Noradrenaline modulates smooth muscle activity of the isolated intravesical ureter of the pig through different types of adrenoceptors

Improved stone quality of life in patients with an obstructing ureteral stone on alpha-blocker medical expulsive therapy

PURPOSE

Though controversial, alpha blockers are used widely for ureteral stone passage. However, its effects on the patient-reported Quality of life (QOL) is unknown. We compared the QoL of patients on alpha-blocker medical expulsive therapy (MET) to patients not on MET (noMET) utilizing the validated Wisconsin Stone Quality of Life (WISQOL).

METHODS

This prospective study included patients prescribed either MET or noMET after presentation with symptomatic, obstructing ureteral stones. The treatment arm was decided at the point of care by the initial treating physician and included analgesia and antiemetics. Tamsulosin (0.4 mg daily) was prescribed for the MET group. The WISQOL survey was administered at baseline, 7-, 14-, 21- and 28-days following discharge from the ED or until stone expulsion.

RESULTS

197 patients were enrolled, of which 116 (59.2%) completed questionnaires for analysis, 91 in the MET group and 25 in noMET. Average ureteral stone size was 4.7 mm (SD 1.8) and 3.1 mm (SD 1.0) for MET and noMET, respectively. Of completed surveys, 105 (90%) were completed at day 7, 67 (57.6%) at day 14, 53 (45.7%) at day 21, and 40 (34.5%) at day 28. MET was associated with improved QoL scores across all WISQOL domains compared to noMET. Stone size, age, race, sex, comorbidity score and a prior stone history were not associated with reduced QoL.

CONCLUSIONS

The use of MET was associated with improved QOL on all WISQOL metrics compared to noMET patients. Improved stone QOL may be an indication of alpha-blocker therapy in patients with ureteral stone colic.

Role of α- and β-adrenergic signaling in phenotypic targeting: significance in benign and malignant urologic disease

The urinary tract is highly innervated by autonomic nerves which are essential in urinary tract development, the production of growth factors, and the control of homeostasis. These neural signals may become dysregulated in several genitourinary (GU) disease states, both benign and malignant. Accordingly, the autonomic nervous system is a therapeutic target for several genitourinary pathologies including cancer, voiding dysfunction, and obstructing nephrolithiasis. Adrenergic receptors (adrenoceptors) are G-Protein coupled-receptors that are distributed throughout the body. The major function of α1-adrenoceptors is signaling smooth muscle contractions through GPCR and intracellular calcium influx. Pharmacologic intervention of α-and β-adrenoceptors is routinely and successfully implemented in the treatment of benign urologic illnesses, through the use of α-adrenoceptor antagonists. Furthermore, cell-based evidence recently established the antitumor effect of α1-adrenoceptor antagonists in prostate, bladder and renal tumors by reducing neovascularity and impairing growth within the tumor microenvironment via regulation of the phenotypic epithelial-mesenchymal transition (EMT). There has been a significant focus on repurposing the routinely used, Food and Drug Administration-approved α1-adrenoceptor antagonists to inhibit GU tumor growth and angiogenesis in patients with advanced prostate, bladder, and renal cancer. In this review we discuss the current evidence on (a) the signaling events of the autonomic nervous system mediated by its cognate α- and β-adrenoceptors in regulating the phenotypic landscape (EMT) of genitourinary organs; and (b) the therapeutic significance of targeting this signaling pathway in benign and malignant urologic disease. Video abstract.

Current and emerging pharmacological targets for medical expulsive therapy

The primary goals of medical expulsive therapy are to increase the rate of stone expulsion along the ureter to avoid ureteral obstruction and reduce ureteral colic and thus avoid the need for surgical and more invasive interventions. This review focussed on the findings from in vivo and in vitro animal and human studies that have investigated the pharmacological mechanisms controlling ureteral motility and their translation to current and potentially new clinically used drugs for increasing the rate of stone expulsion along the ureter. The complicated contractility profile of the ureter, which alters with age, tissue segment region, orientation and species contributes to the difficulty of interpreting studies on ureteral pharmacology, which translates to the complexity of discovering ideal drug targets for medical expulsive therapy. Nevertheless, the current drug classes clinically used for patients with stone lodgement include α₁ -adrenoceptor antagonists, calcium channel blockers and NSAIDS, whilst there are promising targets for drug development that require further clinical investigations including the phosphodiesterase type 5 enzyme, β-adrenoceptors and 5-HT receptors.

Alpha-blockers after shock wave lithotripsy for renal or ureteral stones in adults

BACKGROUND

Shock wave lithotripsy (SWL) is a widely used method to treat renal and ureteral stone. It fragments stones into smaller pieces that are then able to pass spontaneously down the ureter and into the bladder. Alpha-blockers may assist in promoting the passage of stone fragments, but their effectiveness remains uncertain.  OBJECTIVES: To assess the effects of alpha-blockers as adjuvant medical expulsive therapy plus usual care compared to placebo and usual care or usual care alone in adults undergoing shock wave lithotripsy for renal or ureteral stones.

SEARCH METHODS

We performed a comprehensive literature search of the Cochrane Library, the Cochrane Database of Systematic Reviews, MEDLINE, Embase, several clinical trial registries and grey literature for published and unpublished studies irrespective of language. The date of the most recent search was 27 February 2020.

SELECTION CRITERIA

We included randomized controlled trials of adults undergoing SWL. Participants in the intervention group had to have received an alpha-blocker as adjuvant medical expulsive therapy plus usual care. For the comparator group, we considered studies in which participants received placebo.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion/exclusion, and performed data abstraction and risk of bias assessment. We conducted meta-analysis for the identified dichotomous and continuous outcomes using RevManWeb according to Cochrane methods using a random-effects model. We judged the certainty of evidence on a per outcome basis using GRADE.

MAIN RESULTS

We included 40 studies with 4793 participants randomized to usual care and an alpha-blocker versus usual care alone. Only four studies were placebo controlled. The mean age of participants was 28.6 to 56.8 years and the mean stone size prior to SWL was 7.1 mm to 13.2 mm. The most widely used alpha-blocker was tamsulosin; others were silodosin, doxazosin, terazosin and alfuzosin.  Alpha-blockers may improve clearance of stone fragments after SWL (risk ratio (RR) 1.16, 95% confidence interval (CI) 1.09 to 1.23; I² = 78%; studies = 36; participants = 4084; low certainty evidence). Based on the stone clearance rate of 69.3% observed in the control arm, an alpha-blocker may increase stone clearance to 80.4%. This corresponds to 111 more (62 more to 159 more) participants per 1000 clearing their stone fragments. Alpha-blockers may reduce the need for auxiliary treatments after SWL (RR 0.67, 95% CI 0.45 to 1.00; I² = 16%; studies = 12; participants = 1251; low certainty evidence), but also includes the possibility of no effect. Based on a rate of auxiliary treatments in the usual care arm of 9.7%, alpha-blockers may reduce the rate to 6.5%. This corresponds 32 fewer (53 fewer to 0 fewer) participants per 1000 undergoing auxiliary treatments. Alpha-blockers may reduce major adverse events (RR 0.60, 95% CI 0.46 to 0.80; I² = 0%; studies = 7; participants = 747; low certainty evidence). Major adverse events occurred in 25.8% of participants in the usual care group; alpha-blockers would reduce this to 15.5%. This corresponds to 103 fewer (139 fewer to 52 fewer) major adverse events per 1000 with alpha-blocker treatment. None of the reported major adverse events appeared drug-related; most were emergency room visits or rehospitalizations. Alpha-blockers may reduce stone clearance time in days (mean difference (MD) -3.74, 95% CI -5.25 to -2.23; I² = 86%; studies = 14; participants = 1790; low certainty evidence). We found no evidence for the outcome of quality of life. For those outcomes for which we were able to perform subgroup analyses, we found no evidence of interaction with stone location, stone size or type of alpha-blocker. We were unable to conduct an analysis by lithotripter type. The results were also largely unchanged when the analyses were limited to placebo controlled studies and those in which participants explicitly only received a single SWL session.

AUTHORS' CONCLUSIONS

Based on low certainty evidence, adjuvant alpha-blocker therapy following SWL in addition to usual care may result in improved stone clearance, less need for auxiliary treatments, fewer major adverse events and a reduced stone clearance time compared to usual care alone. We did not find evidence for quality of life. The low certainty of evidence means that our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect.

Animal Models for Studying Stone Disease

Animals have stone disease too. There are several animal models for the research of human stone disease. Rodents are the most frequently used for stone research, although they are not prone to forming crystals in the kidneys. Ethylene glycol (EG), sodium oxalate and l-hydroxyproline are common lithogenic agents. Dogs and pigs were also reported as a study animal for stone disease. However, the breeding costs and body size are too high. The most-used genetic study animal for stone disease was the mouse, but it was high-cost. Calcium oxalate (CaOx) crystals can also be light microscopically observed in the Malphigian tubules of Drosophila melanogaster, induced by adding EG to the food. Genetic studies of flies can be done by cross-breeding, and this has a lower cost than using mice. The fly model also has several advantages, including minimal breeding equipment, the fact that it is easier to reach larger numbers in a short time with flies, that crystals can be observed under microscopy, and that they allow genetic study. We suggest the fly will be an ideal animal model for stone research in the future.

The modulation of ureteral smooth muscle contractile responses by α1- and α2-adrenoceptor activation

PURPOSE

This study was performed to investigate the influence of α-adrenoceptor subtypes upon ureteral smooth muscle contractile responses.

METHODS

Rat ureters were challenged in vitro with noradrenaline (NA), the α₁-adrenoceptor agonist phenylephrine (PE), and the α₂-adrenoceptor agonist clonidine (CLON). The influences of the agonists on the magnitude and frequency of acetylcholine (ACh)-stimulated phasic contractile responses were recorded.

RESULTS

The magnitude of the phasic contractile responses effected by ACh was not significantly influenced by the adrenoceptor agonists, but the frequency of the response was significantly enhanced by all three agonists (p < 0.05). Idazoxan and prazosin abolished the rise in frequency effected by CLON and PE, respectively, whereas both antagonists in combination were required to abolish the increase in frequency effected by NA.

CONCLUSIONS

It has been demonstrated that α₁- and α₂-adrenoceptors modulate the contractile function of rat ureteral smooth muscle by increasing the frequency, but not the magnitude, of phasic contractile responses. The enhancement of contractile function by NA is mediated by mechanisms dependent upon both α₁- and α₂-adrenoceptors.

Pharmacological modulation of ureteric peristalsis in a chronically instrumented conscious pig model: effect of adrenergic and nitrergic modulation

PURPOSE

To evaluate the role of adrenergic and nitrergic signaling on ureteric peristaltic frequency and contraction force in vivo using a large animal model.

METHODS

Twelve female pigs (72 ± 4 kg) were chronically instrumented with an electronic pressure-monitoring catheter in the right ureter. Nephrostomy, cystostomy, and arterial and venous catheters were left in situ. Ureteral peristalsis was recorded before and after the administration of propranolol, isoprenaline, doxazosin, urapidil, phenylephrine, LNNA (Nω-nitro-L-arginine), and L-arginine.

RESULTS

α1-Adrenergic receptor stimulation resulted in an increased P max and peristaltic frequency. However, α1-inhibition decreased P max alone. Similarly, β-adrenergic stimulation decreased P max and peristaltic frequency, whereas β-inhibition increased only P max. LNNA administration increased P max in the distal ureter and hydrostatic pressure in the pyelocalyceal system. L-Arginine did not affect P max or frequency, but resulted in a significantly higher diuresis. Either agonist or antagonist of NO did not affect peristaltic frequency and length of contraction.

CONCLUSIONS

Activation of α- and β-adrenergic receptors, respectively, stimulates and inhibits ureteric peristalsis. The biological effect of NO on ureteric motility is regionally determined and corresponds to the distribution of NOS-positive nerves. Inhibition of NOS activity increases P max in the distal ureter and tonic activity of the ureteric muscle resulting in higher hydrostatic pressure in the renal pelvis.

Hydrogen sulfide plays a key role in the inhibitory neurotransmission to the pig intravesical ureter

According to previous observations nitric oxide (NO), as well as an unknown nature mediator are involved in the inhibitory neurotransmission to the intravesical ureter. This study investigates the hydrogen sulfide (H₂S) role in the neurogenic relaxation of the pig intravesical ureter. We have performed western blot and immunohistochemistry to study the expression of the H₂S synthesis enzymes cystathionine γ-lyase (CSE) and cystathionine β-synthase (CBS), measurement of enzymatic production of H₂S and myographic studies for isometric force recording. Immunohistochemical assays showed a high CSE expression in the intravesical ureter muscular layer, as well as a strong CSE-immunoreactivity within nerve fibres distributed along smooth muscle bundles. CBS expression, however, was not consistently observed. On ureteral strips precontracted with thromboxane A₂ analogue U46619, electrical field stimulation (EFS) and the H₂S donor P-(4-methoxyphenyl)-P-4-morpholinylphosphinodithioic acid (GYY4137) evoked frequency- and concentration-dependent relaxations. CSE inhibition with DL-propargylglycine (PPG) reduced EFS-elicited responses and a combined blockade of both CSE and NO synthase (NOS) with, respectively, PPG and N^G-nitro-L-arginine (L-NOARG), greatly reduced such relaxations. Endogenous H₂S production rate was reduced by PPG, rescued by addition of GYY4137 and was not changed by L-NOARG. EFS and GYY4137 relaxations were also reduced by capsaicin-sensitive primary afferents (CSPA) desensitization with capsaicin and blockade of ATP-dependent K⁺ (K_ATP) channels, transient receptor potential A1 (TRPA₁), transient receptor potential vanilloid 1 (TRPV₁), vasoactive intestinal peptide/pituitary adenylyl cyclase-activating polypeptide (VIP/PACAP) and calcitonin gene-related peptide (CGRP) receptors with glibenclamide, HC030031, AMG9810, PACAP_6–38 and CGRP_8–37, respectively. These results suggest that H₂S, synthesized by CSE, is involved in the inhibitory neurotransmission to the pig intravesical ureter, through an NO-independent pathway, producing smooth muscle relaxation via K_ATP channel activation. H₂S also promotes the release of inhibitory neuropeptides, as PACAP 38 and/or CGRP from CSPA through TRPA₁, TRPV₁ and related ion channel activation.

Pre- and post-junctional bradykinin B2 receptors regulate smooth muscle tension to the pig intravesical ureter

AIMS

Neuronal and non-neuronal bradykinin (BK) receptors regulate the contractility of the bladder urine outflow region. The current study investigates the role of BK receptors in the regulation of the smooth muscle contractility of the pig intravesical ureter.

METHODS

Western blot and immunohistochemistry were used to show the expression of BK B1 and B2 receptors and myographs for isometric force recordings.

RESULTS

B2 receptor expression was consistently detected in the intravesical ureter urothelium and smooth muscle layer, B1 expression was not detected where a strong B2 immunoreactivity was observed within nerve fibers among smooth muscle bundles. On ureteral strips basal tone, BK induced concentration-dependent contractions, were potently reduced by extracellular Ca(2+) removal and by B2 receptor and voltage-gated Ca(2+) (VOC) channel blockade. BK contraction did not change as a consequence of urothelium mechanical removal or cyclooxygenase and Rho-associated protein kinase inhibition. On 9,11-dideoxy-9a,11a-methanoepoxy prostaglandin F2α (U46619)-precontracted samples, under non-adrenergic non-cholinergic (NANC) and nitric oxide (NO)-independent NANC conditions, electrical field stimulation-elicited frequency-dependent relaxations which were reduced by B2 receptor blockade. Kallidin, a B1 receptor agonist, failed to increase preparation basal tension or to induce relaxation on U46619-induced tone.

CONCLUSIONS

The present results suggest that BK produces contraction of pig intravesical ureter via smooth muscle B2 receptors coupled to extracellular Ca(2+) entry mainly via VOC (L-type) channels. Facilitatory neuronal B2 receptors modulating NO-dependent or independent NANC inhibitory neurotransmission are also demonstrated.

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.

[From lab to clinical activity: adrenergic receptors and human uro-genital tissues]

BACKGROUND

Nowadays translational medicine is acquiring a more and more important role in connecting laboratory experimental results on human tissues to clinical findings and drug employment. We want to underline the importance of in vitro studies, which have been extensively performed on animal organs, but few studies have been performed on human tissues. Nevertheless, a more accurate result when compared to the in vivo use of drugs can be given only by testing the very same human tissues in a lab. We related clinical treatments of different pathologies with the results obtained in laboratory studying in vitro fragments of human organs extracted during surgery exposed to different mediators and drugs.

METHODS

Fragments of urethers, bladder (detrusorial muscle and bladder neck muscle fibers), corpora cavernosa, and vas deferens were extracted during demolitive surgery trying not to traumatize the tissue, in order to keep it alive and not to ruin its contractile fibers. The fragments were then put into polisaline solution and, once in the laboratory, fixed on suitable isolated organ support, fixed at one side of the thermostatic pool and on the other side connected to a digital monitoring system. The contractility was then studied after adding different mediators.

RESULTS

The urethers have shown a stronger response to NE and PGF2a, with a different contractility in their distal part due to a major concentration of alpha-receptors; the bladder neck has also shown a strong contractile response to NE and PGF2a, and is inhibited by alpha-blockers; the bladder detrusor, instead, responds to ACH (acetylcholine) and PGF2a; the vas deferens shows a different type of contractility in the prostatic part compared to the epididimary part when stimulated with noradrenaline and PGF2a; the corpora cavernosa respond to NE and PGF2a.

CONCLUSIONS

The results obtained after stimulating the fragments can explain and prove the receptorial activity of inner mediators and of commonly used drugs which have, for years, been used empirically; the simplicity and repetitivity of the method can be considered and used not only to research the physiological functioning of different organs, but also the functioning of new drugs before testing them on patients, being more reliable and accurate than tests on animal tissues. This experimental work has shown that using human tissues in testing specific mediators is the most reliable laboratory method.

β-Adrenergic Receptor Subtypes in the Urinary Tract

Within the urinary tract, β-adrenergic receptors (AR) are found largely on smooth muscle cells but are also present, at least in the bladder, in the urothelium and on afferent nerves. Our understanding of β-AR subtype expression and function is hampered by a lack of well-validated tools, particularly with regard to β(3)-AR. Moreover, the β-AR subtypes involved in a specific function may differ between species. In the ureter, β-AR can modulate pacemaker activity and smooth muscle tone involving multiple subtypes. In the human bladder, β-AR promote urine storage. Bladder smooth muscle relaxation primarily involves β(3)-AR, and the agonists selective for this subtype are in clinical development to treat bladder dysfunction. While prostate and urethra also express β-AR, the overall physiological role in these tissues remains unclear.

Tamsulosin as an expulsive therapy for steinstrasse after extracorporeal shock wave lithotripsy: a randomized controlled study

OBJECTIVE

Steinstrasse is a well-known complication following extracorporeal shockwave lithotripsy (ESWL). The objective of this study was to evaluate the efficacy of tamsulosin as a management of steinstrasse.

MATERIAL AND METHODS

88 patients with unilateral steinstrasse were treated between January 2005 and December 2008. The patients were randomly allocated into two equal groups. There were no significant differences between groups for age, gender, stone location, stone length or stone fragment size (p > 0.05). Patients in group 1 (study group) received a single daily morning dose of tamsulosin (0.4 mg) for a maximum of 4 weeks, in addition to pain-relieving therapy. Patients in group 2 (control group) received only the pain-relieving therapy. All patients were checked weekly with a plain X-ray of the urinary tract, urinary ultrasonography, urine analysis and serum creatinine. Pain episodes, day of spontaneous stone expulsion, total analgesic dosage and drug side-effects were recorded.

RESULTS

Stone expulsion occurred in 32 of the 44 patients (72.7%) receiving tamsulosin and in 25 of the 44 patients (56.8%) in the control group. Patients receiving tamsulosin had a significantly higher stone expulsion rate (p = 0.017). There were no significant differences between groups for mean stone expulsion time or number of analgesics used. Twelve patients (27.3%) in the group receiving tamsulosin and 19 patients (43.3%) in the control group needed hospitalization; the group difference was statistically significant (p = 0.017).

CONCLUSIONS

When compared with no treatment, tamsulosin can significantly facilitate expulsion of retained ureteral stone fragments following ESWL.

Endoluminal pelvic perfusion with norepinephrine causes only minor systemic effects and diminishes the increase in pelvic pressure caused by perfusion

OBJECTIVE

To evaluate the effect of endoluminal norepinephrine (NE) on transport pressures of the normal upper urinary tract of the pig and on plasma levels of NE in relation to possible systemic effects.

MATERIAL AND METHODS

Six anaesthetized pigs weighing approximately 39 kg were studied. Transparenchymally, two 6-F catheters were introduced into the renal pelvis bilaterally to measure pressure and perfusion. Ultrasonic flow probes recorded renal arterial blood flow, and a transurethral 10-F catheter drained the bladder and monitored diuresis. In all six animals, the bilateral pelvic pressure response was examined at increasing perfusion rates (2, 4, 6, 8, 10 and 15 ml/min) and with increasing doses of NE (0, 5, 50 and 100 microg/ml). Arterial blood samples were analysed for NE, epinephrine and blood glucose. The systemic blood pressure, heart rate and electrocardiogram were registered.

RESULTS

At all the investigated concentrations, endoluminal NE significantly diminished the increase in pelvic pressure caused by pelvic perfusion at all flow rates. At the lowest concentration of NE, no significant increase in the plasma level of NE was observed and the blood pressure did not increase. During perfusion with 50 and 100 microg/ml NE, plasma levels of NE increased significantly from 487+/-398 to 1798+/-910 and 2961+/-2093 pg/ml, respectively. This was accompanied by significant rises in mean systolic blood pressure from a baseline value of 95+/-10 mmHg to 111+/-20 and 118+/-23 mmHg, respectively. Heart rate, renal arterial blood flow and plasma levels of epinephrine and glucose did not change.

CONCLUSIONS

Endoluminal NE diminished the increase in pelvic pressure caused by pelvic perfusion even at concentrations too low to cause significant changes in NE plasma levels or systemic effects. Very high NE concentrations in the perfusion fluid caused increased plasma levels and a modest but significant increase in blood pressure. Administration of endoluminal NE may be useful in upper urinary tract stone treatment and endoscopy.

Mechanical function and gene expression of alpha(1)-adrenoceptor subtypes in dog intravesical ureter

OBJECTIVES

To characterize the contractile functions and gene expression of the alpha(1)-adrenoceptor (AR) subtypes present in the dog intravesical ureter.

METHODS

In a functional study, alpha(1)-AR antagonists were evaluated against phenylephrine (alpha(1)-AR agonist)-induced contractions in dog isolated intravesical ureteral preparations. The quantitative expression of alpha(1)-AR subtype mRNA in this tissue was determined using real-time quantitative reverse transcriptase-polymerase chain reaction.

RESULTS

In the isolated intravesical ureter, prazosin (nonselective alpha(1)-AR antagonist), silodosin (selective alpha(1A)-AR antagonist), naftopidil (selective alpha(1D)-AR antagonist), and BMY-7378 (selective alpha(1D)-AR antagonist) all shifted the concentration-contractile response curve for phenylephrine to the right. The rank order of potencies (pK(B) value) was silodosin (9.45 +/- 0.14), prazosin (8.16 +/- 0.08), naftopidil (7.39 +/- 0.19), and BMY-7378 (6.78 +/- 0.20). The alpha(1A)-AR antagonist silodosin was much more potent than the 2 alpha(1D)-AR antagonists. The rank order of mRNA expression levels among the alpha(1)-AR subtypes was alpha(1d) (72.68%), alpha(1a) (24.14%), and alpha(1b) (3.18%).

CONCLUSIONS

In the dog intravesical ureter, alpha(1A)-AR plays a major role in contraction, despite the prevalence of alpha(1D)-AR.

Role of Rho-kinase in contractions of ureters from rabbits with unilateral ureteric obstruction

OBJECTIVE

To investigate the expression of two isoforms of Rho-kinase (ROCK) and its functional role in the pathophysiological control of smooth muscle contraction in rabbits with unilateral ureteric obstruction (UUO).

MATERIAL AND METHODS

Left UUO was created in 14 rabbits and eight other rabbits (controls) had sham operations. After 2 weeks all the rabbits were killed. Ureteric strips suspended in an organ bath were used for functional studies and the effects of Y-27632, a specific inhibitor of Rho-kinase, on spontaneous contractions and electrical field stimulation (EFS; 50 V, 1 ms, 16 Hz, for 20 s), carbachol- (10(-7)-10(-4)m), phenylephrine- (10(-7)-10(-4)m) and KCl- (50 mm) induced contractions were analysed. Western blotting was used to determine expression levels of Rho-kinase protein in the ureters of UUO and control rabbits.

RESULTS

In the functional analysis, the contractions induced by EFS, KCl, phenylephrine and carbachol in the ureteric strips from rabbits with UUO were significantly greater than those from the control rabbits. Y-27632 considerably suppressed the ureter contractile responses in both UUO and control rabbits. Western blot analysis showed that both ROCK-1 and ROCK-2 proteins were expressed in the rabbit ureter. In accordance with the functional studies, the expression levels of both ROCK-1 and ROCK-2 were significantly greater in the ureters of UUO rabbits than in the controls.

CONCLUSIONS

Y-27632 suppressed ureteric contractions in the rabbits with UUO. Western blot analysis also confirmed greater expression levels of ROCK-1 and ROCK-2 in the ureters of UUO rabbits. It is important to elucidate by which mechanisms the Rho-kinase pathway affects ureteric function after obstruction.

Pre-junctional alpha2-adrenoceptors modulation of the nitrergic transmission in the pig urinary bladder neck

AIMS

To investigate the nitric oxide (NO)-mediated nerve relaxation and its possible modulation by pre-junctional alpha2-adrenoceptors in the pig urinary bladder neck.

METHODS

Urothelium-denuded bladder neck strips were dissected, and mounted in isolated organ baths containing a physiological saline solution (PSS) at 37 degrees C and continuously gassed with 5% CO2 and 95% O2, for isometric force recording. The relaxations to transmural nerve stimulation (electrical field stimulation [EFS]) or exogenously applied NO were carried out on strips pre-contracted with 1 microM phenylephrine (PhE) and treated with guanethidine (10 microM) and atropine (0.1 microM), to block noradrenergic neurotransmission and muscarinic receptors, respectively.

RESULTS

EFS (0.2-1 Hz, 1 msec duration, 20 sec trains, current output adjusted to 75 mA) evoked frequency-dependent relaxations which were abolished by the neuronal voltage-activated Na+ channel blocker tetrodotoxin (TTX, 1 microM). These responses were potently reduced by the nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine (L-NOARG, 30 microM) and further reversed by the NO synthesis substrate L-arginine (L-ARG, 3 mM). The alpha2-adrenoceptor agonist BHT-920 (2 microM) reduced the electrically evoked relaxations, its effectiveness being higher on the responses induced by low frequency stimulation. BHT-920-elicited reductions were fully reversed by the alpha2-adrenoceptor antagonist rauwolscine (RAW, 1 microM). Exogenous NO (1 microM-1 mM) induced concentration-dependent relaxations which were not modified by BHT-920, thus eliminating a possible post-junctional modulation.

CONCLUSIONS

These results indicate that NO is involved in the non-adrenergic non-cholinergic (NANC) inhibitory neurotransmission in the pig urinary bladder neck, the release of NO from intramural nerves being modulated by pre-junctional alpha2-adrenoceptor stimulation.

Current opinion in urology: new insights into nephrolithiasis

PURPOSE OF REVIEW

Recent studies in nephrolithiasis have investigated why stones form, improvements in medical therapy, and advances in surgical therapy. We outline recent research in these areas.

RECENT FINDINGS

We describe a series of articles characterizing the histopathology of Randall's plaques and the renal papillae in patients with nephrolithiasis, detailing genetic discoveries related to uric acid stones, describing further uses of alpha-antagonists in nephrolithiasis, and reporting improvements in extracorporeal shockwave lithotripsy technique and outcomes.

SUMMARY

Characterization of the renal papillae and Randall's plaques in different types of stones may guide the urologist in treating stones and may lead to further research into how and where stones of different compositions form.

Effect of tamsulosin on the number and intensity of ureteral colic in patients with lower ureteral calculus

BACKGROUND

We aimed to objectively determine whether tamsulosin as an alpha(1)-blocker was effective in patients who had ureterolithiasis located in the lower part of the ureter.

METHODS

Sixty patients with lower ureteral calculi (juxtavesical or intramural portion) were included in the present study. Conservative treatment, such as hydration and tenoxicam as a non-steroidal anti-inflammatory drug, was given to group 1 (30 patients). Group 2 (30 patients) was given tamsulosin (0.4 mg daily) in addition to the conservative treatment. All patients were followed up and questioned about the numbers and intensity of ureteral colic, and the rates of spontaneous passage after the procedure.

RESULTS

Spontaneous passage was observed in 22 of the 30 patients in group 1 (73.3%) and 26 of the 30 patients in group 2 (86.6%). The difference within groups 1 and 2 was not significant (P=0.196). The difference between both groups was not statistically significant either, with the stone diameter being 6 mm (P=0.635) or >6 mm (P=0.407). As group 1 patients were passing their stones, they had more ureteral colic episodes than group 2 patients. This difference was statistically significant and correlated well with the administration of tamsulosin (P=0.038). Group 1 patients reported higher scores according to a visual analog scale than group 2 patients. Also, this difference was statistically significant (P=0.000).

CONCLUSIONS

We think that the treatment of alpha(1)-blockers decreased the number of ureteral colic episodes and the intensity of pain during spontaneous passage at the lower ureteral calculi. Also, it will be beneficial to patients' quality of life.

PACAP 38 is involved in the non-adrenergic non-cholinergic inhibitory neurotransmission in the pig urinary bladder neck

AIMS

To investigate the role played by pituitary adenylate cyclase activating polypeptide 38 (PACAP 38) in the non-adrenergic non-cholinergic (NANC) neurotransmission of the pig urinary bladder neck.

METHODS

Urothelium-denuded bladder neck strips were dissected and mounted in organ baths containing a physiological saline solution (PSS) at 37 degrees C and gassed with 5% CO(2) and 95% O(2), for isometric force recording. The relaxations to transmural nerve stimulation (EFS) or PACAP 38 were performed on strips precontracted with 1 microM phenylephrine (PhE). EFS experiments were carried out in the absence and the presence of guanethidine (10 microM), atropine (0.1 microM), and N(G)-nitro-L-arginine (L-NOARG, 100 microM), to block noradrenergic neurotransmission, muscarinic receptors, and nitric oxide (NO) synthase, respectively.

RESULTS

EFS (2-16 Hz, 1 ms duration, 20 sec trains, 75 mA current output) evoked frequency-dependent relaxations which were reduced by the VIP/PACAP receptor antagonist PACAP (6-38) (3 microM), and by the neurotoxin of the capsaicin-sensitive primary afferents capsaicin (10 microM), and abolished by the neuronal voltage-activated Na(+) channel blocker tetrodotoxin (TTX, 1 microM). The vasoactive intestinal peptide (VIP) receptor antagonist [Lys(1), Pro(2,5), Arg(3,4), Tyr(6)]-VIP (3 microM) failed to modify the EFS-induced relaxations. PACAP 38 (1 nM-1 microM) induced concentration-dependent relaxations which were reduced by PACAP (6-38), TTX and by the neuronal voltage-gated Ca(2+) channel inhibitor omega-conotoxin GVIA (omega-CgTX, 1 microM).

CONCLUSIONS

The results suggest that PACAP 38, mainly released from capsaicin-sensitive primary afferents, is involved in the NANC inhibitory neurotransmission of the pig urinary bladder neck, producing relaxation through neuronal and muscle VIP/PACAP receptor activation.

Role of tamsulosin in treatment of patients with steinstrasse developing after extracorporeal shock wave lithotripsy

OBJECTIVES

To evaluate whether tamsulosin, as an alpha(1)-blocker, was effective for the treatment of steinstrasse in the lower ureter after shock wave lithotripsy.

METHODS

A total of 67 patients (43 men and 24 women) with steinstrasse in the lower portion of the ureters were randomly divided into two groups. Only hydration and tenoxicam (20 mg orally once daily) was given to group 1 (35 patients). Group 2 (32 patients), was also given tamsulosin (0.4 mg daily). All patients were reevaluated and questioned about the number of episodes and severity of ureteral colic and the rates of spontaneous resolution of steinstrasse 6 weeks after beginning treatment. They were asked to score the severity of pain according to a visual analog scale.

RESULTS

In 23 (65.7%) of 35 patients in group 1 and in 24 (75%) of 32 patients in group 2, steinstrasse resolved during the first 6 weeks. The resolution rates were not significantly different (P >0.05) between groups 1 and 2. Group 1 had more ureteral colic episodes than did group 2 while passing their stones. This difference was statistically significant (P <0.01). Group 1 patients reported significantly greater (P <0.001) visual analog scale scores than did group 2 patients.

CONCLUSIONS

The addition of tamsulosin to conservative treatment seemed to be beneficial in terms of the reduced number of ureteral colic episodes and the severity of pain in the patients who developed steinstrasse after shock wave lithotripsy.

RANDOMIZED TRIAL OF THE EFFICACY OF TAMSULOSIN, NIFEDIPINE AND PHLOROGLUCINOL IN MEDICAL EXPULSIVE THERAPY FOR DISTAL URETERAL CALCULI

PURPOSE

Recent studies show the interesting efficacy of different drug combinations for the spontaneous expulsion of distal ureteral stones. We performed a randomized, prospective study to assess and compare the efficacy of 3 drugs as medical expulsive therapy for distal ureteral calculi.

MATERIALS AND METHODS

A total of 210 symptomatic patients with distal ureteral calculi greater than 4 mm were randomly allocated to home treatment with phloroglucinol, tamsulosin or nifedipine (groups 1 to 3, respectively). Each group was given a corticosteroid drug and antibiotic prophylaxis with an injectable nonsteroidal anti-inflammatory drug was also used on demand. The primary end point was the expulsion rate and the secondary end points were expulsion time, analgesic use, need for hospitalization and endoscopic treatment as well as the number of workdays lost, quality of life and drug side effects

RESULTS

The expulsion rate was significantly higher in group 2 (97.1%) than in groups 1 (64.3%, p <0.0001) or 3 (77.1%, p <0.0001). Group 2 significantly achieved stone passage in a shorter time than the other 2 groups and showed a significantly decreased number of hospitalizations as well as a better decrease in endoscopic procedures performed to remove the stone. The control of renal colic pain was significantly superior in group 2 compared with the other groups, resulting in fewer workdays lost. Group 3 showed lower analgesic use and decreased workdays lost compared with group 1. No difference in side effects was observed among the groups.

CONCLUSIONS

Medical expulsive therapy should be considered for distal ureterolithiasis without complications before ureteroscopy or extracorporeal lithotripsy. The use of tamsulosin in this treatment regimen produced stone expulsion in almost all cases in a short time, allowing complete home patient treatment.

Evidence for the presence of alpha1 adrenoceptor subtypes in the human ureter

AIM

Several studies have proposed a role for alpha1 adrenoceptors (ARs) in ureteral physiology, indicating that they are present in the ureter; however, few studies have been done to identify alpha1 AR subtypes present in this area. Thus, this study was carried out to characterize the alpha1 AR subtype gene and protein expression in proximal, medial, and distal region of the human ureter.

METHODS

Molecular characterization of alpha1 AR subtypes were analyzed by semi-quantitative RT-PCR. alpha1 AR protein expression was studied by saturation binding curves and by competition binding curves with selective antagonists. Analysis of data was performed using the GraphPad PRISM 4 software.

RESULTS

Analysis of saturation binding curves revealed a heterogeneous distribution of alpha1 AR binding sites, the B(max) for the distal ureter was indeed 52.5 +/- 5.4 fmol/mg prot, while a lower similar density of alpha1 ARs was demonstrated in the medial (25.2 +/- 1.7 fmol/mg prot) and proximal (23.4 +/- 0.4 fmol/mg prot) ureters. Molecular and pharmacological characterization of alpha1 AR subtypes indicated that each receptor was present, although with differences in terms of the amount expressed.

CONCLUSIONS

Human ureter was endowed with each alpha1 AR subtype, although alpha1D and alpha1A ARs were prevalent over alpha1B ARs. Radioligand binding results revealed that there were no significant differences in the K(d) between ureteral regions, while a heterogeneous distribution of alpha1 AR binding sites was detected, with the highest density of alpha1 ARs in the distal ureter and a lower similar density in the medial and proximal ureters.

Evidence for the Presence of α1 Adrenoceptor Subtypes in the Human Ureter

Several studies proposed a role for α1 adrenoceptors (α1 ARs) in the ureteral physiology, indicating that they are present in the ureter; however, few studies have been made to identify α1 AR subtypes present in this area. Thus, this study was carried out to characterize the α1 AR subtype gene and protein expression in proximal, medial and distal region of the human ureter.

Methods

Molecular characterization of α1 AR subtypes was done by semi-quantitative RT-PCR. The α1 AR protein expression was studied by saturation binding curves using the α1 AR antagonist 125I-HEAT. Analysis of data was performed using the GraphPad PRISM 4 software.

Results

Analysis of saturation binding curves revealed an heterogeneous distribution of α1 AR binding sites; the Bmax for the distal ureter was indeed 52.5 ±5.4 fmol/mg prot, while a lower similar density of α1 ARs was demonstrated in the medial (25.2 ±1.7 fmol/mg prot) and proximal (23.4 ±0.4 fmol/mg prot) ureters. Molecular characterization of α1 AR subtypes indicated that each receptor was present, although with differences in term of the amount expressed.

Conclusions

Human ureter was endowed with each α1 AR subtype, although α1D and α1A ARs were prevalent over α1B ARs. Radioligand binding results revealed that there were no significant differences in the Kd between ureteral regions, while an heterogeneous distribution of α1 AR binding sites was detected, with the highest density of α1 ARs in the distal ureter and a lower similar density in the medial and proximal ureter.

Expression of Rho-kinase (ROCK-1 and ROCK-2) and its substantial role in the contractile activity of the sheep ureter

Expression of two isoforms of Rho-kinase (ROCK) and its functional role in the physiological control of smooth muscle contraction in the sheep ureter were investigated. Helical strips of the ureteric smooth muscle were stimulated by electrical field stimulation (EFS, 60 V, 1 mS, 2, 4, 8, 16 and 32 Hz, for 20 S), KCl (80 mm), carbachol (CCh, 10(-8)-10(-4) m) or phenylephrine (Phe, 10(-8)-10(-4) m). EFS produced a reproducible contractile activity, which was abolished by tetrodotoxin (3 x 10(-6) m), a Na(+) channel blocker. A muscarinic receptor antagonist, atropine (2 x 10(-6) m), and an adrenergic neuron blocker, guanethidine (10(-5) m), significantly suppressed the contraction induced by EFS. However, this contraction was augmented in the presence of N(G)-nitro-l-arginine (l-NA, 10(-4) m), a nitric oxide synthase inhibitor. Two Rho-kinase inhibitors, Y-27632 (5 x 10(-5) m) and fasudil (5 x 10(-5) m), markedly attenuated the EFS-elicited contraction. CCh and Phe produced concentration-dependent contraction in the sheep ureter. pD(2) values for Phe and CCh were 5.04+/-0.11 and 5.00+/-0.22, respectively. Y-27632 (5 x 10(-5) m) and fasudil (5 x 10(-5) m) also significantly inhibited CCh- and Phe-induced contractions. Moreover, these ROCK inhibitors produced relaxations in the KCl-elicited contraction in a concentration-dependent manner. pD(2) values for Y-27632 and fasudil were, respectively, 5.17+/-0.07 and 4.58+/-0.08 (P<0.001). Furthermore, the influences of these agents were also tested on spontaneous phasic contractions of the tissue. Among Y-27632, fasudil, TTX, l-NA, guanethidine and atropine, only the ROCK inhibitors (10(-6)-10(-5) m) were able to suppress the spontaneous contractile activity. Western blot analysis has revealed that both isoforms of Rho-kinase (ROCK-1 and ROCK-2) are expressed in the sheep ureter. Densitometric analysis has indicated that these enzymes are less expressed in the sheep ureter than are in the sheep aorta in a significant manner. These results show that a contractile enzyme, Rho-kinase, is expressed, and it mediates agonist- and EFS-induced contractions as well as spontaneous contractile activity of the isolated sheep ureter. Since Y-27632 and fasudil depressed the contractions, it seems plausible to postulate that Rho-kinase inhibitors may be beneficial in the treatment of renal colic.

Heterogeneity of neuronal and smooth muscle receptors involved in the VIP- and PACAP-induced relaxations of the pig intravesical ureter

1. The mechanisms and receptors involved in the vasoactive intestinal peptide (VIP)- and pituitary adenylate cyclase-activating polypeptide (PACAP)-induced relaxations of the pig intravesical ureter were investigated. 2. VIP, PACAP 38 and PACAP 27 concentration-dependently relaxed U46619-contracted ureteral strips with a similar potency. [Ala(11,22,28)]-VIP, a VPAC(1) agonist, showed inconsistent relaxations. 3. The neuronal voltage-gated Ca(2+) channel inhibitor, omega-conotoxin GVIA (omega-CgTX, 1 microm), reduced the VIP relaxations. Urothelium removal or blockade of capsaicin-sensitive primary afferents, nitric oxide (NO) synthase and guanylate cyclase with capsaicin (10 microm), N(G)-nitro-l-arginine (l-NOARG, 100 microm) and 1H-[1,2,4]-oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 5 microm), respectively, did not change the VIP relaxations. However, the PACAP 38 relaxations were reduced by omega-CgTX, capsaicin, l-NOARG and ODQ. 4. The VIP and VIP/PACAP receptor antagonists, [Lys(1), Pro(2,5), Arg(3,4), Tyr(6)]-VIP (1 microm) and PACAP (6-38) (0.4 microm), inhibited VIP and VIP and PACAP 38, respectively, relaxations. 5. The nonselective and large-conductance Ca(2)-activated K(+) channel blockers, tetraethylammonium (3 mm) and charybdotoxin (0.1 microm), respectively, and neuropeptide Y (0.1 microm) did not modify the VIP relaxations. The small-conductance Ca(2)-activated K(+) channel blocker apamin (1 microm) did not change the PACAP 27 relaxations. 6. The cAMP-dependent protein kinase A (PKA) blocker, 8-(4-chlorophenylthio)adenosine-3',5'-cyclic monophosphorothioate (Rp-8-CPT-cAMPS, 100 microm), reduced VIP relaxations. The phosphodiesterase 4 inhibitor rolipram and the adenylate cyclase activator forskolin relaxed ureteral preparations. The rolipram relaxations were reduced by Rp-8-CPT-cAMPS. Forskolin (30 nm) evoked a potentiation of VIP relaxations. 7. These results suggest that VIP and PACAP relax the pig ureter through smooth muscle receptors, probably of the VPAC(2) subtype, linked to a cAMP-PKA pathway. Neuronal VPAC receptors localized at motor nerves and PAC(1) receptors placed at sensory nerves and coupled to NO release, seem also to be involved in the VIP and PACAP 38 relaxations.

Pharmacological profile of KUL-7211, a selective beta-adrenoceptor agonist, in isolated ureteral smooth muscle

Since, in the human ureter, both beta(2)- and beta(3)-adrenoceptors mediate adrenergic-stimulation-induced relaxation, selective beta(2)-/beta(3)-adrenoceptor agonists might prove clinically useful for relieving ureteral colic and promoting stone passage. We evaluated the beta-adrenoceptor subtype selectivity and ureteral-relaxing efficacy of (-)-2-[4-(2-[[(1S,2R)-2-hydroxy-2-(4-hydroxyphenyl)-1-methylethyl]amin] ethyl)phenyloxy]acetic acid (KUL-7211), a new beta-adrenoceptor agonist, in vitro. In rat isolated organs, its selectivities, for inhibition of spontaneous uterine contraction (mediated via beta(2)-adrenergic stimulation) and inhibition of colonic contraction (via beta(3)-adrenergic stimulation) versus increase in atrial rate (via beta(1)-adrenergic stimulation), were 56.3 and 242.2, respectively. KUL-7211 relaxed 80-mM-KCl-induced tonic contractions in both rabbit (pD(2) value: 5.86 +/- 0.13, whose ureteral relaxation is mediated via beta(2)-adrenergic stimulation) and canine (pD(2) value: 6.52 +/- 0.16, via beta(3)-adrenergic stimulation) isolated ureters in a concentration-dependent manner. These KUL-7211-induced relaxing effects were antagonized by ICI-118,551 (selective beta(2)-adrenoceptor antagonist, pK(B) value: 8.91 +/- 0.24) in the rabbit ureter and by bupranolol (non-selective beta-adernoceptor antagonist, pK(B) value: 6.85 +/- 0.12) in the canine ureter. KUL-7211 also reduced the spontaneous rhythmic contraction in a canine ureteral spiral preparation in a concentration-dependent manner, the pD(2) value being 6.83 +/- 0.20. These data clearly demonstrate that KUL-7211 selectively stimulates both ureteral beta(2)- and beta(3)-adrenoceptors and potently relaxes ureteral smooth muscle. KUL-7211 may be a novel and useful medication for relieving ureteral colic and promoting stone passage in urolithiasis patients.

Characterization of the 5-hydroxytryptamine receptors mediating contraction in the pig isolated intravesical ureter

1 This study was designed to investigate the effect of 5-hydroxytryptamine (5-HT) and to characterize the 5-HT receptors involved in 5-HT responses in the pig intravesical ureter. 2 5-HT (0.01-10 microM) concentration-dependently increased the tone of intravesical ureteral strips, whereas the increases in phasic contractions were concentration-independent. The 5-HT(2) receptor agonist alpha-methyl 5-HT, mimicked the effect on tone whereas weak or no response was obtained with 5-CT, 8-OH-DPAT, m-chlorophenylbiguanide and RS 67333, 5-HT(1), 5-HT(1A), 5-HT(3) and 5-HT(4) receptor agonists, respectively. 5-HT did not induce relaxation of U46619-contracted ureteral preparations. Pargyline (100 microM), a monoaminooxidase A/B activity inhibitor, produced leftward displacements of the concentration-response curves for 5-HT. 3 5-HT-induced tone was reduced by the 5-HT(2) and 5-HT(2A) receptor antagonists ritanserine (0.1 microM) and spiperone (0.2 microM), respectively. However, 5-HT contraction was not antagonized by cyanopindolol (2 microM), SDZ-SER 082 (1 microM), Y-25130 (1 microM) and GR 113808 (0.1 microM), which are respectively, 5-HT(1A/1B), 5-HT(2B/2C), 5-HT(3), and 5-HT(4) selective receptor antagonists. 4 Removal of the urothelium did not modify 5-HT-induced contractions. Blockade of neuronal voltage-activated sodium channels, alpha-adrenergic receptors and adrenergic neurotransmission with tetrodotoxin (1 microM), phentolamine (0.3 microM) and guanethidine (10 microM), respectively, reduced the contractions to 5-HT. However, physostigmine (1 microM), atropine (0.1 microM) and suramin (30 microM), inhibitors of cholinesterase activity, muscarinic- and purinergic P(2)-receptors, respectively, failed to modify the contractions to 5-HT. 5 These results suggest that 5-HT increases the tone of the pig intravesical ureter through 5-HT(2A) receptors located at the smooth muscle. Part of the 5-HT contraction is indirectly mediated via noradrenaline release from sympathetic nerves.

Modification of ureteral motility and promotion of urine flow around an intraureteral obstruction by CL-316243, phenylephrine, and furosemide in dogs

The aim of this study was to evaluate the effects of a beta3-adrenoceptor (AR) agonist (CL-316243), an alpha1-AR agonist (phenylephrine), and a loop diuretic (furosemide) on the spontaneous rhythmic contractions of the isolated canine ureter and on an acute ureteral obstruction produced by inflation of a balloon catheter in anesthetized dogs. In the isolated ureter, CL-316243 concentration dependently reduced both the amplitude and frequency of the rhythmic contractions (pD(2): 7.19 +/- 0.33), whereas phenylephrine significantly enhanced both variables (pD(2): 5.26 +/- 0.09) and furosemide reduced them only slightly. In the acute ureteral obstruction model, the intraureteral pressure (IUP) gradually rose to reach a plateau of 58.9 mm Hg after inflation of a balloon catheter within the lower ureter. Intravenous administration of CL-316243 (0.3 microg/kg) significantly reduced the elevated IUP and the resumed urine flow (UF), leading to a sustained reduction in the IUP. In contrast, the IUP continued to increase above the plateau level for 10 minutes after phenylephrine administration (10 microg/kg) and for 30 minutes after furosemide administration (1,000 microg/kg). In the phenylephrine group, the UF resumed when the IUP reached 75.8 mm Hg, and thereafter the IUP gradually decreased in parallel with the increase in the UF. From these results, we conclude that in dogs, CL-316243 reduces the IUP by allowing the UF to resume as a result of a relaxation of ureter at the obstruction site, whereas with phenylephrine, the reduction in the IUP is secondary to a resumption in the UF resulting from an induced contraction of ureter that causes an increase in hydrostatic pressure above the obstruction site.

Systemic and topical drug administration in the pig ureter: effect of phosphodiesterase inhibitors alpha1, beta and beta2-adrenergic receptor agonists and antagonists on the frequency and amplitude of ureteral contractions

PURPOSE

We searched for compounds that are pharmacologically active on ureteral motility for treating ureteral colic to ease retrograde access into the ureter and improve the clearance of stones or stone particles from the ureter. The effects of the alpha1-adrenergic receptor agonist phenylephrine, the nonselective beta and beta2-adrenergic receptor agonists isoproterenol and fenoterol, and the phosphodiesterase inhibitors papaverine (nonspecific) and rolipram (type IV) on the frequency and amplitude of ureteral contractions when administered intravenously or topically were investigated in pigs.

MATERIALS AND METHODS

A total of 52 pigs were anesthetized. A double lumen 6Fr catheter was inserted through each renal pelvis and into the ureter, allowing perfusion of saline or drug solution into the renal pelvis and the recording of contractions from the mid portion of the ureter.

RESULTS

The alpha1 and beta-adrenergic receptors of the ureter are not tonically activated by endogenous epinephrine or norepinephrine. Phenylephrine administered intravenously at a dose of 0.01 to 3 mg./kg. and topically at 0.1 to 3 mg./ml. per minute increased contraction frequency 10 and 4-fold, respectively, and contraction amplitude 2-fold each in a dose dependent manner. Arterial blood pressure increased markedly during intravenous administration of phenylephrine but was minimally affected during topical application. The phenylephrine effects were reversed by the antagonist prazosin. Isoproterenol administered intravenously at a dose of 0.01 to 10 mg./kg. and topically at 0.1 to 200 microg./ml. per minute decreased contraction frequency to 13% and 31% of controls, respectively. Contraction amplitude was not affected by intravenous administration but decreased to 59% of controls when applied topically. These effects were also observed with a slight delay in the saline perfused contralateral ureter. The heart rate also increased, suggesting absorption of the drug by the urothelium. The isoproterenol effects were blocked by the antagonist propranolol. Fenoterol administered intravenously at a dose of 0.1 to 30 microg./kg. and topically at 0.003 to 1 mg./ml. per minute decreased contraction frequency to 14% and 10% of controls, and contraction amplitude to 84% and 65%, respectively. These effects on the drug perfused ureter were also observed on the contralateral saline perfused ureter but to a lesser extent. The fenoterol effects were blocked by the antagonist propranolol. Papaverine administered intravenously at a dose of 0.001 to 3 mg./kg. decreased contraction frequency to 33% of controls. Topically administered papaverine as well as intravenous and topically administered rolipram had no relevant effect on ureteral motility.

CONCLUSIONS

Intravenous phenylephrine increases, and isoproterenol and fenoterol decrease the frequency and amplitude of ureteral contractions in the pig. The same effects are observed with the topical administration of phenylephrine, which causes a significant local but not systemic side effect. Topical administration of isoproterenol and fenoterol produced local as well as systemic effects, suggesting absorption by the urothelium. However, to our knowledge a drug that relaxes ureteral peristalsis in pigs without causing systemic side effects has not yet been identified.

NK2 tachykinin receptors mediate contraction of the pig intravesical ureter: tachykinin-induced enhancement of non-adrenergic non-cholinergic excitatory neurotransmission

The current study was designed to characterize the functionally active tachykinin receptors involved in tachykinin-elicited contractions in the pig intravesical ureter, and to investigate the possible modulation exerted by the natural tachykinins substance P (SP) and neurokinin A (NKA) on the non-adrenergic non-cholinergic (NANC) excitatory ureteral neurotransmission. In pig intravesical ureteral strips pretreated with phosphoramidon (10(-5) mol/L) to block the endopeptidase activities, isometric force recordings showed that SP, NKA, and the NK2 receptor selective agonist [beta-Ala(8)]-NKA (4-10), all three induced contractions, with the following potency order: NKA > [beta-Ala(8) ]-NKA (4-10) > SP. [Sar(9), Met(O(2))(11)]-SP and senktide, selective agonists of the NK1 and NK3 receptors, respectively, failed to modify the ureteral tone. Urothelium removal and incubation with tetrodotoxin (10(-6) mol/L), phentolamine (10(-7) mol/L), propranolol (3 x 10(-6) mol/L), atropine (10(-7) mol/L) and indomethacin (3 x 10(-6) mol/L), did not alter the contraction induced by a submaximal (10(-7) mol/L) dose of [beta-Ala(8)]-NKA (4-10). MEN 10,376 (10(-8)-10(-7) mol/L), a NK2 receptor antagonist, reduced the contraction to 3 x 10(-8) mol/L NKA. GR 82334 (10(-6) -10(-5) mol/L) and SR 142801 (10(-8)-10(-7) mol/L), selective antagonists of the NK1 and NK3 receptors, respectively, did not modify that contraction. In pig intravesical ureteral strips in NANC conditions, SP and NKA induced a potentiation of the contractions to electrical field stimulation (EFS) and to exogenous ATP. The results suggest that the tachykinins evoke a direct contraction of pig intravesical ureteral strips through NK2 receptors located in the smooth muscle. SP and NKA exert an enhancement of the NANC excitatory neurotransmission of the pig intravesical ureter.

Localization of nitric oxide synthase and haemoxygenase, and functional effects of nitric oxide and carbon monoxide in the pig and human intravesical ureter

The distribution of nitric oxide synthase (NOS)-immunoreactive (IR) and haemoxygenase (HO)-IR nerves was investigated in the pig and human intravesical ureter (IVU). NOS activity was measured by monitoring the conversion of [3H]-arginine to [3H]-citrulline. Effects of NO and resulting changes in cyclic nucleotide concentrations were assessed in vitro. The effects of carbon monoxide (CO) on IVU motility was also tested. Immunohistochemistry revealed an abundant overall innervation of the IVU and numerous NOS-IR nerves. Nerve trunks were also found expressing immunoreactivity for HO-1, one of the enzymes synthetising CO. Similar profiles of nerve structures expressing immunoreactivities for NOS and tyrosine-hydroxylase (TH), as well as NOS and vasoactive intestinal peptide (VIP) were demonstrated. In the pig IVU, measurement of NOS activity revealed a moderate calcium-dependent catalytic activity, NO and the NO-donor SIN-1 reduced in a concentration-dependent manner serotonin-induced contractions of pig and human IVU, and the spontaneous contractions of pig IVU. In pig IVU strips precontracted with the thromboxane analogue U-46619, tetrodotoxin-sensitive relaxations were abolished by the NOS inhibitor NG-nitro-L-arginine. CO exerted no significant effect on spontaneous or induced contractions in the pig and human IVU. In precontracted strips of the pig and human IVU exposed to SIN-1 or NO, significant increases of cyclic GMP levels were measured in comparison to control preparations. The results suggest that the L-arginine/NO/cyclic GMP pathway may play a role in the regulation of the valve function in the uretero-vesical junction (UVJ). A role for CO in the UVJ has yet to be established.

A2B adenosine receptors mediate relaxation of the pig intravesical ureter: adenosine modulation of non adrenergic non cholinergic excitatory neurotransmission

1. The present study was designed to characterize the adenosine receptors involved in the relaxation of the pig intravesical ureter, and to investigate the action of adenosine on the non adrenergic non cholinergic (NANC) excitatory ureteral neurotransmission. 2. In U46619 (10(-7) M)-contracted strips treated with the adenosine uptake inhibitor, nitrobenzylthioinosine (NBTI, 10(-6) M), adenosine and related analogues induced relaxations with the following potency order: 5'-N-ethylcarboxamidoadenosine (NECA) = 5'-(N-cyclopropyl)-carboxamidoadenosine (CPCA) = 2-chloroadenosine (2-CA) > adenosine > cyclopentyladenosine (CPA) = N6-(3-iodobenzyl)-adenosine-5'-N-methylcarboxamide (IB-MECA) = 2-[p-(carboxyethyl)-phenylethylamino]-5'-N-ethylcarboxamidoaden os ine (CGS21680). 3. Epithelium removal or incubation with indomethacin (3 x 10(-6) M) and L-N(G)-nitroarginine (L-NOARG, 3 x 10(-5) M), inhibitors of prostanoids and nitric oxide (NO) synthase, respectively, failed to modify the relaxations to adenosine. 4. 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, 10(-8) M) and 4-(2-[7-amino-2-(2-furyl) [1,2,4]-triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (ZM 241385, 3 x 10(-8) M and 10(-7) M), A1 and A2A receptor selective antagonists, respectively, did not modify the relaxations to adenosine or NECA. 8-phenyltheophylline (8-PT, 10(-5) M) and DPCPX (10(-6) M), which block A1/A2-receptors, reduced such relaxations. 5. In strips treated with guanethidine (10(-5) M), atropine (10(-7) M), L-NOARG (3 x 10(-5) M) and indomethacin (3 x 10(-6) M), both electrical field stimulation (EFS, 5 Hz) and exogenous ATP (10(-4) M) induced contractions of preparations. 8-PT (10(-5) M) increased both contractions. DPCPX (10(-8) M), NECA (10(-4) M), CPCA, (10(-4) M) and 2-CA (10(-4) M) did not alter the contractions to EFS. 6. The present results suggest that adenosine relaxes the pig intravesical ureter, independently of prostanoids or NO, through activation of A2B-receptors located in the smooth muscle. This relaxation may modulate the ureteral NANC excitatory neurotransmission through a postsynaptic mechanism.

Synthesis and beta-adrenergic properties of (Z)-N-[3-(alkylamino)-2-hydroxypropylidene](aryl-methyloxy)amines: effects of the configuration around the methyloxyiminomethyl (MOIM) double bond on the biopharmacological properties of MOIM-type beta-blocking agents

The N-isopropyl- (3a-g) and N-tert-butyl-substituted (4a-g) (Z)-N-(3-(amino)-2-hydroxypropylidene)-(arylmethyloxy)amines were synthesized in order to compare their beta 1- and beta 2-adrenergic properties with those of their previously studied corresponding analogues with the E configuration (1a-g and 2a-g). Compounds 3 and 4 were tested for their affinity for beta 1-a and beta 2-adrenoceptors by radioligand binding experiments, and the compounds with the highest affinity were also assayed for their activity towards the same types of beta-adrenoceptors by functional tests on isolated preparations. The Z-methyloxyiminomethyl (Z-MOIM) compounds 3 and 4 proved to possess, on the whole, affinity (Ki) and activity (PIC50) indices similar to those of the E isomers 1 and 2, thus indicating that for the MOIM-type beta-adrenergic antagonists 1-4, the type of configuration around the MOIM double bond does not have any appreciable effect either on the affinity or on the activity towards beta-adrenoceptors. These results are rationalized on the basis of the steric and electronic analogies existing between the MOIM groups of 1-4 in the two types of configurations (E and Z).

Beta-adrenoceptor subtypes in the ureteral smooth muscle of rats, rabbits and dogs

We investigated the beta-adrenoceptor subtypes mediating ureteral relaxation in rats, rabbits and dogs. The relaxing effects of beta-adrenoceptor agonists were evaluated on KCl-induced ureteral contractions. The rank order of potency of the catecholamines tested was isoprenaline > noradrenaline > adrenaline in rat ureter; isoprenaline > adrenaline > noradrenaline in rabbit ureter; only isoprenaline was effective in canine tissues. The beta1-adrenoceptor agonist, dobutamine, produced relaxation of rat ureter. The beta2-adrenoceptor agonist, procaterol, produced more significant relaxation of rabbit ureter than did dobutamine. CL-316243 [(R,R)-5-[2-[[2-(3-chlorophenyl)-2-hydroxyethylamino]propyl]-1,3-b enzodioxole-2,2-dicarboxylate] and CGP-12177A [(+/-)[4-[3[(1,1-dimethylethyl)amino]-2-hydroxypropoxy]-1,3-dihydro-2H-+ ++benzimidazol-2-one hydrochloride], beta3-adrenoceptor agonists, were more effective in relaxing canine ureter than were dobutamine and procaterol. Isoprenaline-induced relaxation was antagonized by a beta1-adrenoceptor antagonist, CGP-20712A [2-hydroxy-5(2-((2-hydroxy-3-(4-((1-methyl-4-trifluoromethyl)1H-imidazol e-2-yl)phenoxy)propyl)amino)ethoxy)-benzamide monomethane sulphonate], in rats and by a beta2-adrenoceptor antagonist, ICI-118,551 [(+/-)-1-[(2,3-dihydro-7-methyl- 1H-inden-4-yl)oxy]-3-[(1-methylethyl)amino]-2-butanol hydrochloride], in rabbits. The non-selective beta-adrenoceptor antagonist, bupranolol, antagonized isoprenaline-induced relaxation in all species tested. In conclusion, beta-adrenoceptor agonists may relax ureter by stimulating mainly beta1-adrenoceptors in rats, beta2-adrenoceptors in rabbits and mainly beta3-adrenoceptors in dogs.

Distribution and functional effects of neuropeptide Y on equine ureteral smooth muscle and resistance arteries

The distribution of neuropeptide Y (NPY)-immunoreactive (IR) nerves, as well as the functional effects of NPY and the Y1- and Y2-receptor agonists, [Leu31,Pro34]NPY and NPY(13-36), respectively, have been investigated in vitro in both visceral and arterial smooth muscle of the horse intravesical ureter. NPY-IR nerve fibres were widely distributed along the entire length of the ureter, although the intravesical part was the most richly innervated region, and the only one where NPY-IR ganglion cells were found. NPY (10(-7) M) did not affect either basal tone or spontaneous rhythmic contractions of the isolated intravesical ureter, but significantly enhanced the increases in both tone and frequency of phasic activity elicited by noradrenaline (10(-6) and 10(-5) M). The Y1-receptor agonist, [Leu31,Pro34]NPY (10(-7) and 10(-6) M) did not significantly alter either ureteral basal tone or the contractile activity induced by noradrenaline, whereas the Y2-receptor agonist, NPY(13-36) (10(-7) M), mimicked the potentiating effect of NPY on noradrenaline responses. In ureteral resistance arteries (effective lumen diameters of 130-300 microm), NPY (10(-10) to 10(-7) M) elicited concentration-dependent contractions, which were inversely correlated with the arterial lumen diameter. Submaximal concentrations of NPY (10(-8) M) significantly increased the sensitivity of ureteral arteries to noradrenaline. [Leu31,Pro34]NPY (10(-10) to 10(-7) M), but not NPY(13-36), induced a contractile effect of similar magnitude and potency as those of NPY, and also potentiated noradrenaline responses. The present results demonstrate a rich NPY-innervation in the intravesical ureter and reveal functional effects of the peptide enhancing motor activity in both ureteral and arterial smooth muscles, although the receptors mediating such effects seem to be different. Thus, NPY potentiates the phasic contractions and tone elicited by noradrenaline through Y2-receptors, whereas it both contracts and potentiates noradrenaline vasoconstriction in ureteral arteries via Y1-receptors.

Involvement of a glibenclamide-sensitive mechanism in the nitrergic neurotransmission of the pig intravesical ureter

1. The present study was designed to investigate whether potassium (K+) channels are involved in the relaxations to nitric oxide (NO) of pig intravesical ureteral preparations suspended in organ baths for isometric tension recordings. In ureteral strips treated with guanethidine (10(-5) M) and atropine (10(-7) M) to block adrenergic neurotransmission and muscarinic receptors, respectively, NO was either released from nitrergic nerves by electrical field stimulation (EFS, 0.5-10 Hz., 1 ms duration, 20 s trains), or exogenously-applied as an acidified solution of sodium nitrite (NaNO2, 10(-6)-10(-3) M). 2. Incubation with an inhibitor of guanylate cyclase activation by NO, methylene blue (10(-5) M) did not change the basal tension of intravesical ureteral strips but inhibited the relaxation induced by EFS or exogenous NO on ureteral preparations contracted with the thromboxane analogue U46619 (10(-7) M). 3. Incubation with charybdotoxin (3 x 10(-8) M) and apamin (5 x 10(-7) M), which are inhibitors of large and small conductance calcium (Ca2+)-activated K+ channels, respectively, did not modify basal tension or the relaxations induced by EFS and exogenous NO. Treatment with charybdotoxin or apamin plus methylene blue (10(-5) M) significantly reduced the relaxations to EFS and exogenous NO. However, in both cases the reductions were similar to the inhibition evoked by methylene blue alone. The combined addition of charybdotoxin plus apamin did not change the relaxations to EFS or exogenously added NO of the porcine intravesical ureter. 4. Cromakalim (10(-8) 3 x 10(-6) M), an opener of ATP-sensitive K+ channels, evoked a dose-dependent relaxation with a pD2 of 7.3 +/- 0.2 and maximum relaxant effect of a 71.8 +/- 4.2% of the contraction induced by U46619 in the pig intravesical ureter. The blocker of ATP-sensitive K+ channels, glibenclamide (10(-6) M), inhibited markedly the relaxations to cromakalim. 5. Glibenclamide (10(-6) M) had no effect on the basal tone of ureteral preparations but significantly reduced the relaxations induced by both EFS and exogenous NO. Combined treatment with methylene blue (10(-5) M) and glibenclamide (10(-6) M) did not exert an effect greater than that of methylene blue alone on either EFS- or NO-evoked relaxations of the pig ureter. 6. The present results suggest that NO acts as an inhibitory neurotransmitter in the pig intravesical ureter and relaxes smooth muscle through a guanylate cyclase-dependent mechanism which seems to favour the opening of glibenclamide-sensitive K+ channels.