeic pattern of phrenic nerve discharge with respiratory sinus arrhythmia seen in the heart rate trace consistent with intact brainstem–autonomic coupling yet none of these variables (nor perfusion pressure) are altered during the micturition reflex.