Spatiotemporal Mapping of the Contracting Gravid Uterus of the Rabbit Shows Contrary Changes With Increasing Gestation and Dosage With Oxytocin.

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 ß2 adrenergic receptor agonist salbutamol thus reducing area of contraction, and the duration and distance of propagation.

Pharmacological modulation of the spatiotemporal disposition of micromotions in the intact resting urinary bladder of the rabbit; their pattern is under both myogenic and autonomic control.

OBJECTIVES: To 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. METHODS: Spatiotemporal 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. RESULTS: The 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. CONCLUSIONS: The 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.

Characterisation of the contractile dynamics of the resting ex vivo urinary bladder of the pig.

OBJECTIVES: To characterise the area and movements of ongoing spontaneous localised contractions in the resting porcine urinary bladder and relate these to ambient intravesical pressure (Pves ), to further our understanding of their genesis and role in accommodating incoming urine. MATERIALS AND METHODS: We 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 Pves and cyclic changes in Pves with parameters derived from spatiotemporal maps. RESULTS: Contractile 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 Pves (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 Pves and the areas undergoing PPCs increased after a sudden increase in Pves but the frequency of cycles of Pves and of origin of PPCs did not change. Peaks in Pves 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. CONCLUSIONS: The origin and duration of PPCs influence both Pves and cyclic variation in Pves . Hence, propagating rather than stationary areas of contraction may contribute to overall tone and to variation in Pves . 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.

Topical diltiazem before transrectal ultrasonography-guided biopsy of the prostate: a randomized controlled trial.

BACKGROUND: Injection of local anaesthetic agents around the prostatic nerve bundles during transrectal ultrasonography (TRUS) biopsy of the prostate has shown to reduce the pain associated with the procedure. It has been shown that some of the discomfort associated with the procedure is secondary to spasm of the anal sphincter. Topical diltiazem can relax the anal sphincter. Our aim was to evaluate the use of topical diltiazem cream as an adjunct to periprostatic nerve block in reducing pain associated with TRUS-guided prostatic biopsy. METHOD: Between September 2009 and September 2010, 114 patients were enrolled in the trial (from two centres). Patients undergoing TRUS biopsy of prostate were randomized into diltiazem and placebo groups. Patients were asked to fill out a questionnaire at the end of the procedure. The questionnaire enquired about discomfort associated with various parts of the procedure using a 10-cm visual analogue scale (VAS). RESULTS: For discomfort due to the presence of the probe, pain during the biopsy and overall pain prior to leaving the department, mean VAS was higher for the placebo group, but the difference was not statistically significant. CONCLUSION: Diltiazem cream has a better side effect profile than glyceryl trinitrate cream and is better tolerated. Although we have demonstrated trends favouring diltiazem use as an adjunct to local anaesthetic in TRUS biopsy of the prostate, this did not reach a statistically significant level. The pain scores associated with TRUS biopsy in our cohort were lower than those in the published literature. This phenomenon might have contributed to the results observed in this trial.

Non-invasive urodynamics predicts outcome prior to surgery for prostatic obstruction.

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.