Evaluation of ureteric contraction: a comparison among ring, spiral-cut and longitudinal segments

Prognostic Significance of Substance P and Neurokinin-1 Receptor in Bladder Cancer

Background

Bladder cancer is one of the most common genitourinary cancers with significant mortality. Finding reliable tumor markers and potential drug targets can improve early diagnosis, prognosis, and more effective therapeutic protocols. Previous studies have reported the involvement of the substance P (SP)/neurokinin-1 receptor (NK-1R) system in cancers. The potential prognostic role and the interaction of SP and NK-1R in bladder tumor are yet to be elucidated.

Methods

Serum samples from 22 primarily diagnosed patients with bladder cancer as well as 22 healthy controls were examined for SP level using ELISA method. Tissue distribution of NK-1R in tumor samples and their adjacent normal tissues was evaluated through immunohistochemistry.

Results

Serum SP levels in patients with bladder cancer were higher than the healthy group (p< 0.001) and had a significant correlation with NK-1R staining intensity (p< 0.001), percentage of stained cells (p< 0.001), and NK-1R tissue distribution. Also, the immunoreactivity of NK-1R in cancer samples increased significantly without correlation with tumor characteristics. However, no significant association was found between SP and NK-1R levels with clinical characteristics including tumor size (p= 0.33), tumor stage (p= 0.29), grade (p= 0.93), NK-1R staining intensity (p= 0.53), and percentage of stained cells (p= 0.32).

Discussion

According to our findings, despite the lack of association between SP and NK-1R with clinical characteristics of bladder cancer, their serum levels were higher in patients with bladder cancer. Further studies are needed to confirm the potential prognostic role of SP and NK-1R in bladder cancer.

Effect of Flos carthami Extract and α 1-Adrenergic Antagonists on the Porcine Proximal Ureteral Peristalsis

Traditional Chinese medicine (TCM) has been proposed to prevent urolithiasis. In China, Flos carthami (FC, also known as Carthamus tinctorius) (Safflower; Chinese name: Hong Hua/紅花) has been used to treat urological diseases for centuries. We previously performed a screening and confirmed the in vivo antilithic effect of FC extract. Here, ex vivo organ bath experiment was further performed to study the effect of FC extract on the inhibition of phenylepinephrine (PE) (10⁻⁴ and 10⁻³ M) ureteral peristalsis of porcine ureters with several α₁-adrenergic antagonists (doxazosin, tamsulosin, and terazosin) as experimental controls. The results showed that doxazosin, tamsulosin, and terazosin dose (approximately 4.5 × 10⁻⁶ − 4.5 × 10⁻¹  μg/mL) dependently inhibited both 10⁻⁴ and 10⁻³ M PE-induced ureteral peristalsis. FC extract achieved 6.2% ± 10.1%, 21.8% ± 6.8%, and 24.0% ± 5.6% inhibitions of 10⁻⁴ M PE-induced peristalsis at doses of 5 × 10³, 1 × 10⁴, and 2 × 10⁴  μg/mL, respectively, since FC extract was unable to completely inhibit PE-induced ureteral peristalsis, suggesting the antilithic effect of FC extract is related to mechanisms other than modulation of ureteral peristalsis.

Effects of a non-selective COX inhibitor and selective COX-2 inhibitors on contractility of human and porcine ureters in vitro and in vivo

BACKGROUND AND PURPOSE

Anti-inflammatory drugs are used in the treatment of acute renal colic. The aim of this study was to investigate the effects of selective COX-2 inhibitors and the non-selective COX inhibitor diclofenac on contractility of human and porcine ureters in vitro and in vivo, respectively. COX-1 and COX-2 receptors were identified in human ureter and kidney.

EXPERIMENTAL APPROACH

Human ureter samples were used alongside an in vivo pig model with or without partial ureteral obstruction. COX-1 and COX-2 receptors were located in human ureters by immunohistochemistry.

KEY RESULTS

Diclofenac and valdecoxib significantly decreased the amplitude of electrically-stimulated contractions in human ureters in vitro, the maximal effect (Vmax) being 120 and 14%, respectively. Valdecoxib was more potent in proximal specimens of human ureter (EC50=7.3 x 10(-11) M) than in distal specimens (EC50=7.4 x 10(-10) M), and the Vmax was more marked in distal specimens (22.5%) than in proximal specimens (8.0%) in vitro. In the in vivo pig model, parecoxib, when compared to the effect of its solvent, significantly decreased the maximal amplitude of contractions (Amax) in non-obstructed ureters but not in obstructed ureters. Diclofenac had no effect on spontaneous contractions of porcine ureter in vivo. COX-1 and COX-2 receptors were found to be expressed in proximal and distal human ureter and in tubulus epithelia of the kidney.

CONCLUSIONS AND IMPLICATIONS

Selective COX-2 inhibitors decrease the contractility of non-obstructed, but not obstructed, ureters of the pig in vivo, but have a minimal effect on electrically-induced contractions of human ureters in vitro.

Doxazosin relaxes ureteral smooth muscle and inhibits epinephrine-induced ureteral contractility in vitro

OBJECTIVES

Although recent evidence has supported increased ureteral stone passage with selective alpha(1)-adrenergic receptor antagonists, no mechanistic study evaluating ureteral relaxation by alpha(1) antagonism has been reported to date. We evaluated whether the alpha-blocker doxazosin reduces spontaneous, and inhibits alpha(1)-agonist-induced ureteral contractility. Additionally, alpha-receptor subtypes in normal and obstructed human ureter were analyzed.

METHODS

We exposed porcine ureters in organ tissue baths with 0.1, 1.0, or 10 microM doxazosin and recorded the tension for 90 minutes. After the initial treatment, a concentration-response curve of epinephrine or phenylephrine (1 nM to 10 microM) was generated. The experiment was repeated with the proximal, mid-, and distal ureter. The relative expression of the alpha 1A, 1B, and 1D receptor subtypes in normal and obstructed human ureters was analyzed using immunoblotting.

RESULTS

Doxazosin reduced the spontaneous ureteral contractility rates in a concentration-dependent fashion by 23% to 34%. A more pronounced relaxation effect by doxazosin was evident when epinephrine was introduced to the tissues. In 1 and 10-microM doxazosin-pretreated tissues, epinephrine caused 89% and 100% relaxation, respectively. Phenylephrine-induced contractions were antagonized by doxazosin but not reversed to any relaxant function. No differential expression of alpha(1)-receptor subtypes was identified in the obstructed versus normal ureters.

CONCLUSIONS

The results of our study have shown that alpha(1)-receptor blockade decreases ureteral contractility and inverses the effect of epinephrine, providing even greater relaxation. We hypothesize that alpha receptor blockade might relax the ureter and induce stone passage by way of epinephrine activation of beta receptors. Additional studies should be performed to validate this hypothesis and to compare various alpha(1)-receptor subtype antagonists.

Bladder inflammatory transcriptome in response to tachykinins: neurokinin 1 receptor-dependent genes and transcription regulatory elements

BACKGROUND

Tachykinins (TK), such as substance P, and their neurokinin receptors which are ubiquitously expressed in the human urinary tract, represent an endogenous system regulating bladder inflammatory, immune responses, and visceral hypersensitivity. Increasing evidence correlates alterations in the TK system with urinary tract diseases such as neurogenic bladders, outflow obstruction, idiopathic detrusor instability, and interstitial cystitis. However, despite promising effects in animal models, there seems to be no published clinical study showing that NK-receptor antagonists are an effective treatment of pain in general or urinary tract disorders, such as detrusor overactivity. In order to search for therapeutic targets that could block the tachykinin system, we set forth to determine the regulatory network downstream of NK1 receptor activation. First, NK1R-dependent transcripts were determined and used to query known databases for their respective transcription regulatory elements (TREs).

METHODS

An expression analysis was performed using urinary bladders isolated from sensitized wild type (WT) and NK1R-/- mice that were stimulated with saline, LPS, or antigen to provoke inflammation. Based on cDNA array results, NK1R-dependent genes were selected. PAINT software was used to query TRANSFAC database and to retrieve upstream TREs that were confirmed by electrophoretic mobility shift assays.

RESULTS

The regulatory network of TREs driving NK1R-dependent genes presented cRel in a central position driving 22% of all genes, followed by AP-1, NF-kappaB, v-Myb, CRE-BP1/c-Jun, USF, Pax-6, Efr-1, Egr-3, and AREB6. A comparison between NK1R-dependent and NK1R-independent genes revealed Nkx-2.5 as a unique discriminator. In the presence of NK1R, Nkx2-5 _01 was significantly correlated with 36 transcripts which included several candidates for mediating bladder development (FGF) and inflammation (PAR-3, IL-1R, IL-6, alpha-NGF, TSP2). In the absence of NK1R, the matrix Nkx2-5_02 had a predominant participation driving 8 transcripts, which includes those involved in cancer (EYA1, Trail, HSF1, and ELK-1), smooth-to-skeletal muscle trans-differentiation, and Z01, a tight-junction protein, expression. Electrophoretic mobility shift assays confirmed that, in the mouse urinary bladder, activation of NK1R by substance P (SP) induces both NKx-2.5 and NF-kappaB translocations.

CONCLUSION

This is the first report describing a role for Nkx2.5 in the urinary tract. As Nkx2.5 is the unique discriminator of NK1R-modulated inflammation, it can be imagined that in the near future, new based therapies selective for controlling Nkx2.5 activity in the urinary tract may be used in the treatment in a number of bladder disorders.

A comparative in vitro study to determine the beneficial effect of calcium-channel and alpha(1)-adrenoceptor antagonism on human ureteric activity

OBJECTIVE

To compare the in vitro human ureteric muscle response to calcium-channel and alpha-adrenoceptor antagonists, to determine the promoting factor for stone passage. Clinical trials suggest that stone passage in renal colic can be promoted by ureteric relaxation using these agents, however nonsteroidal anti-inflammatory drugs appear to reduce ureteric activity in vitro but do not promote stone passage when used in clinical trials.

MATERIALS AND METHODS

Human ureteric muscle strips were used to record the effect that each drug had on muscle tone in vitro. The ureter was obtained at open nephrectomy or cystectomy. Potassium-enriched Krebs' solution was used to evoke maximal muscle tone, followed by adding each drug in increasing concentrations to determine the percentage reduction in tone. The drugs used to represent each group were nifedipine, 5-methylurapidil (5-MU) and diclofenac. In all, 201 ureteric strips were obtained from 39 patients.

RESULTS

At all drug concentrations, the in vitro relaxant effect of nifedipine and 5-MU was greater than that of diclofenac. At 10(-5) M the median reduction in proximal and distal ureteric tone to diclofenac, nifedipine and 5-MU were 18%, 5% and 47%, vs 57%, 33% and 65%, respectively.

CONCLUSION

Nifedipine and 5-MU produced greater ureteric relaxation in vitro than diclofenac; they predominantly relax distal ureter. This suggests that a reduction in ureteric muscle tone, as opposed to complete ablation of activity, might be the promoting factor for stone passage.

Third Prize:Prostaglandin E2-3 Receptor Is Involved in Ureteral Contractility in Obstruction

BACKGROUND AND PURPOSE

We previously found that prostaglandin (PG) E2 contracts acutely obstructed ureters while relaxing normal ureters. This study investigated the procontractile effects of the PG EP3 receptor in PGE(2)-mediated contractility in obstructed and normal porcine ureters.

MATERIALS AND METHODS

We created unilateral ureteral obstruction laparoscopically using titanium clips in farm pigs; the contralateral ureters were dissected as sham controls. Ureters were harvested 48 hours post-obstruction, cut into 5-mm segments, and suspended in water-jacketed tissue baths in Krebs buffer. Tissues were equilibrated for 1 hour, and spontaneous contractile rates were recorded. After 2 hours of incubation in Krebs (controls) or pertussis toxin (G(alpha)i signaling-protein inhibitor [EP-3 blockade]) 500 ng/mL, a concentration- response curve (10(-9) M-10(-5) M) to PGE(2), PGF(2), sulprostone (EP 3 agonist), or 0.01% ethanol (vehicle) was created (N = 4).

RESULTS

In the normal ureters, PGE(2) relaxed both pertussis toxin-treated and control tissues. In obstructed segments, PGE(2) increased contractions by 60%; this was reversed by pertussis toxin to a 67% reduction in contractile rate. In both obstructed and contralateral segments, sulprostone induced contractility in the controls; this was attenuated by pertussis toxin. The PGF(2) produced a contractile effect in both the controls and the pertussis toxin-treated segments, demonstrating the selectivity of pertussis toxin for EP3 receptors.

CONCLUSION

Our data indicate that the EP3 receptor is involved in hypercontractility during ureteral obstruction. However, it may not be the sole factor behind the condition-dependent effect of PGE(2).

Obstruction alters the effect of prostaglandin E2 on ureteral contractility

BACKGROUND AND PURPOSE

Although our understanding of ureteral physiology during acute obstruction remains limited, we believe that prostanoids (prostaglandins [PGs], thromboxanes, prostacyclins) play a major role in modulation of ureteral contractility and that inhibition of prostanoid synthesis causes substantial reduction in in-vitro and in-vivo ureteral contractility rates. The purpose of this study was to determine the in-vitro effects of PGE2 on chronically obstructed human and acutely obstructed porcine ureters.

MATERIALS AND METHODS

Female pigs underwent unilateral laparoscopic ureteral obstruction. Following 1, 2, 6, 24, and 48 hours of obstruction (n = 3 at all points), animals were euthanized, and obstructed, contralateral nonobstructed, and normal (from unobstructed pigs) ureters were harvested. Chronically obstructed human ureter was obtained from subjects who underwent nephrectomy to remove nonfunctioning kidneys. Normal human ureter was obtained from the discarded portion of excess distal ureter in patients undergoing elective donor nephrectomy. Rings 4 to 5 mm long were suspended in aerated Krebs buffer, and their spontaneous contractions and contraction in response to various concentrations of PGE2 were recorded.

RESULTS

Prostaglandin E2 increased contractility in chronically obstructed human ureters. In acutely obstructed porcine ureteral segments, low concentrations of PGE2 inhibited ureteral contractility in a dose-dependent fashion, similar to controls. At higher concentrations of PGE2, contractility was increased. This increase was more pronounced with longer intervals of obstruction in a time-dependent manner.

CONCLUSION

Prostaglandin E2 increased contractility in obstructed ureters while relaxing normal and nonobstructed ureters. The response to PGE2 was accentuated by a longer duration of obstruction. Prostaglandin E2 may be a unique target for pharmacologic modulation in the treatment of symptoms associated with acute urinary obstruction.

Involvement of Rho-kinase in the contractile mechanism of human ureteral smooth muscle

AIM

Even though many agents have been implicated as modulators of ureteral contractile activity, the exact mechanisms that control human ureteral smooth muscle contractility have yet to be clearly defined. Recently, Rho-kinase has been reported to be involved in the contractile mechanism of smooth muscles in various organs. In the present study, we sought to investigate whether or not Rho-kinase is expressed in the human ureteral smooth muscle, and to study its role regarding human ureteral smooth muscle contractility.

METHODS

Ureteral samples were obtained from human adult subjects undergoing radical nephrectomy. Immunohistochemistry and Western blotting were performed to determine the presence of Rho-kinase in human ureter. Functional studies were performed with human ureteral strips suspended in organ bath, and the effects of Y-27632, a specific inhibitor of Rho-kinase, on baseline tensions, spontaneous contractions, and electrical field stimulation (EFS)-induced contractions were analyzed.

RESULTS

The results of immunohistochemistry and immunoblotting study indicated that Rho-kinase is present in human ureteral smooth muscle. In functional analysis, Y-27632 was shown to decrease the baseline tension. And, both spontaneous and EFS-induced contractile responses of human ureteral strips were attenuated by Y-27632 in dose-dependent manners.

CONCLUSIONS

For the first time, the results of the present study indicate that Rho-kinase is present in human ureteral smooth muscle and may play an important role in the intricate mechanism of human ureteral contractility and tone.

Celecoxib inhibits ureteral contractility and prostanoid release

OBJECTIVES

To evaluate the efficacy and potency of clinically available celecoxib for inhibition of ureteral contractility and prostanoid release. We have previously reported that the selective cyclooxygenase (COX)-2 inhibitor NS-398 inhibits ureteral contractility.

METHODS

We evaluated the release of prostaglandin (PG) E2, F2alpha, D2, thromboxane B2 (a thromboxane2 metabolite), and 6-keto-PGF1alpha (a prostacyclin metabolite) by gas chromatography-mass spectrometry from porcine ureters in the presence and absence of tumor necrosis factor-alpha (TNF-alpha), a putative cyclooxygenase (COX)-2 inducer. PGE2 and PGF2alpha were the prostanoids released in greatest quantity in response to TNF-alpha. We subsequently measured spontaneous contractility and prostanoid release in porcine ureters treated with 0.1, 1.0, or 10 microM concentrations of indomethacin (nonselective COX inhibitor), NS-398, celecoxib, or 0.1% dimethyl sulfoxide (vehicle) for 2 hours. Ureteral contractility and prostanoid release were measured every 15 minutes after the addition of the various compounds. We also treated ureters with 10 ng/mL TNF-alpha and all three COX inhibitors or dimethyl sulfoxide for 2 and 4 hours and measured the PGE2 and PGF2alpha release.

RESULTS

Celecoxib, indomethacin, and NS-398 inhibited ureteral contractility and prostanoid release with similar efficacy and potency. All three compounds also reduced TNF-alpha-induced prostanoid release to control levels at concentrations as low as 0.1 microM.

CONCLUSIONS

Our data have indicated that celecoxib and indomethacin inhibit PG release by the ureter to a similar degree, even in the presence of COX-2 induction. Animal experiments and clinical trials evaluating the safety and efficacy of celecoxib for the treatment of symptomatic ureteral obstruction are warranted.

Distribution of neuropeptides, histamine content, and inflammatory cells in the ureter

OBJECTIVES

To determine the anatomic distribution of select neuropeptides (neurokinin A [NKA], substance P [SP], and bradykinin [BK]), of inflammatory cells (leukocytes and mast cells), and the histamine content in the normal swine ureter and compare the findings with regions of increased ureteral contractility.

METHODS

Ureters from 10 pigs were obtained and cut into eight segments, proximally to distally. A portion of each ureteral segment was suspended in Krebs buffer (37 degrees C) and attached to force displacement transducers, and spontaneous contractility was measured for 30 minutes. A second portion was assayed for histamine, NKA, SP, and BK using enzyme-linked immunosorbent assay. A third portion was fixed in 10% buffered formalin, stained with hematoxylin-eosin, and evaluated histologically.

RESULTS

Ureteral contractility was found to be highest in the most proximal and most distal regions of the ureter. Similarly, SP content was three times greater in the proximal ureter and two times greater in the distal ureter than in the midureter (P <0.05, n = 10). The total NKA and BK content were also higher in the proximal and distal ureter than in the midureter. Conversely, the histamine content was consistent throughout the ureter. Moreover, no significant difference in the distribution of inflammatory cells was identified throughout the ureter.

CONCLUSIONS

The anatomic distribution of NKA, SP, and BK in the ureter corresponded to regions of increased spontaneous ureteral contractility, more specifically the proximal and distal ureter. Neuropeptides may play a significant role in ureteral contractility and may be a target for pharmacologic mediation during obstruction and stone passage.