Protein Kinase 2ß Is Expressed in Neural Crest-Derived Urinary Pacemaker Cells and Required for Pyeloureteric Contraction.

Nonobstructive hydronephrosis, defined as dilatation of the renal pelvis with or without dilatation of the ureter, is the most common antenatal abnormality detected by fetal ultrasound. Yet, the etiology of nonobstructive hydronephrosis is poorly defined. We previously demonstrated that defective development of urinary tract pacemaker cells (utPMCs) expressing hyperpolarization-activated cyclic nucleotide-gated channel 3 (HCN3) and the stem cell marker cKIT causes abnormal ureteric peristalsis and nonobstructive hydronephrosis. However, further investigation of utPMC development and function is limited by lack of knowledge regarding the embryonic derivation, development, and molecular apparatus of these cells. Here, we used lineage tracing in mice to identify cells that give rise to utPMCs. Neural crest cells (NCCs) indelibly labeled with tdTomato expressed HCN3 and cKIT. Furthermore, purified HCN3+ and cKIT+ utPMCs were enriched in Sox10 and Tfap-2α, markers of NCCs. Sequencing of purified RNA from HCN3+ cells revealed enrichment of a small subset of RNAs, including RNA encoding protein kinase 2ß (PTK2ß), a Ca2+-dependent tyrosine kinase that regulates ion channel activity in neurons. Immunofluorescence analysis in situ revealed PTK2ß expression in NCCs as early as embryonic day 12.5 and in HCN3+ and cKIT+ utPMCs as early as embryonic day 15.5, with sustained expression in HCN3+ utPMCs until postnatal week 8. Pharmacologic inhibition of PTK2ß in murine pyeloureteral tissue explants inhibited contraction frequency. Together, these results demonstrate that utPMCs are derived from NCCs, identify new markers of utPMCs, and demonstrate a functional contribution of PTK2ß to utPMC function.

The effect of extracorporeal shock wave lithotripsy on distribution of interstitial cells of Cajal in rabbit renal pelvis and proximal ureter.

BACKGROUND/AIM: An experimental study was performed to evaluate the effect of extracorporeal shock wave lithotripsy (ESWL) on the distribution of interstitial cells of Cajal (ICC) in rabbit renal pelvis and proximal ureter. MATERIALS AND METHODS: Six New Zealand rabbits were included. Right kidneys were exposed to a total of 3000 shock waves (14 kV) by using an electrohydraulic-type ESWL device. Right sides were allocated as the ESWL group (EG, n = 6) and left sides as the control group (CG, n = 6). Tissues were harvested on day 7. Tissues were examined histopathologically for the presence of edema, inflammation, congestion, hemorrhage, fibrosis, and vascularization. Mast cell tryptase and CD 117 (c-kit) staining was performed for ICC distribution. RESULTS: Although increased tissue edema in renal pelvises and increased inflammation in ureters were observed in EG, no statistical difference was detected between groups (P > 0.05). In CG, positive CD117 staining was detected in 2 renal pelvises and ureters. None of the EG samples showed CD117 staining and no statistical difference was detected between groups (P > 0.05). CONCLUSION: Rabbit does not appear to be a good model for investigating ICCs. ESWL may cause histopathological alterations in the renal pelvis and ureter. Since it has not been statistically proven, reduced contractility of the ureter after ESWL may not be attributed to altered distribution of ICCs in the renal pelvis and ureter.

Uropatía incrustante por Corynebacterium urealiticum: comentarios a partir de tres casos clínicos / Fouling uropathy by Corynebacterium urealyticum: Comments from three clinical cases

La uropatía incrustante es una enfermedad infecciosa del tracto urinario causada por la bacteria urealítica Corynebacterium urealyticum (CU). En nuestra serie (datos no publicados) sólo el 15% de las infecciones por CU produce uropatía incrustante. La formación de incrustaciones de estruvita y apatita en la pared del urotelio puede afectar a pelvis renal (pielitis), uréter, vejiga (cistopatía) y próstata, incluyendo la celda prostática después de resección ("celdopatía"). La pielitis es la más frecuente. La clínica corresponde a la triada orina alcalina, piuria y cristaluria de estruvita. Los pacientes suelen ser inmunodeprimidos o multioperados. El cultivo de orina debe estar dirigido al diagnóstico de CU. La TC es la prueba de imagen de elección. Muestra típicas imágenes de calcificación laminar. El tratamiento de la uropatía incrustante es multimodal. Incluye antibioterapia, acidificación de la orina y cirugía (algunos casos) (AU)

The encrustant uropathy is an infectious disease of the urinary tract caused by urealithic bacteria Corynebacterium urealyticum (CU). In our series (unpublished data) only 15% of CU infections caused encrustant uropathy. Formation of apatite and struvite on the wall of the urothelium can affect renal pelvis (pyelitis), urether, bladder (cystophatie) and prostate, including prostate cell after resection ("cellpathy"). Pyelitis is the most common. Clinical triad corresponds to alkaline urine, pyuria and struvite crystalluria. Patients are usually immunocompromised or or multiple previous surgeries. Urine culture should be directed to the diagnosis of UC. CT is the imaging test of choice. Shows typical images of laminar calcification. Treatment of encrusted uro pathy is multimodal. Includes antibiotics, acidification of urine and surgery (sometimes) (AU)

The merits of cytology in the workup for upper tract urothelial carcinoma - a contemporary review of a perplexing issue.

INTRODUCTION: The importance of upper tract cytology for evaluating tumors is unclear. We correlated upper tract cytology with histologic findings in patients who underwent nephroureterectomy for upper tract urothelial carcinoma (UTUC) at a single tertiary care referral center. MATERIALS AND METHODS: 137 patients underwent nephroureterectomy between 2004 and 2012. 18 patients were excluded (benign tumors, atrophic kidneys with the remaining 119 patients serving as our study population). Upper tract cytology from the renal pelvis and/or ureter were retrospectively reviewed and analyzed with final pathology data in the remaining patients with UTUC. RESULTS: 57% (68/119) had preoperative upper tract cytology collected. 73% (50/68) patients had abnormal cytology (positive, suspicious) with a sensitivity of 74% (which increased to 90% if atypical included), specificity of 50% and a positive predictive value of 98%. High grade tumors were more common than expected (77% high grade vs. 20% low grade). Abnormal cytology did not predict T stage or tumor grade. Interestingly, positive upper tract cytology was found in all of the UTUC CIS specimen. CONCLUSIONS: Upper tract cytology has been utilized to support the diagnosis of upper tract urothelial carcinoma. Our data demonstrates that abnormal cytology correlates well with the presence of disease but does not predict staging or grading in these respective patients.

The merits of cytology in the workup for upper tract urothelial carcinoma - a contemporary review of a perplexing issue

Introduction The importance of upper tract cytology for evaluating tumors is unclear. We correlated upper tract cytology with histologic findings in patients who underwent nephroureterectomy for upper tract urothelial carcinoma (UTUC) at a single tertiary care referral center. Materials and Methods 137 patients underwent nephroureterectomy between 2004 and 2012. 18 patients were excluded (benign tumors, atrophic kidneys with the remaining 119 patients serving as our study population). Upper tract cytology from the renal pelvis and/or ureter were retrospectively reviewed and analyzed with final pathology data in the remaining patients with UTUC. Results 57% (68/119) had preoperative upper tract cytology collected. 73% (50/68) patients had abnormal cytology (positive, suspicious) with a sensitivity of 74% (which increased to 90% if atypical included), specificity of 50% and a positive predictive value of 98%. High grade tumors were more common than expected (77% high grade vs. 20% low grade). Abnormal cytology did not predict T stage or tumor grade. Interestingly, positive upper tract cytology was found in all of the UTUC CIS specimen. Conclusions Upper tract cytology has been utilized to support the diagnosis of upper tract urothelial carcinoma. Our data demonstrates that abnormal cytology correlates well with the presence of disease but does not predict staging or grading in these respective patients. .

Identification of prostaglandin receptors in human ureters.

BACKGROUND: Prostaglandins play an important role in ureteral obstruction, but the detailed expression profiles of the prostaglandin receptors (PTGER1, PTGER2, PTGER3, PTGER4, PTGFR) remain unknown in the different parts of the human ureter. METHODS: The expression pattern of PTGER1, PTGER2, PTGER3, PTGER4 and PTGFR was determined in human distal, mid and proximal ureter and renal pelvis samples using immunohistochemistry (protein levels) and quantitative real-time PCR (mRNA). RESULTS: PTGER1 was highly expressed in most samples irrespective of the ureteral localization; however, urothelial cells had higher levels of PTGER1 than smooth muscle cells. PTGFR was also moderately to strongly expressed in urothelial and smooth muscle cells. In comparison, PTGER2-4 expression was mostly unexpressed or weakly expressed in urothelial and smooth cells in all regions. CONCLUSIONS: Our data indicate high levels of PTGER1 in ureters.

Potassium and ANO1/ TMEM16A chloride channel profiles distinguish atypical and typical smooth muscle cells from interstitial cells in the mouse renal pelvis.

BACKGROUND AND PURPOSE: Although atypical smooth muscle cells (SMCs) in the proximal renal pelvis are thought to generate the pacemaker signals that drive pyeloureteric peristalsis, their location and electrical properties remain obscure. EXPERIMENTAL APPROACH: Standard patch clamp, intracellular microelectrode and immunohistochemistry techniques were used. To unequivocally identify SMCs, transgenic mice with enhanced yellow fluorescent protein (eYFP) expressed in cells containing α-smooth muscle actin (α-SMA) were sometimes used. KEY RESULTS: Atypical SMCs were distinguished from typical SMCs by the absence of both a transient 4-aminopyridine-sensitive K(+) current (I(KA) ) and spontaneous transient outward currents (STOCs) upon the opening of large-conductance Ca(2+) -activated K(+) (BK) channels. Many typical SMCs displayed a slowly activating, slowly decaying Cl(-) current blocked by niflumic acid (NFA). Immunostaining for K(V) 4.3 and ANO1/ TMEM16A Cl(-) channel subunits co-localized with α-SMA immunoreactive product predominately in the distal renal pelvis. Atypical SMCs fired spontaneous inward currents that were either selective for Cl(-) and blocked by NFA, or cation-selective and blocked by La(3+) . α-SMA(-) interstitial cells (ICs) were distinguished by the presence of a Xe991-sensitive K(V) 7 current, BK channel STOCs and Cl(-) selective, NFA-sensitive spontaneous transient inward currents (STICs). Intense ANO1/ TMEM16A and K(V) 7.5 immunostaining was present in Kit(-) α-SMA(-) ICs in the suburothelial and adventitial regions of the renal pelvis. CONCLUSIONS AND IMPLICATIONS: We conclude that K(V) 4.3(+) α-SMA(+) SMCs are typical SMCs that facilitate muscle wall contraction, that ANO1/ TMEM16A and K(V) 7.5 immunoreactivity may be selective markers of Kit(-) ICs and that atypical SMCs which discharge spontaneous inward currents are the pelviureteric pacemakers.

Identification of telocytes in the upper lamina propria of the human urinary tract.

The upper lamina propria (ULP) area of interstitial cells (IC) has been studied extensively in bladder, but is rather unexplored in the rest of the urinary tract. This cell layer is intriguing because of the localization directly underneath the urothelium, the intercellular contacts and the close relationship with nerve endings and capillaries. In this study, we examine the ULP layer of IC in human renal pelvis, ureter and urethra, and we make a comparison with ULP IC in bladder. Tissue was obtained from normal areas in nephrectomy, cystectomy and prostatectomy specimens, and processed for morphology, immunohistochemistry and electron microscopy. A morphological and immunohistochemical phenotype for the ULP IC was assessed and region-dependent differences were looked for. The ULP IC in renal pelvis, ureter and urethra had a similar ultrastructural phenotype, which differed somehow from that of bladder IC, that is, thinner and longer cytoplasmic processes, no peripheral actin filaments and presence of dense core granules and microtubules. Together with their immunohistochemical profile, these features are most compatible with the phenotype of telocytes, a recently discovered group of stromal cells. Based on their global ultrastructural and immunohistochemical phenotype, ULP IC in human bladder should also be classified as telocytes. The most striking immunohistochemical finding was the variable expression of oestrogen receptor (ER) and progesterone receptor (PR). The functional relevance of ULP telocytes in the urinary tract remains to be elucidated, and ER and PR might therefore be promising pharmacological research targets.

Interstitial cells of Cajal in the urinary tract.

The study of novel interstitial cells in the tissues of the urinary tract has defined advances in the field in the last decade. These intriguing cells belong to the same family as the better known interstitial cells of Cajal (ICC) of the gastrointestinal tract, and their discovery has been interpreted to suggest that pacemaker cells may be present in the urinary tract, driving the spontaneous or myogenic activity of the neighboring smooth muscle. This scenario may be true for the urethra where ICC have been described as "loose pacemakers" providing multiple, random inputs to modulate urethral smooth muscle activity. However, there is a paucity of direct evidence available to support this hypothesis in the bladder (where the smooth muscle cells are spontaneously active) or the renal pelvis (where atypical smooth muscle cells are the pacemakers), and it now seems more likely that urinary tract ICC act as modulators of smooth muscle activity.Interestingly, the literature suggests that the role of urinary tract ICC may be more apparent in pathophysiological conditions such as the overactive bladder. Several reports have indicated that the numbers of ICC present in overactive bladder tissues are greater than those from normal tissues; moreover, the contractility of tissues from overactive bladders in vitro appears to be more sensitive to the Kit antagonist, glivec, than those from normal bladder. Future research on urinary tract ICC in the short to medium term is likely to be dynamic and exciting and will lead to increasing our understanding of the roles of these cells in both normal and dysfunctional bladder.

Distinct effects of CGRP on typical and atypical smooth muscle cells involved in generating spontaneous contractions in the mouse renal pelvis.

BACKGROUND AND PURPOSE: We investigated the cellular mechanisms underlying spontaneous contractions in the mouse renal pelvis, regulated by calcitonin gene-related peptide (CGRP). EXPERIMENTAL APPROACH: Spontaneous contractions, action potentials and Ca2+ transients in typical and atypical smooth muscle cells (TSMCs and ATSMCs) within the renal pelvis wall were recorded separately using tension and intracellular microelectrode recording techniques and Fluo-4 Ca2+ imaging. Immunohistochemical and electron microscopic studies were also carried out. KEY RESULTS: Bundles of CGRP containing transient receptor potential cation channel, subfamily V, member 1-positive sensory nerves were situated near both TSMCs and ATSMCs. Nerve stimulation reduced the frequency but augmented the amplitude and duration of spontaneous phasic contractions, action potentials and Ca2+ transients in TSMCs. CGRP and agents increasing internal cyclic adenosine monophosphate (cAMP) mimicked the nerve-mediated modulation of TSMC activity and suppressed ATSMCs Ca2+ transients. Membrane hyperpolarization induced by CGRP or cAMP stimulators was blocked by glibenclamide, while their negative chronotropic effects were less affected. Glibenclamide enhanced TSMC Ca2+ transients but inhibited ATSMC Ca2+ transients, while both 5-hydroxydecanoate and diazoxide, a blocker and opener of mitochondrial ATP-sensitive K+ channels, respectively, reduced the Ca2+ transient frequency in both TSMCs and ATSMCs. Inhibition of mitochondrial function blocked ATSMCs Ca2+ transients and inhibited spontaneous excitation of TSMCs. CONCLUSIONS AND IMPLICATIONS: The negative chronotropic effects of CGRP result primarily from suppression of ATSMC Ca2+ transients rather than opening of plasmalemmal ATP-sensitive K+ channels in TSMCs. The positive inotropic effects of CGRP may derive from activation of TSMC L-type Ca2+ channels. Mitochondrial Ca2+ handling in ATSMCs also plays a critical role in generating Ca2+ transients.

[Localization and functions of c-kit positive cells in the urinary tract]. / Rozmieszczenie i funkcje komórek cajala w drogach moczowych.

Interstitial cells of Cajal (ICCs) play an important role in the regulation of gut motility as they are responsible for the slow wave activity of smooth muscle. There is strong evidence that several subpopulations of ICC are present in the wall of the urinary tract. This review presents the currently available literature on the localization and proposed functions of interstitial cells of Cajal (ICC) in the urinary tract.

Spontaneous electrical and Ca2+ signals in typical and atypical smooth muscle cells and interstitial cell of Cajal-like cells of mouse renal pelvis.

Electrical rhythmicity in the renal pelvis provides the fundamental drive for the peristaltic contractions that propel urine from the kidney to bladder for storage until micturition. Although atypical smooth muscles (ASMCs) within the most proximal regions of the renal pelvis have long been implicated as the pacemaker cells, the presence of a sparsely distributed population of rhythmically active Kit-positive interstitial cells of Cajal-like cells (ICC-LCs) have confounded our understanding of pelviureteric peristalsis. We have recorded the electrical activity and separately visualized changes in intracellular Ca(2+) concentration in typical smooth muscle cells (TSMCs), ASMCs and ICC-LCs using intracellular microelectrodes and a fluorescent Ca(2+) indicator, fluo-4. Nifedipine (1-10 microm)-sensitive driven action potentials and Ca(2+) waves (frequency 6-15 min(-1)) propagated through the TSMC layer at a velocity of 1-2 mm s(-1). High frequency (10-40 min(-1)) Ca(2+) transients and spontaneous transient depolarizations (STDs) were recorded in ASMCs in the absence or presence of 1 microm nifedipine. ICC-LCs displayed low frequency (1-3 min(-1)) Ca(2+) transients which we speculated arose from cells that displayed action potentials with long plateaus (2-5 s). Neither electrical activity propagated over distances > 50 microm. In 1 microm nifedipine, ASMCs or ICC-LCs separated by < 30 microm displayed some synchronicity in their Ca(2+) transient discharge suggesting that they may well be acting as 'point sources' of excitation to the TSMC layer. We speculate that ASMCs act as the primary pacemaker in the renal pelvis while ICC-LCs play a supportive role, but can take over pacemaking in the absence of the proximal pacemaker drive.

Electrical characterization of interstitial cells of Cajal-like cells and smooth muscle cells isolated from the mouse ureteropelvic junction.

PURPOSE: We characterized membrane currents in smooth muscle cells and interstitial cells freshly isolated from the mouse ureteropelvic junction. MATERIALS AND METHODS: Interstitial cells of Cajal-like cells were identified using c-Kit antibodies and fresh whole mount preparations of ureteropelvic junction. Whole cell and ion channel currents were recorded in collagenase dispersed single cells using standard patch clamp techniques. RESULTS: Membrane depolarization of single smooth muscle cells evoked a complex K(+) selective outward current consisting of a rapidly activating 4-aminopyridine sensitive transient outward current, followed by a more slowly developing outward current that was decreased by blockers of large conductance Ca(2+) activated K(+) channels. In contrast, membrane depolarization of stellate interstitial cells evoked a slowly developing outward current that did not arise from the opening of transient outward current or large conductance Ca(2+) activated K(+) channels. Under current clamp interstitial cells showed random fluctuations of membrane potential and occasional large, long lasting depolarizations. Under voltage clamp interstitial cells showed high frequency spontaneous transient inward currents that often occurred in bursts to sum and produce long lasting large inward currents. Large inward currents had reversal potentials of almost -10 mV if the Nernst potential for Cl(-) was set at -4 or -78 mV. They were little affected by the Cl(-) channel blockers DIDS (4,4'-diisothiocyanostilbene-2,2'-disulphonic acid) and niflumic acid. CONCLUSIONS: We speculate that single stellate interstitial cells are c-Kit positive interstitial cells of Cajal-like cells viewed in intact tissue, which generate cationic selective spontaneous transient inward currents that sum to form large inward currents. In the absence of a proximal pacemaker drive these interstitial cells of Cajal-like cells could well trigger contraction in neighboring smooth muscle cell bundles in the ureteropelvic junction.

Collagen changes in the ureteropelvic junction after failed antegrade endopyelotomy.

PURPOSE: We evaluated the collagen content and differentiation of the ureteropelvic junction (UPJ) of patients who underwent Anderson-Hynes dismembered pyeloplasty after failure of antegrade endopyelotomy. MATERIALS AND METHODS: A total of 12 UPJ obstructions were examined more than 12 months after endopyelotomy with both histochemical staining to analyze total collagen content and immunohistochemical staining to analyze collagen types I and III. The specimens were compared with 12 primary UPJ obstructions and 6 normal UPJs. Statistical analysis was performed using Fisher's test and Wilcoxon matched-pairs signed-rank test. RESULTS: Immunohistochemical staining revealed that collagen type I was located in the interfascicular space and collagen type III in the intrafascicular space in all UPJs. We found more collagen in obstructed than in normal UPJs. Collagen type III was more abundant in secondary than in primary UPJ obstructions (P < 0.01). In obstruction after endopyelotomy, the staining intensity of collagen type III was greater than the intensity of collagen type I (P < 0.01). CONCLUSION: Our results suggest that the success of antegrade endopyelotomy was impaired by an inflammatory process. This condition determined a shift of collagen differentiation toward type III, which is more fibrous than type I.

[The uteropelvic junction in children: from the clinical problems to the morphogenetic approach]. / La jonction pyélourétérale chez l'enfant: de la problématique clinique à l'approche morphogénique.

The responsibility of the uteropelvic junction (UPJ) syndrome or abnormalities for renal affections and also for high obstructive uropathy is well-known. But, controversies still remain about the anatomic approach of this clinical feature. Our purpose is to elucidate the developmental anatomy of UPJ and eventually to set the steps of the anatomic approach of the UPJ abnormalities. This study also leads to a better understanding of the mechanism of the intrinsic ureteropelvic junction obstructions. A total number of 122 post-mortem specimens with ages ranging from 1 day to 30 months in both sexes underwent formalin treatment for histological investigation. We performed both transverse and longitudinal sections. Hematein-eosin-safran and Masson's trichrome staining were used. Histological examination revealed that myoarchitecture of UPJ set increasingly up. Circular muscle fibers were first to put in. They had an initial arrangement as a ring in neonates and infants. We conclude that circular layer appears first and sooner than others. On the other hand, coincidence in time between ages of our specimens and ages of patients sufferning from UPJ syndrome leads to further investigations to determine the implication of ring-shaped circular layer in intrinsic ureteropelvic junction obstruction.

Identification of genes involved in human urothelial cell-matrix interactions: implications for the progression pathways of malignant urothelium.

Interactions between epithelial cells and the extracellular matrix are central to tissue homeostasis and have a dynamic role in tissue remodeling and repair. Regulation of these pathways is balanced by positive and negative feedback elements, many of which have been implicated in the pathways of malignant progression. We have used differential display to identify genes that are up-regulated in normal human urothelial cells in response to exposure to extracellular matrix proteins (Matrigel) in vitro. This approach has identified genes that have key roles in cell-cell and cell-matrix interactions and that have been implicated in the progression of carcinomas of urothelial or other epithelial cell origins. One confirmed but unknown differentially expressed sequence was used to isolate a full-length gene, MIG-C4, from a human urothelial cDNA library. This gene was found to encode a novel urokinase plasminogen-activator receptor-like member of the Ly-6 family of glycosyl-phosphatidylinositol-anchored glycoproteins, and was identified as the human homologue of the rat metastasis-associated C4.4A gene. By in situ hybridization, MIG-C4 was expressed variably in normal urothelium and intensely in the tumor component of some noninvasive superficial lesions and in invasive and metastatic urothelial cancers. Thus, our approach has identified previously nonimplicated gene products involved in normal urothelium-matrix interactions that could be tumor-invasion or suppressor-gene targets in the development of invasive and metastatic tumor phenotypes.

Catheterized urine cytology of mucinous carcinoma arising in the renal pelvis. A case report.

BACKGROUND: Primary mucinous carcinoma of the renal pelvis is a rare tumor; therefore, criteria for cytologic diagnosis of this tumor have not been established. CASE: An 81-year-old woman suffered from macrohematuria for six months and was found to have a tumor in the right kidney by radiographic examination. Catheterized urine obtained from the right renal ureter was viscous and contained spherical clusters of cells with occasionally vacuolated, lacy and basophilic cytoplasm. In the small to medium-sized nuclei, chromatin was coarse and granular, and the nuclear membrane was thin and nearly smooth. Large nucleoli were evident in some of the nuclei. These findings were consistent with adenocarcinoma possibly of mucinous type. CONCLUSION: Preoperative diagnosis of mucinous carcinoma is possible by cytologic findings of catheterized urine together with clinical data.

Properties of spontaneous electrical activity in smooth muscle of the guinea-pig renal pelvis.

In the guinea-pig renal pelvis, most smooth muscle cells examined (>90%), using a conventional microelectrode, had a resting membrane potential of about -50 mV and produced spontaneous action potentials with initial fast spikes and following plateau potentials. The remainder (<10%) had a resting membrane potential of about -40 mV and produced periodical depolarization with slow rising and falling phases. Experiments were carried out to investigate the properties of spontaneous action potentials. The potentials were abolished by nifedipine, suggesting a possible contribution of voltage-gated Ca(2+) channels to the generation of these potentials. Niflumic acid and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), inhibitors of Ca(2+)-activated Cl(-) channels, showed different effects on the spontaneous action potentials, and the former but not the latter inhibited the activities, raised the question of an involvement of Cl(-) channels in the generation of these activities. Depleting internal Ca(2+) stores directly with caffeine or indirectly by inhibiting Ca(2+)-ATPase at the internal membrane with cyclopiazonic acid (CPA) prevented the generation of spontaneous activity. Chelating intracellular Ca(2+) by 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) increased the amplitude of the spike component of spontaneous activity. Indomethacin inhibited the spontaneous activity, whereas prostaglandin F(2 alpha) enhanced it. The results indicate that in smooth muscle of the renal pelvis, the generation of spontaneous activity is causally related to the activation of voltage-gated Ca(2+) channels through which the influx of Ca(2+) may trigger the release of Ca(2+) from the internal stores to activate a set of ion channels at the membrane. Endogenous prostaglandins may be involved in the initiation of spontaneous activity.

Ureteropelvic junction: A study of its anatomical structure and function. Ureteropelvic junction sphincter?

PURPOSE: To study the anatomy of the normal ureteropelvic junction (UPJ) and investigate its pressure response to distension, aiming at elucidation of its function in the light of its anatomical structure. METHOD: The UPJ of 25 cadaveric specimens (15 male, 10 female; 15 adults, mean age 33.6 +/- 8.4 years; 10 fully mature neonatal deaths) was studied morphologically and microscopically after staining with hematoxylin and eosin and Masson's trichrome. Furthermore, the length of the UPJ as well as the UPJ pressure response to UPJ distension were assessed in 13 subjects (8 men, 5 women, age 48.8 +/- 10.3 years). The response of the anesthetized UPJ to distension was reported in 7/13 subjects and of the saline-injected UPJ in the remaining 6/13. The UPJ had been anesthetized by injecting 1% xylocaine into its wall. RESULTS: Grossly, there were no features characteristic of the UPJ externally, although internally the mucosa was thrown into folds forming a 'mucosal rosette'. Microscopic examination showed the muscle fibers to be arranged in two well-formed layers: circular and longitudinal. Mucosal folding and structured muscle fiber arrangement were lacking in the adjacent renal pelvic and ureteral walls. The mean UPJ length in adults as measured manometrically by the pull-through technique was 6.9 +/- 1.5 mm. UPJ distension led to an elevated UPJ pressure; the latter increased with increase of the volume of distension. There was no UPJ pressure response to distension of the UPJ locally anesthetized by injecting xylocaine into its tissue, but there was response when saline was injected into the tissue of the UPJ. CONCLUSION: The UPJ might be identifiable by the presence of the mucosal rosette. The reaction of the UPJ to distension probably indicates that the UPJ possesses a motile activity. This, as well as the presence of a structured muscle coat at the UPJ would suggest the presence of a 'sphincter' at the UPJ.

Effects of short-chain fatty acids on primary urothelial cells in culture: implications for intravesical use in enterocystoplasties.

The presence of inflammatory changes and mucopus production in an enterocystoplasty may be similar to the condition of diversion colitis and starvation diarrhea caused by a lack of luminal short-chain fatty acids (SCFAs). We postulate a therapeutic role for intravesical SCFA. Because this treatment will also contact the urothelium, we have assessed the effect on cellular proliferation by utilizing primary urothelial cells in culture. Primary urothelial cells were grown from biopsy samples of normal urothelium obtained intraoperatively. A cocktail of SCFA used in the treatment of diversion colitis was incubated with these cells for time intervals ranging from 30 minutes to 72 hours at drug concentrations ranging from 0.04 to 20 mmol/L butyrate equivalent (BE). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to measure the residual viable biomass to assess growth inhibition. These experiments were repeated on cells grown on matrigel substrate. The human urothelial cancer line RT112 was likewise exposed to SCFAs to assess selectivity between primary and transformed cells. Primary urothelial cells in culture undergo growth inhibition when exposed to SCFAs. The concentration of SCFAs required to reduce the general biomass by 50% or more (IC> or =50) was 20 mmol/L BE when exposure was for 2 hours or less. When drug exposure was prolonged for 72 hours, the IC> or =50 was 2.5 mmol/L BE. Cells grown on matrigel had their growth similarly inhibited. The IC > or = 50 for the RT112 cell line was 2.5 mmol/L BE after 72 hours of drug incubation. Primary urothelial cells in culture undergo a time- and dose-dependent growth inhibition when exposed to SCFAs. This inhibition is particularly apparent at the higher doses similar to those in use in clinical practice. Cells grown on a matrigel substrate suffer growth attenuation similar to that affecting cells grown on polystyrene plates. In vivo assessment in a rodent intravesical model is advisable before considering instillations in patients.