ObjectivesTo characterise the area and movements of ongoing spontaneous localised contractions in the resting porcine urinary bladder and relate these to ambient intravesical pressure (P ves ), to further our understanding of their genesis and role in accommodating incoming urine. Materials and MethodsWe used image analysis to quantify the areas and movements of discrete propagating patches of contraction (PPCs) on the anterior, anterolateral and posterior surfaces of the urinary bladders of six pigs maintained ex vivo with small incremental increases in volume. We then correlated the magnitude of P ves and cyclic changes in P ves with parameters derived from spatiotemporal maps. ResultsContractile movements in the resting bladder consisted only of PPCs that covered around a fifth of the surface of the bladder, commenced at various sites, and were of %6 s in duration. They propagated at around 6 mm/s, mainly across the anterior and lateral surface of the bladder by various, sometimes circular, routes in a quasi-stable rhythm, and did not traverse the trigone. The frequencies of these rhythms were low (3.15 cycles/min) and broadly similar to those of cyclic changes in P ves (3.55 cycles/min). Each PPC was associated with a region of stretching (positive strain rate) and these events occurred in a background of more constant strain. The amplitudes of cycles in P ves and the areas undergoing PPCs increased after a sudden increase in P ves but the frequency of cycles of P ves and of origin of PPCs did not change. Peaks in P ves cycles occurred when PPCs were traversing the upper half of the bladder, which was more compliant. The velocity of propagation of PPCs was similar to that of transverse propagation of action potentials in bladder myocytes and significantly greater than that reported in interstitial cells. The size of PPCs, their frequency and their rate of propagation were not affected by intra-arterial dosage with tetrodotoxin or lidocaine. ConclusionsThe origin and duration of PPCs influence both P ves and cyclic variation in P ves . Hence, propagating rather than stationary areas of contraction may contribute to overall tone and to variation in P ves . Spatiotemporal mapping of PPCs may contribute to our understanding of the generation of tone and the basis of clinical entities such as overactive bladder, painful bladder syndrome and detrusor overactivity.

Objective To assess whether the penile cuff non‐invasive urodynamic test serves as an effective diagnostic tool for predicting outcomes prior to disobstructive surgery for men presenting with voiding lower urinary tract symptoms. Patients with proven urodynamic obstruction do better after surgery. The current gold standard, invasive pressure‐flow studies, imposes cost, resource demand, discomfort and inconvenience to patients. Patients and Methods Patients undergoing surgery for prostatic obstruction at Palmerston North Hospital had pre‐operative non‐invasive urodynamics and completed an International Prostate Symptom Score (IPSS). Catheterised patients were excluded. Two months post‐operatively they completed a further IPSS score. An improvement of seven or greater was defined as a clinically successful outcome. Results were compared with the outcome predicted by the nomogram supplied with the urodynamic device. Results Data was obtained for 62 patients with mean age 70 years (range 49 to 86 years; SD 9 years). Follow‐up was complete for all patients. Thirty‐eight patients underwent transurethral resection and 24 holmium laser enucleation of the prostate. Mean IPSS score was 21 (range 5 to 35; SD 6) pre‐operatively and 11 (range 1 to 31; SD 9) post‐operatively. Thirty‐five patients were predicted obstructed and 27 not obstructed. 94% of those predicted obstructed had a successful outcome (p < 0.01). 70% predicted as not obstructed did not have a successful outcome after surgery (p < 0.01). Conclusion The penile cuff test is an exciting adjunct in the decision to proceed to surgery for prostatic obstruction. Patients predicted to be obstructed have an excellent likelihood of a good surgical outcome, yet 30% of those shown not to be obstructed will still do well. Whilst numbers in our study are small, outcomes compare favourably with published results on invasive urodynamic methods.

The dynamics of propagating myogenic contractions in the wall of the resting ex vivo urinary bladder of the rabbit were characterized by spatiotemporal maps and related to cyclic variation in intravesical pressure (P). Patches of propagating contractions (PPCs) enlarged and involuted in near synchrony with peaks in P [mean 3.85  ± 0.3 cycles per minute (cpm)] and were preceded by regions of stretch. The maximum area of the bladder undergoing contraction (55.28 ± 2.65%) and the sizes of individual PPCs (42.61 ± 1.65 mm) coincided with the peak in P PPCs originated and propagated within temporary patch domains (TPDs) and comprised groups of nearly synchronous cyclic propagating individual contractions (PICs). The TPDs were located principally along the vertical axis of the anterior surface of the bladder. The sites of origin of PICs within PPCs were inconsistent, consecutive contractions often propagating in opposite directions along linear maps of strain rate. Similar patterns of movement occurred in areas of the anterior bladder wall that had been stripped of mucosa. P varied cyclically with area of contraction and with the indices of aggregation of PPCs, indicating that they grew by peripheral enlargement and collision without annihilation. The synchronization of PICs within PPCs was sometimes lost, uncoordinated PICs then occurring irregularly (between 4 and 20 cpm) having little effect on P We postulate that the formation and involution of PPCs within a TPD resulted from cyclic variation in excitation that increased the incidence and distance over which component PICs propagated.

Spontaneous and oxytocin induced contractile activity was quantified in the bicornuate uteri of pregnant rabbits maintained in situ, using data from two- and uni- dimensional video spatiotemporal maps (VSTM) of linear and area strain rate and compared statistically. Spontaneous contractions occurred over a range of frequencies between 0.1 and 10 cpm, in gravid animals at 18–21 and at 28 days of gestation, and propagated both radially and longitudinally over the uterine wall overlying each fetus. Patches of contractions were randomly distributed over the entire surface of the cornua and were pleomorphic in shape. No spatial coordination was evident between longitudinal and circular muscle layers nor temporal coordination that could indicate the activity of a localized pacemaker. The density and duration of contractions decreased, and their frequency increased with the length of gestation in the non-laboring uterus. Increasing intravenous doses of oxytocin had no effect on the mean frequencies, or the mean durations of contractions in rabbits of 18–21 days gestation, but caused frequencies to decrease and durations to increase in rabbits of 28 days gestation, from greater spatial and temporal clustering of individual contractions. This was accompanied by an increase in the distance of propagation, the mean size of the patches of contraction, the area of the largest patch of contraction and the overall density of patches. Together these results suggest that progressive smooth muscle hypertrophy and displacement with increasing gestation is accompanied by a decrease in smooth muscle connectivity causing an increase in wall compliance and that oxytocin restores connectivity and decreases compliance, promoting volumetric expulsion rather than direct propulsion of the fetus by peristalsis. The latter effects were reversed by the β2 adrenergic receptor agonist salbutamol thus reducing area of contraction, and the duration and distance of propagation.

ObjectivesTo explore and characterize the disposition and dynamics of micromotions in the wall of the intact resting teradotoxinized urinary bladder of the rabbit before and after the administration of adrenergic and cholinergic pharmaceutical agents. MethodsSpatiotemporal maps and related intravesical pressure were used to analyse propagating patches of contractions (PPCs) and their component individual myogenic contractions [propagating individual contractions (PICs)] in the wall of the tetradotoxinized urinary bladder. ResultsThe bladder wall exhibited two contractile states that were of similar frequencies to those of the two types of electrophysiological discharge described in previous studies; the first, in which cyclic PPCs predominated, the second in which small irregular PICs predominated. The addition of carbachol increased the size, frequency, speed and distance of propagation of PPCs, whereas the addition of isoprenaline temporarily halted the incorporation of PICs into PPCs, and reduced patch size and total area undergoing contraction. The RhoA kinase (ROCK) inhibitor Y-27632 reduced both largest patch index and mean patch size. Both carbenoxolone and ROCK inhibition decreased the duration of PPCs. Carbenoxolone also prolonged duration and accelerated PPC propagation velocity. The authors postulate that these differences arise from differing effects of these agents on myocytes and interstitial cells within the stress environment of the bladder, influencing the development, coordination and propagation of PPCs. ConclusionsThe timings and structure of spontaneous micromotions in the wall of the isolated bladder change when it is treated with sympathetic/parasympathetic agonists and with myogenically active agents. Correspondingly, disorders of bladder wall contraction may result from disorders of either neurogenic or myogenic signalling and may be amenable to treatment with combinations of agents that influence both.