Urine composition in pigs is regulated in both the ureter and the bladder.

The former perception of the urothelium as an impermeable barrier has been revised during the last decade, as increasing evidence of changes in urine composition during its passage of the urinary tract has been presented. Since differences in urothelial permeability between upper and lower urinary tract have been found, our aim is to demonstrate whether changes in urine composition occur during passage through the ureter. We studied consecutive urine samples from both renal pelvises in six pigs and compared them to samples from the bladder and distal ureter. We further sampled urine during storage in the bladder at a fixed volume. All samples were analysed by measuring osmolality and pH, along with the concentration of the following parameters: Na(+), K(+), Cl(-), creatinine, urea. Urine alkalinity increased significantly during passage of the ureter. Creatinine concentration, pH and K(+) increased significantly during the passage from pelvis to the bladder. All other parameters increased non-significantly during the passage to the bladder. The increase in concentration was more pronounced at low concentrations in the pelvis. During storage in the bladder, there was a significant increase in urea concentration. Changes in the composition of urine occur during its passage from the renal pelvis to the bladder and during storage in the bladder. Despite the brief transit time, significant changes in alkalinity were found already during passage through the ureter.

Aquaporin expression in the fetal porcine urinary tract changes during gestation.

The expression of aquaporins (AQPs) in the fetal porcine urinary tract and its relation to gestational age has not been established. Tissue samples from the renal pelvis, ureter, bladder and urethra were obtained from porcine fetuses. Samples were examined by RT-PCR (AQPs 1-11), QPCR (AQPs positive on RT-PCR), and immunohistochemistry. Bladder samples were additionally examined by Western blotting. RNA was extracted from 76 tissue samples obtained from 19 fetuses. Gestational age was 60 (n=11) or 100 days (n=8). PCR showed that AQP1, 3, 9 and 11 mRNA was expressed in all locations. The expression of AQP3 increased significantly at all four locations with gestational age, whereas AQP11 significantly decreased. AQP1 expression increased in the ureter, bladder and urethra. AQP9 mRNA expression increased in the urethra and bladder, but decreased in the ureter. AQP5 was expressed only in the urethra. Immunohistochemistry showed AQP1 staining in sub-urothelial vessels at all locations. Western blotting analysis confirmed increased AQP1 protein levels in bladder samples during gestation. Expression levels of AQP1, 3, 5, 9 and 11 in the urinary tract change during gestation, and further studies are needed to provide insights into normal and pathophysiological water handling mechanisms in the fetus.

What is a representative voiding pattern in children with lower urinary tract symptoms? Lack of consistent findings in ambulatory and conventional urodynamic tests.

BACKGROUND: Conventional urodynamics (CU) is a highly standardized evaluation of lower urinary tract function. However, in pediatric patients there is concern that the reliability of measurements could be influenced by development effects and measurement variability, as well as by the unfamiliar clinical environment. Ambulatory urodynamics (AU) provides an alternative to this - it uses natural filling, is measured over a prolonged period, and is conducted in a child-friendly environment. OBJECTIVE: The aim of this study was to conduct a comparative analysis of AU and CU to evaluate the consistency in voiding patterns obtained with these two methods of urodynamic testing. STUDY DESIGN: Urodynamic parameters obtained by AU and CU methods in 50 pediatric patients aged >5 years were retrospectively analyzed. Voiding patterns were categorized into six types: coordinated contraction, detrusor after-contraction, fluctuated contraction, pre-void contraction, relief voiding, and weak or absent contraction. Voiding patterns were used to determine the repeatability within urodynamic tests and to identify consistency between AU and CU tests. Five urodynamic parameters were quantified and compared between AU and CU: voided volume, flow rate, maximum detrusor pressure, and detrusor pressure at peak flow rate. For inter-observer variation analysis, 100 voiding curves were randomly selected and categorized by two independent observers; inter-observer agreement was evaluated using the kappa statistic. RESULTS: A single pattern of voiding was identified in five patients using AU and 37 using CU. Consistency of a single pattern between AU and CU was identified in three patients, and consistency between a predominant pattern with AU, defined by one type of voiding occurring >50% of one's voids, and a single pattern with CU was identified in 10 patients (summary table). Flow rates were similar between methods; however, higher maximum detrusor pressure and detrusor pressure at peak flow and lower voided volume were recorded with AU. DISCUSSION: AU resulted in more diverse voiding patterns. Along with the differences in measured urodynamic parameters challenges the application of findings from one method to form a clinical diagnosis. Furthermore, CU may not be as sensitive as AU to the variability in lower urinary tract pathophysiology. CONCLUSIONS: More diverse voiding patterns were identified in AU compared with CU, with a lack of consistency in identified voiding pattern in both methods. Therefore, the urodynamic findings in children may have to be analyzed in more detail, taking the variations into account.