Colocalization of nitric oxide synthase with vasoactive intestinal peptide, neuropeptide Y, and tyrosine hydroxylase in nerves supplying the human ureter

Comparison of the Efficacy of Male Sexual Activity Versus Alpha-Blockers in the Expulsion of Distal Ureteric Stones: A Systematic Review and Meta-Analysis

Globally, the prevalence of urolithiasis is increasing, with limited effective treatment options. Though debate exists within the literature, the use of medical expulsive therapy (MET) for distal ureteric stones in the form of alpha-blockers is commonplace. Alpha-blockers work via the inhibition of norepinephrine, resulting in a small degree of distal ureteric relaxation. Nitric oxide (NO), the main neurotransmitter involved in penile erection, causes smooth muscle relaxation of the distal ureter. It is hypothesised that these alternative pathways may achieve the same desire clinical effect. To our knowledge, this is the first meta-analysis comparing the efficacy of male sexual activity, in the form of intercourse or masturbation, to alpha-blockers in the expulsion of ureteric stones. We conducted a comprehensive search of electronic databases (PubMed, MEDLINE, EMBASE, SCOPUS, CENTRAL and Google Scholar), identifying studies comparing male sexual activity versus alpha-blockers, in male patients with distal ureteric stones. The Cochrane risk-of-bias tool was used to assess the included studies. For data analysis, a random effects model was used in the event of significant heterogeneity (>75%), with fixed-effects modelling in the event of low-moderate heterogeneity. A search of electronic databases found three randomised control trials (RCTs), enrolling a total of 262 patients. There was no statistically significant difference observed when patients engaged in sexual activity rather than alpha-blocker, when looking at stone expulsion rate at two weeks (P=0.36), expulsion rate at four weeks (P=0.57), or the mean stone expulsion time (P=0.21). Furthermore, there was no significant difference observed when looking at analgesic requirements (P=0.43), or the requirement for additional procedures (P=0.57). Our meta-analysis demonstrated that male sexual activity as an alternative therapy for distal ureteric stones had comparable outcomes to the use of alpha-blocker, proving a viable alternative therapy in those patients wishing to avoid pharmacological management.

Meta-analysis of the efficacy of sexual intercourse for distal ureteric stones

OBJECTIVE

This meta-analysis was performed to evaluate the efficacy of sexual intercourse for treatment of distal ureteral stones.

METHODS

Randomized controlled trials (RCTs) of sexual intercourse for treatment of distal ureteral stones were searched using PubMed, EMBASE, and the Cochrane Controlled Trials Register.

RESULTS

Three RCTs comprising 240 patients were included in the meta-analysis, which showed that sexual intercourse was effective in treating distal ureteral stones. The expulsion rate of distal ureteral stones at the second week (odds ratio [OR] = 6.61, 95% confidence interval [CI]: 3.66 to 11.94), expulsion rate of distal ureteral stones at the fourth week (OR = 4.00, 95% CI: 2.09 to 7.64), and number of analgesic injections (mean difference [MD] = -0.79, 95% CI: -1.51 to -0.08) indicated that sexual intercourse was more effective than placebo. However, the mean expulsion time of distal ureteral stones (MD = -3.98, 95% CI: -8.77 to 0.81) showed no difference between sexual intercourse and placebo.

CONCLUSIONS

Compared with placebo, sexual intercourse exhibited greater efficacy for the treatment of distal ureteral stones, whilst potentially alleviating pain.

The Role of Nitric Oxide and Hydrogen Sulfide in Urinary Tract Function

This MiniReview focuses on the role played by nitric oxide (NO) and hydrogen sulfide (H₂ S) in physiology of the upper and lower urinary tract. NO and H₂ S, together with carbon monoxide, belong to the group of gaseous autocrine/paracrine messengers or gasotransmitters, which are employed for intra- and intercellular communication in almost all organ systems. Because they are lipid-soluble gases, gaseous transmitters are not constrained by cellular membranes, so that their storage in vesicles for later release is not possible. Gasotransmitter signals are terminated by falling concentrations upon reduction in production that are caused by reacting with cellular components (essentially reactive oxygen species and NO), binding to cellular components or diffusing away. NO and, more recently, H₂ S have been identified as key mediators in neurotransmission of the urinary tract, involved in the regulation of ureteral smooth muscle activity and urinary flow ureteral resistance, as well as by playing a crucial role in the smooth muscle relaxation of bladder outlet region. Urinary bladder function is also dependent on integration of inhibitory mediators, such as NO, released from the urothelium. In the bladder base and distal ureter, the co-localization of neuronal NO synthase with substance P and calcitonin gene-related peptide in sensory nerves as well as the existence of a high nicotinamide adenine dinucleotide phosphate-diaphorase activity in dorsal root ganglion neurons also suggests the involvement of NO as a sensory neurotransmitter.

Therapeutic concentrations of valproate but not amitriptyline increase neuropeptide Y (NPY) expression in the human SH-SY5Y neuroblastoma cell line

Neuropeptide Y (NPY) is a peptide found in the brain and autonomic nervous system, which is associated with anxiety, depression, epilepsy, learning and memory, sleep, obesity and circadian rhythms. NPY has recently gained much attention as an endogenous antiepileptic and antidepressant agent, as drugs with antiepileptic and/or mood-stabilizing properties may exert their action by increasing NPY concentrations, which in turn can reduce anxiety and depression levels, dampen seizures or increase seizure threshold. We have used human neuroblastoma SH-SY5Y cells to investigate the effect of valproate (VPA) and amitriptyline (AMI) on NPY expression at therapeutic plasma concentrations of 0.6mM and 630nM, respectively. In addition, 12-O-tetradecanoylphorbol-13-acetate (TPA) known to differentiate SH-SY5Y cells into a neuronal phenotype and to increase NPY expression through activation of protein kinase C (PKC) was applied as a positive control (16nM). Cell viability after drug treatment was tested with a 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. NPY expression was measured using immunofluorescence and quantitative RT-PCR (qRT-PCR). Results from immunocytochemistry have shown NPY levels to be significantly increased following a 72h but not 24h VPA treatment. A further increase in expression was observed with simultaneous VPA and TPA treatment, suggesting that the two agents may increase NPY expression through different mechanisms. The increase in NPY mRNA by VPA and TPA was confirmed with qRT-PCR after 72h. In contrast, AMI had no effect on NPY expression in SH-SY5Y cells. Together, the data point to an elevation of human NPY mRNA and peptide levels by therapeutic concentrations of VPA following chronic treatment. Thus, upregulation of NPY may have an impact in anti-cancer treatment of neuroblastomas with VPA, and antagonizing hypothalamic NPY effects may help to ameliorate VPA-induced weight gain and obesity without interfering with the desired central effects of VPA.

Cyclic nucleotide metabolism including nitric oxide and phosphodiesterase-related targets in the lower urinary tract

The clinical data on the use of the orally active phosphodiesterase (PDE) type 5 inhibitors sildenafil (VIAGRA™), vardenafil (LEVITRA™), and tadalafil (CIALIS™) for the treatment of male erectile dysfunction have boosted research activities on the physiology and pharmacology of the organs of the lower urinary tract (LUT). This includes both intracellular signal transduction in the prostate, urinary bladder (detrusor), and urethra, as well as central brain and spinal cord pathways controlling the function of the LUT. Such efforts provided the basis for the development of new therapeutic modalities into the management of dysfunctions/ syndromes of the LUT, some of which are already offered to the patients. The pharmacological treatment of the overactive bladder and the so-called benign prostatic syndrome, including LUT symptomatology and bladder outlet obstruction secondary to benign prostatic enlargement, has primarily focused on selective, orally available drugs acting by influencing intracellular regulatory mechanisms. These agents are regarded efficacious, have a fast onset of drug action in the target tissue and an improved effect-to-side-effect ratio. Better understanding of the functional significance of proteins related to cyclic nucleotide-dependent pathways, such as nitric oxide synthase, cytosolic and membrane-bound guanylyl cyclases, PDE isoenzymes and cyclic AMP- and cyclic GMP-binding protein kinases, the relative distribution in tissues of the LUT, and the consequences for urogenital function, seems to be of particular interest in order to identify new or more selective pharmacological approaches to manage disorders of the LUT. The present review focuses on cyclic nucleotide-related targets involved in the control of the function of the bladder, prostate, and urethra and the significance of those proteins in the process of evolving new pharmacological options for the treatment of LUT symptoms secondary to benign prostatic hyperplasia as well as dysfunctions of the storage and voiding capability of the urinary bladder.

Treatment of erectile dysfunction and lower urinary tract symptoms by phosphodiesterase inhibitors

To date, it is widely accepted that several disorders of the male and female urogenital tract, such as erectile dysfunction, bladder overactivity, urinary stone disease, the benign prostatic syndrome, as well as symptoms of female sexual arousal and orgasmic dysfunctions, can be therapeutically approached by influencing the function of the smooth musculature of the respective organs. To achieve a pronounced drug effect without significant adverse events, a certain degree of tissue selectivity is mandatory. Selective intervention in intracellular pathways regulating smooth muscle tone has become the most promising strategy to modulate tissue and organ function. Since the concept of taking a pill to relieve symptoms of lower urinary tract dysfunction is now widely accepted following the successes of phosphodiesterase 5 (PDE5) inhibitor treatment of erectile dysfunction, the treatment of urological diseases has focused on orally available drugs acting via influencing intracellular signaling pathways, thereby combining a high response rate with the advantage of an on-demand intake. Specifically, the use of isoenzyme-selective PDE inhibitors offers great opportunities in the medical treatment of various genitourinary diseases. These agents are regarded to be safe and to be efficacious, i.e., having a fast onset of drug action and an improved effect-to-side-effect ratio. As experience with this class of compounds and their use in urology is rapidly growing, basic and clinical research in this field will most likely expand the pharmacological armamentarium of innovative treatment options in the next few years. The purpose of this review is to summarize current, as well as potential, upcoming indications for the use of PDE inhibitors in the pharmacotherapy of male erectile dysfunction and lower urinary tract symptoms.

Autonomic control of the urogenital tract

The urogenital tract houses many of the organs that play a major role in homeostasis, in particular those that control water and salt balance, and reproductive function. This review focuses on the anatomical and functional innervation of the kidneys, urinary ducts and bladders of the urinary system, and the gonads, gonadal ducts, and intromittent organs of the reproductive tract. The literature, especially in recent years, is overwhelmingly skewed toward the situation in mammals. Nevertheless, where specific neurochemical markers have been investigated, common patterns of innervation can be found in representatives from most vertebrate classes. Not surprisingly the vasculature, epithelia and smooth muscle of all urogenital organs receives adrenergic innervation. These nerves may contain non-adrenergic non-cholinergic (NANC) neurotransmitters such as ATP and NPY. Cholinergic nerves increase motility in most urogenital organs with the exception of the kidney. The major NANC nerves found to influence urogenital organs include those containing VIP/PACAP, galanin and neuronal nitric oxide synthase. These can be found associated with both smooth muscle and epithelia. The role these nerves play, and the circumstances where they are activated are for the most part unknown.

Demonstration of intrinsic innervation of the guinea pig upper urinary tract using whole-mount preparation

AIMS

The morphology and functional importance of the autonomic nervous system in the upper urinary tract is still not completely understood. Previous histological studies investigating the innervation of the urinary tract have mainly used conventional sections in which the three-dimensional structure of the intramural innervation is difficult to achieve. In contrast, the whole-mount preparation technique is a suitable method for visualizing the distribution of the mesh-like neuronal networks within the urinary tract.

METHODS

The distribution and regional variation of neurofilament (NF), tyrosine hydroxylase (TH), choline acetyltransferase (ChAT), and substance P-immunoreactive (SP-IR) neurons, as well as acetylcholinesterase (AChE) and nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d)-positive neurons were investigated using whole-mount preparations of the guinea pig upper urinary tract.

RESULTS

Two distinct nervous plexuses were detected within the muscle layers containing NF, TH, ChAT, and SP-IR nerves. AChE-positive nerves were seen in all layers. Only moderate NADPH-d-positive innervation was found. Renal pelvis, upper and lower part of the ureter showed an overall increased innervation compared to the middle portion of the ureter. Ganglia were found at the pelviureteric border displaying NF and TH immunoreactivity.

CONCLUSION

The whole-mount preparation technique provides an elegant method for assessing the three-dimensional architecture of ureteral innervation. The guinea pig upper urinary tract is richly supplied with adrenergic, cholinergic, nitrergic, and sensory nerves which suggest that the autonomous nervous system plays an important role in controlling ureteral motility and blood flow.

Doxazosin for the management of distal-ureteral stones

PURPOSE

To evaluate the efficacy of doxazosin in inducing spontaneous passage of stones in the distal ureter and to compare its efficacy according to the size of the stone.

PATIENTS AND METHODS

Seventy-three patients with a mean age of 46.38 +/- 10.17 years who presented with a distal-ureteral stone were divided into four groups according to stone size and drug treatment: <5 mm without doxazosin (group A; n=15); 5-10 mm (group B; n=16); <5 mm with doxazosin 4 mg/day for 4 weeks (group C; n=20); and 5-10 mm with doxazosin 4 mg/day for 4 weeks (group D; n=22). Groups A and B served as controls for groups C and D, respectively.

RESULTS

Spontaneous stone passage was documented in 9 patients (60%) in group A v 17 (85%) in group C (P=0.047) and 7 (43.75%) in group B v 16 (72.73%) in group D (P=0.036). The average expulsion time was 8.78 +/- 1.09 days in group A v 7.59 +/- 0.80 days in group C (P=0.004) and 12.14 +/- 1.35 days in group B v 7.06 +/- 1.29 days in group D (P<0.0001). The number of pain episodes in group D patients was significantly lower than in group B (P +/- 0.0078).

CONCLUSIONS

Doxazosin treatment proved to be safe and effective for distal-ureteral stones, as determined by earlier expulsion, decreased colic frequency, and absence of side effects. The efficacy of doxazosin was significantly higher for 5-to 10-mm stones than for smaller ones.

Neuronal and smooth muscle receptors involved in the PACAP- and VIP-induced relaxations of the pig urinary bladder neck

BACKGROUND AND PURPOSE

As pituitary adenylate cyclase-activating polypeptide 38 (PACAP 38)- and vasoactive intestinal peptide (VIP) are widely distributed in the urinary tract, the current study investigated the receptors and mechanisms involved in relaxations induced by these peptides in the pig bladder neck.

EXPERIMENTAL APPROACH

Urothelium-denuded strips were suspended in organ baths for isometric force recordings and the relaxations to VIP and PACAP analogues were investigated.

KEY RESULTS

VIP, PACAP 38, PACAP 27 and [Ala(11,22,28)]-VIP produced similar relaxations. Inhibition of neuronal voltage-gated Ca(2+) channels reduced relaxations to PACAP 38 and increased those induced by VIP. Blockade of capsaicin-sensitive primary afferents (CSPA), nitric oxide (NO)-synthase or guanylate cyclase reduced the PACAP 38 relaxations but failed to modify the VIP responses. Inhibition of VIP/PACAP receptors and of voltage-gated K(+) channels reduced PACAP 38 and VIP relaxations, which were not modified by the K(+) channel blockers iberiotoxin, charybdotoxin, apamin or glibenclamide. The phosphodiesterase 4 inhibitor rolipram and the adenylate cyclase activator forskolin produced potent relaxations. Blockade of protein kinase A (PKA) reduced PACAP 38- and VIP-induced relaxations.

CONCLUSIONS AND IMPLICATIONS

PACAP 38 and VIP relax the pig urinary bladder neck through muscle VPAC(2) receptors linked to the cAMP-PKA pathway and involve activation of voltage-gated K(+) channels. Facilitatory PAC(1) receptors located at CSPA and coupled to NO release, and inhibitory VPAC receptors at motor endings are also involved in the relaxations to PACAP 38 and VIP, respectively. VIP/PACAP receptor antagonists could be useful in the therapy of urinary incontinence produced by intrinsic sphincter deficiency.

Interindividual Variation in Distribution of Extramural Ganglion Cells in the Male Pelvis: A Semi-Quantitative and Immunohistochemical Study Concerning Nerve-Sparing Pelvic Surgery

OBJECTIVE

We examined distribution and numbers of extramural ganglion cells in the male pelvis, classifying them as sympathetic or parasympathetic.

METHODS

Specimens were obtained from 14 formalin-fixed donated male cadavers. Semiserial sections were processed for histologic examination, and for immunohistochemistry using anti-tyrosine hydroxylase (TH) or anti-peptide histidine isoleucine (PHI).

RESULTS

Like those along the sacral sympathetic trunk, most other pelvic ganglion cells were located in and along nerve components. Yet the ganglion cell clusters attached to pelvic viscera accounted for 22% to 38% of ganglion cells. These were seen at the dorsal aspect of the bladder, the bladder/prostate junction, the dorsal aspect of the seminal vesicle, and along the prostate, but not along the extrapelvic pudendal nerve, cavernous tissues including the penile hilum, the rhabdosphincter, retropubic fat or recto-urethral muscle. Two fold interindividual variation was seen for total ganglion cell number (3044 to 6522) in the pelvis. TH-positive and PHI-positive cells intermingled at various ratio in every ganglion cell cluster. Sympathetic TH-positive proportions tended to be site-specific.

CONCLUSIONS

Pelvic autonomic cells exist not only in nerve components but also along viscera. Even nerve-sparing radical prostatectomy can compromise visceral ganglia. Simple classification of pelvic nerve components as sympathetic or parasympathetic would seem misleading given coexistence of both cell types in a ganglion.

Pharmacology of the lower urinary tract: basis for current and future treatments of urinary incontinence

The lower urinary tract constitutes a functional unit controlled by a complex interplay between the central and peripheral nervous systems and local regulatory factors. In the adult, micturition is controlled by a spinobulbospinal reflex, which is under suprapontine control. Several central nervous system transmitters can modulate voiding, as well as, potentially, drugs affecting voiding; for example, noradrenaline, GABA, or dopamine receptors and mechanisms may be therapeutically useful. Peripherally, lower urinary tract function is dependent on the concerted action of the smooth and striated muscles of the urinary bladder, urethra, and periurethral region. Various neurotransmitters, including acetylcholine, noradrenaline, adenosine triphosphate, nitric oxide, and neuropeptides, have been implicated in this neural regulation. Muscarinic receptors mediate normal bladder contraction as well as at least the main part of contraction in the overactive bladder. Disorders of micturition can roughly be classified as disturbances of storage or disturbances of emptying. Failure to store urine may lead to various forms of incontinence, the main forms of which are urge and stress incontinence. The etiology and pathophysiology of these disorders remain incompletely known, which is reflected in the fact that current drug treatment includes a relatively small number of more or less well-documented alternatives. Antimuscarinics are the main-stay of pharmacological treatment of the overactive bladder syndrome, which is characterized by urgency, frequency, and urge incontinence. Accepted drug treatments of stress incontinence are currently scarce, but new alternatives are emerging. New targets for control of micturition are being defined, but further research is needed to advance the pharmacological treatment of micturition disorders.

Oral nitric oxide donors: a new pharmacological approach to detrusor-sphincter dyssynergia in spinal cord injured patients?

PURPOSE

Detrusor-sphincter dyssynergia is a common cause of bladder outlet obstruction in spinal cord injured patients and leads to poor bladder emptying and high bladder pressures, which if left untreated might cause renal failure. In this study, we tested the recently published hypothesis that oral administration of a nitric oxide donor could be a new pharmacological approach to treat detrusor-sphincter dyssynergia in humans with spinal cord injury.

METHODS

12 male spinal cord injured patients presenting with neurogenic detrusor overactivity and detrusor-sphincter dyssynergia were studied. 6 performed clean intermittent catheterisation and 6 used suprapubic tapping for bladder emptying. During cystometry the bladder was filled until the first overactive bladder contraction accompanied by detrusor-sphincter dyssynergia occurred while bladder and external urethral sphincter pressures were continuously recorded. Then the bladder was emptied and the patients received 10 mg of isosorbide dinitrate sublingually. Resting pressures were recorded and cystometry was repeated starting 15 min after drug administration. Maximal and mean values for bladder and external urethral sphincter pressures were calculated in both fillings and statistically compared by analysis of variance for repeated measurements (level of significance p < 0.05).

RESULTS

Nitric oxide significantly reduced external urethral sphincter pressures at rest (p < 0.05) and during dyssynergic contraction (p < 0.05) while bladder pressures at rest and during contraction as well as the reflex volume remained unchanged. In the patients who used suprapubic tapping for bladder emptying the mean post triggering residual volume was significantly reduced (p < 0.05).

CONCLUSIONS

Oral administration of nitric oxide donors significantly reduced bladder outlet obstruction due to detrusor-sphincter dyssynergia suggesting a role for nitric oxide in inhibitory neurotransmission to the urethral sphincter. This new approach could offer a potential pharmacological option to treat detrusor-sphincter dyssynergia in spinal cord injured patients.

The effect of nitric oxide on the resting tone and the contractile behaviour of the external urethral sphincter: a functional urodynamic study in healthy humans

AIMS

This functional urodynamic study assessed the effect of the nitric oxide donor isosorbide dinitrate on the external urethral sphincter and hypothesised first that nitric oxide could lower the resting sphincter pressure, second that nitric oxide could influence the sphincter contractility during magnetic stimulation, and third that nitric oxide could induce a faster external urethral sphincter fatigue during continuous magnetic stimulation.

METHODS

Eight healthy males gave their written informed consent and were included. A 2-channel microtip pressure transducer catheter was inserted into the urethra measuring the bladder and the external urethral sphincter pressure. Magnetic stimulation of the sacral roots was performed to evoke reproducible contractions of the external urethral sphincter. The baseline protocol included six single pulse stimulations and three stimulations 10sec in duration each for two frequencies 5Hz and 50Hz with intensities at the motor threshold of the pelvic floor. Then the subjects received 10 mg of isosorbide nitrate sublingually and the protocol was repeated 5min, 20min, 40min and 60min after drug administration.

RESULTS

The sublingual administration of isosorbide dinitrate could significantly reduce the resting pressure of the external urethral sphincter for at least one hour. The maximal contractile strength measured as the maximal urethral pressure during single pulse and continuous magnetic stimulation of the sacral roots also decreased significantly. Nitric oxide did not induce a significantly faster fatigue of the external urethral sphincter during continuous magnetic stimulation of the sacral roots.

CONCLUSIONS

This study shows a functionally relevant effect of nitric oxide on the resting tone and the contractile behaviour of the human external urethral sphincter in vivo while the fatigue properties did not changed significantly. Nitric oxide donors could offer a new pharmacological approach to treat urinary retention due to overactive or non-relaxing external urethral sphincter.

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.

Differing effects of N(G)-monomethyl L-arginine and 7-nitroindazole on detrusor activity

AIMS

Previous studies reported that nitric oxide (NO) synthase (NOS) inhibition decreases micturition volume threshold (MVT), the volume required to produce a centrally mediated micturition contraction, and that NO can be released from urothelium by means of certain stimuli. With elucidation of multiple isoforms of NOS, studies were performed to determine whether inhibition of specific isoforms of NOS altered MVT in different ways.

METHODS

In naive, anesthetized cats, the urinary bladder was exposed by means of a midline abdominal incision and cannulated through a slit in the internal urethra approximately 4-5 cm distal to the neck of the bladder. The left renal artery and left radial vein were cannulated for the intra-arterial and intravenous administration of drugs, respectively. All nerves were left intact. A control MVT was determined by slowly infusing saline into the bladder at a rate of 0.018 mL/kg per minute. Varying doses of L-NMMA (N(G)-monomethyl-L-arginine) or 7-NI (7-nitro indazole) were administered and the MVT was again determined.

RESULTS

Inhibition of endothelial NOS (eNOS), by L-NMMA, or neuronal NOS (nNOS), by 7-NI, produces varying effects on certain detrusor activities and that inhibition of different isoforms of NOS produces qualitatively different effects. L-NMMA significantly decreases MVT (up to 60% decrease), whereas 7-NI significantly increases MVT (over 300% increase). L-NMMA increases frequency and onset of small bladder contractions, whereas 7-NI produces opposite effects.

CONCLUSIONS

The results suggest that detrusor relaxation and contractility may be modulated by NO levels and that NO released from the urothelium may be a mediator of detrusor relaxation during the storage phase of micturition.

Innervation of congenitally hydronephrotic and normal porcine upper urinary tract

OBJECTIVE

To investigate the intrinsic innervation of the upper urinary tract in congenitally hydronephrotic and normal Goettingen minipigs, using the whole-mount preparation technique.

MATERIALS AND METHODS

Whole-mount preparations of hydronephrotic (two with bilateral ectopic ureters, one with left distal ureteric stenosis) and normal (three) porcine upper urinary tracts were examined by immunohistochemistry with tyrosine hydroxylase (TH) and neurofilament and by histochemical staining with NADPH-diaphorase and acetylcholinesterase. Staining results were evaluated using normal bright-field and confocal laser scanning microscopy.

RESULTS

Neurofilament-, TH-immunoreactive and acetylcholinesterase-positive nerve fibres and neuronal networks were identified in the adventitial, muscle and subepithelial layers of the whole upper urinary tract. An NADPH-diaphorase-positive network was expressed in the subepithelial layer and less densely in the muscle layer. The general distribution of the identified neuronal networks was similar in hydronephrotic and normal upper urinary tracts, but the density of these neuronal networks was less in the former. The most striking observation was the absence or marked reduction of neuronal networks in the stenotic part of the ureter in the pig with left distal ureteric stenosis.

CONCLUSION

Whole-mount preparations provide a method for assessing the three-dimensional topography of neuronal networks in the different layers of the porcine upper urinary tract. Although the macroscopic differences between the hydronephrotic and normal porcine upper urinary tracts were striking, changes in the innervation pattern were less obvious, except in distal ureteric stenosis.

Use of glyceryl trinitrate patches in patients with ureteral stones: a randomized, double-blind, placebo-controlled study

OBJECTIVES

To report a randomized, double-blind, placebo-controlled trial of glyceryl trinitrate (GTN) patches. The primary outcome measure was stone passage at 6 weeks. GTN is a potent smooth muscle relaxant that may offer benefit by both reducing pain and facilitating ureteral stone passage.

METHODS

Fifty consecutive patients, with a single radiopaque calculus less than 10 mm, were randomized to receive a 6-week course of patches containing either 5 mg GTN or placebo. Patients used a diary to record pain episodes during the 6-week study period and were reviewed weekly with x-ray imaging. Analysis was by intention to treat.

RESULTS

Twenty-six patients were randomized to the GTN group and 24 to the placebo group. Seven patients in the GTN group discontinued therapy because of headaches. One patient in the placebo group discontinued because of a skin reaction to the patches. No serious adverse events were recorded. No difference was observed in the stone-free rate at 6 weeks (18 patients in each group), interval to stone passage (median GTN 11.5 days versus placebo 13 days), or interventions performed (5 patients each). Although the GTN group reported fewer pain episodes (median 3.5 versus 6.0), this did not achieve statistical significance.

CONCLUSIONS

Our preliminary results did not demonstrate a significant advantage in using GTN compared with placebo, with regard to the stone-free rate at 6 weeks, interval to stone passage, or number of episodes of pain experienced.

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.

Lack of neuropeptide Y receptor detection in human bladder and prostate

OBJECTIVE

To investigate the presence of functional neuropeptide Y (NPY) receptors in human bladder and prostate (both richly endowed with NPY-containing nerve fibers) using peptide YY (PYY) as the agonist. Materials and methods Binding studies were conducted using [125I]PYY as the radioligand. Organ-bath studies were performed on isolated tissue strips for direct (postjunctional) contractile effects and for (prejunctional) inhibition of field stimulation effects. Any possible degradation of PYY was determined using high-performance liquid chromatography (HPLC).

RESULTS

In the radioligand binding studies no quantifiable specific [125I]PYY binding was detected in human bladder or prostate, while specific high-affinity binding was readily seen in rat cerebral cortex. In organ-bath experiments, PYY (up to 1 micromol/L) caused no contraction of human prostate or bladder, whereas noradrenaline and carbachol, respectively, were effective; the potency or efficacy of noradrenaline and carbachol were not altered by PYY. Field stimulation-induced contraction was not affected by PYY in either human bladder or prostate, but was readily inhibited in rat vas deferens. HPLC detected no relevant PYY degradation by human bladder or prostate homogenates.

CONCLUSION

Human bladder and prostate express only very few if any functional NPY receptors.

The nitric oxide pathway in pig isolated calyceal smooth muscle

In pig and humans, whose kidneys have a multi-calyceal collecting system, the initiation of ureteral peristalsis takes place in the renal calyces. In the pig and human ureter, recent evidence suggests that nitric oxide (NO) is an inhibitory mediator that may be involved in the regulation of peristalsis. This study was designed to assess whether the NO synthase/NO/cyclic GMP pathway modulates the motility of pig isolated calyceal smooth muscle. Immunohistochemistry revealed a moderate overall innervation of the smooth muscle layer, and no neuronal or inducible NO synthase (NOS) immunoreactivities. Endothelial NOS immunoreactivities were observed in the urothelium and vascular endothelium, and numerous cyclic GMP-immunoreactive (-IR) calyceal smooth muscle cells were found. As measured by monitoring the conversion of L-arginine to L-citrulline, Ca(2+)-dependent NOS activity was moderate. Assessment of functional effects was performed in tissue baths and showed that NO and SIN-1 decreased spontaneous and induced contractions of isolated preparations in a concentration-dependent manner. In strips exposed to NO, there was a 10-fold increase of the cyclic GMP levels compared with control preparations (P < 0.01). It is concluded that a non-neuronal NOS/NO/cyclic GMP pathway is present in pig calyces, where it may influence motility. The demonstration of cyclic GMP-IR smooth muscle cells suggests that NO acts directly on these cells. This NOS/NO/cyclic GMP pathway may be a target for drugs inhibiting peristalsis of mammalian upper urinary tract. Neurourol. Urodynam. 18:673-685, 1999.

Immunohistochemical detection of neuronal plexuses and nerve cells within the upper urinary tract of pigs

OBJECTIVE

To investigate the distribution and topography of nervous structures within the renal pelvis and upper part of the ureter of pigs, and thus help to determine the origin, propagation and mechanisms of the modulation of pelvi-ureteric peristalsis.

MATERIALS AND METHODS

Whole-mount preparations of renal pelves from adult pigs were stained using a universal immunostaining method with streptavidin-alkaline phosphatase. Anti-neuron-specific enolase antibody and anti-neurofilament antibody were used as neuronal markers.

RESULTS

The patterns of neuronal structures differed between the renal calyces, renal pelvis and upper ureter. In the calyx, there was one single dense nerve plexus; this network contained relatively thin nerve fibres running both circularly and longitudinally. In the wall of the renal pelvis and upper ureter there were two neuronal plexuses, one submucosal and another within the muscular layer; these nerve fibres were mainly orientated longitudinally. Some single nerve cells were also found at the pelvicalyceal border.

CONCLUSIONS

These findings suggest a potent nervous system within the upper urinary tract of pigs that connects the renal calyces with the renal pelvis, pelvi-ureteric junction and ureter. The presence of these dense neuronal networks and nerve cells within the wall of the renal pelvis and ureter suggests that propagation, coordination and modulation of pelvi-ureteric peristalsis in pigs may arise through intrinsic nervous stimulation.

Neuronal nitric oxide synthase in the neural pathways of the urinary bladder

Nitric oxide (NO) is a unique biological messenger molecule. It serves, in part, as a neurotransmitter in the central and peripheral nervous systems. Neurons containing NO have been identified histochemically by the presence of nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) reactivity or immunohistochemically by the antibody for neuronal NO synthase (n-NOS). Previous histochemical or pharmacological studies have raised the possibility that NO may play an important role in the neural pathways of the lower urinary tract. There is also considerable evidence to suggest that n-NOS is plastic and could be upregulated following certain lesions in the lower urinary tract. The present review summarises the distribution of n-NOS containing neurons innervating the urinary bladder and the changes of the enzyme expression in some experimentally induced pathological conditions.

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.

Structure and autonomic innervation of the human vas deferens: a review

The motor innervation of the smooth muscle coat of the human vas deferens is predominantly noradrenergic in type while a less dense and differently distributed presumptive cholinergic innervation is also in evidence, although the precise role of the latter is undetermined. Immunohistochemical studies have confirmed the presence of catecholamine-synthesizing enzymes tyrosine hydroxylase (TH) and dopamine beta hydroxylase (DbetaH) in the majority of fine, varicose intramuscular nerves, about two-thirds of which also contain neuropeptide Y (NPY). Minor populations of noradrenergic nerves contain enkephalin (ENK), galanin (GAL), somatostatin (SOM), or nitric oxide synthase (NOS). The presumptive cholinergic intramuscular nerves contain vasoactive intestinal polypeptide (VIP) and NPY. The subepithelial nerves of the vas deferens are assumed to have a secretomotor function and are rich in acetylcholinesterase and NPY, many also containing either VIP or NOS. The muscle coat of the human vas deferens is poorly differentiated until after birth, the intramuscular nerves in the fetus being relatively thick and non-varicose. Development of a subepithelial nerve plexus lags behind that in the muscle coat but its density in the neonatal vas deferens resembles that seen in the adult. Observations on specimens of human vas deferens obtained at vasovasostomy carried out 1 to 15 years after vasectomy have shown a marked reduction in the density of noradrenergic nerves in the muscle coat of the testicular portion while that in the urethral portion remains unaltered. Furthermore, the subepithelial secretomotor nerves degenerate in the testicular portion. These long-term changes in the pattern of innervation of the vas deferens consequent upon vasectomy may have profound effects upon the outcome of vasovasostomy with respect to subsequent sperm maturation, transport, and viability.

Nitric oxide and the non-adrenergic non-cholinergic neurotransmission

In the early 1960s, the first evidence was reported demonstrating neurally mediated responses in the presence of adrenergic and cholinergic antagonists, leading to the introduction of the concept of non-adrenergic non-cholinergic neurotransmission. The inhibitory component of this part of the autonomic nervous system has been illustrated in numerous organ systems mediating a wide range of physiological events. Since the discovery of these nerves, several substances have been proposed as putative neurotransmitter, with ATP and vasoactive intestinal polypeptide as main candidates. Finally, the ongoing research on the nature of the substance released by these nerves has generated the nitrergic theory proposing nitric oxide as putative neurotransmitter. By now, increasing evidence is reported to support the idea that inhibitory neurons release more neurotransmitters, interacting with each other at pre- and/or postsynaptic levels.

Stimulation of neuropeptide Y release in rat pheochromocytoma cells by nitric oxide

Neuropeptide Y and nitric oxide (NO) synthase are colocalized in nervous tissues. We tested the hypothesis whether or not NO might be involved in the release of neuropeptide Y. Neuropeptide Y concentration in the supernatant of PC12 rat pheochromocytoma cells, shown to express NO synthase I by immunohistochemistry, rose threefold in a time- and dose-dependent manner following sodiumnitroprusside and 3-morpholinosydnonimine (SIN-1) incubation. Neuropeptide Y mRNA expression was induced by NO-donors as a function of incubation-time. Neuropeptide Y production rose fivefold with zaprinast, an inhibitor of the phosphodiesterase V and threefold with nerve growth factor (NGF). Combined application of zaprinast and NGF did not further increase neuropeptide Y production while combination of zaprinast and sodiumnitroprusside potentiated the NO effect on neuropeptide Y release. The data suggest that NO regulates neuropeptide Y secretion of PC12 pheochromocytoma cells on the mRNA level.

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.

A double-label immunohistochemical study of intramural ganglia from the human male urinary bladder neck

Double-label immunocytochemistry was used to investigate the colocalisation of various neuropeptides and the enzymes nitric oxide synthase (NOS) and tyrosine hydroxylase (TH) in intramural ganglia of the human male urinary bladder neck and trigone. Postmortem specimens were obtained from 7 male infants and children ranging in age from 2 mo to 3 y who had died as a result of cot death or accidental trauma. On average 60% of the intramural neurons were non-TH-immunoreactive (-IR) (i.e. presumptive cholinergic) and 40% were TH- and D beta H-IR (i.e. noradrenergic). Within the non-TH-IR population, calcitonin gene-related peptide (CGRP) was found in 65% of cells, neuropeptide Y (NPY) in 90%, nitric oxide synthase (NOS) in 45%, somatostatin (SOM) in 90%, and vasoactive intestinal polypeptide (VIP) in 40%. The corresponding values for the TH-IR neurons were CGRP (54%), NPY (70%), NOS (58%), SOM (73%) and VIP (40%). All the observed bombesin (BOM)-immunoreactivity was colocalised with TH while 90% of VIP and almost all the CGRP was colocalised with NPY. Less than 5% of neurons were immunoreactive for substance P (SP) or met-enkephalin (m-ENK) and some of these also contained TH. Varicose nerve fibres were seen in close proximity to some of the intramural neurons, the majority of such varicosities showing immunoreactivity to CGRP, VIP or TH. Less common were pericellular varicosities immunoreactive to NPY, SOM or SP. These results demonstrate the neurochemical heterogeneity of intramural neurons in the human bladder neck and provide indirect evidence for the complexity of the peripheral innervation of the human urinary bladder.

A possible role for nitric oxide in the regulation of human ureteral smooth muscle tone in vitro

There is ample evidence that nitric oxide (NO) is an important neurotransmitter in many tissues of the urogenital tract. The aim of the present study was to examine the possible role of NO in ureteral relaxation. Human ureteral rings were mounted in organ bath chambers and precontracted in KCl. Increasing doses of the NO donor linsidomine (SIN-1) were added with and without prior blockade of the NO/cGMP pathway by methylene blue and protein kinase (PK) inhibitors Rp-8-pCPT-cGMPS and RP-8-CPT-cAMPS. Electrical filed stimulation (EFS) was done before and after incubation with L-NOARG (NG-nitro-L-arginine) and TTX (tetratodoxin). For detection of neuronal NO synthase (NOS), ureters were stained immunohistochemically. Ureteral strips were dose dependently relaxed by SIN-1; preincubation with methylene blue and protein kinase G inhibitor significantly reduced the SIN-1-induced relaxations. No effects of L-NOARG and TTX on EFS-induced tone alterations were found. NOS-positive neuronal axons and nerve-ending-like structures were found in the muscular layers. Our in vitro findings suggest that ureteral relaxation may involve the NO pathway.

Electroureterogram: human study of the electromechanical activity of the ureter

OBJECTIVES

To study the electromechanical activity of the normal ureter in 5 men and 4 women (mean age 39.4 +/- 10.8 years) scheduled for rectopexy due to rectal prolapse. The results of urinary tract investigations were normal.

METHODS

During anesthesia for rectopexy, rectal mobilization necessitates ureteral exposure for protective reasons. One electrode was applied to each of the upper, middle, and lower third of the right ureter, and signals were registered for 30 minutes. Simultaneous recording of intraureteral pressure was performed.

RESULTS

Slow waves, or pacesetter potentials (PPs), were recorded from the three electrodes. Identical readings for frequency, amplitude, and velocity of conduction were obtained from the three electrodes in the same ureter. Action potentials (APs) followed the PPs and were inconsistent and were associated with an intraureteral pressure increase (P < 0.001). No pressure elevation occurred with PPs.

CONCLUSIONS

In contrast to PPs, APs seem to have a role in ureteral mechanical activity and might initiate ureteral peristalsis. The function of the PPs is unknown; they might pace the APs in terms of direction and frequency. The present study could characterize an electroureterographic pattern for the normal ureter. It is suggested that this pattern is changed in the various ureteral pathologic conditions and, thus, the electroureterogram be considered a useful investigative tool in ureteral disorders. However, the procedure in its present from is not applicable to clinical practice. Nevertheless, the present study might be of significance in explaining the mechanisms of ureteral motility and urinary bolus transport.

Colocalisation of NADPH-diaphorase with neuropeptides in the ureterovesical ganglia of humans

Neurones in the ureterovesical ganglion complex provide autonomic innervation to the pelvic ureter, the ureterovesical junction and the bladder trigone. We examined the distribution and peptide co-expression pattern of nitric oxide synthase (NOS) in the human ureterovesical ganglia by combining NADPH-diaphorase histochemistry with immunoreactivity for vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), and calcitonin gene-related peptide (CGRP). Less than 20% of nerve cells in the large ganglia of the ureterovesical complex were stained for NOS activity. In elderly individuals, ganglion cells regularly exhibited conspicuous morphological alterations suggestive of degenerative changes. Most of the NOS-positive cell bodies costained for VIP-immunoreactivity. A minority of NOS-expressing cells also reacted for NPY-immunoreactivity. CGRP-immunoreactivity was present in varicose terminal-like nerve fibres which were found to encircle NOS-containing perikarya. Occasionally, NOS-positive somata were surrounded by plexiform axon terminals which immunostained for VIP or NPY. We conclude that the passage of urine across the ureterovesical junction is under relaxatory control of a local nitric oxide/VIP(NPY) pathway which may be modulated by preganglionic efferent and/or primary afferent input.

Co-localisation of tyrosine hydroxylase, nitric oxide synthase and neuropeptides in neurons of the human postnatal male pelvic ganglia

Double-label immunocytochemistry was used to investigate the co-localisation of neuropeptides and the enzyme nitric oxide synthase (NOS) with tyrosine hydroxylase (TH) in autonomic ganglia of the human postnatal male pelvic plexus. Postmortem specimens were obtained from six male infants and children ranging in age from 2 to 12 months who had died as a result of cot death or accidental trauma. On average, ganglia lying adjacent to the neck of the urinary bladder contained 45% of neurons which were TH-immunoreactive (-IR) while ganglia situated adjacent to the posterior and lateral aspects of the prostate gland contained 67% of neurons which were TH-IR. All the TH-IR neurons also contained dopamine beta-hydroxylase and were considered to be noradrenergic in type. On average, 61% of TH-IR neurons in bladder ganglia contained NOS, compared with 77% of non-TH-IR neurons (based on counts of over 1,000 cells in each case), while the percentages of TH- and non-TH-IR neurons containing neuropeptides were: calcitonin gene-related peptide (CGRP) (30%; 11%), neuropeptide Y (NPY) (66%; 92%), somatostatin (SOM) (70%; 29%), substance P (SP) (64%; 46%), vasoactive intestinal polypeptide (VIP) (64%; 83%). The equivalent values for TH- and non-TH-IR neurons in prostatic ganglia were NOS (38%; 59%), CGRP (55%; 18%), NPY (62%, 65%), SOM (14%, 20%), SP (13%, 8%) and VIP (42%; 82%). Varicose nerve fibers within the ganglia were seen forming pericellular arborizations around many of the ganglion cells, the most numerous containing TH-, CGRP-, NPY-, SOM- or VIP-immunoreactivity. Less common were pericellular varicosities containing SP-immunoreactivity while terminals containing NOS were not observed. No correlation could be detected between the peptide contents of the ganglion cells and of the associated pericellular terminals. However, the peptide content of the ganglion cells found in association with the urinary bladder and prostate gland correlates well with the previously documented coexistence of enzymes and neuropeptides in the intrinsic nerve fibers supplying these two regions of the human postnatal male genitourinary system.

Characterization of nitric oxide synthase activity in sheep urinary tract: functional implications

1. To define further the role of nitric oxide (NO) in urinary tract function, we have measured the presence of nitric oxide synthase (NOS) activity, and its relationship with functional NO-mediated responses to electrical field stimulation (EFS) in the urethra, the detrusor and the ureter from sheep. NOS activity was assayed by the conversion of L-[14C]-arginine to L-[14C]-citrulline. Endogenous production of citrulline was confirmed by thin layer chromatography. 2. NOS enzymatic activity was detected in the cytosolic fraction from tissue homogenates with the following regional distribution (pmol citrulline mg-1 protein min-1): urethra (33 +/- 3.3), detrusor (13.1 +/- 1.1) and ureter (1.5 +/- 0.2). No activity was detected in the particulate fraction of any region. 3. NOS activity was dependent on Ca(2+)-calmodulin and required exogenously added NADPH and tetrahydrobyoptein (BH4) for maximal activity. Exclusion of calmodulin from the incubation mixture did not modify NOS activity, but it was significantly reduced in the presence of the calmodulin antagonist, calmidazolium, suggesting the presence of enough endogenous calmodulin to sustain the observed NOS activity. 4. NOS activity was inhibited to a greater extent by NG-nitro-L-arginine (L-NOARG) and its methyl ester (L-NAME) than by NG-monomethyl-L-arginine (L-NMMA), while 7-nitroindazole (7-NI) was a weak inhibitor and L-cannavine had no effect. 5. Citrulline formation could be inhibited by superoxide dismutase in an oxyhaemoglobin-sensitive manner, suggesting feedback inhibition of NOS by NO. 6. EFS induced prominent NO-mediated relaxations in the urethra while minor or no responses were observed in the detrusor and the ureter, respectively. Urethral relaxations to EFS were inhibited by NOS inhibitors with the rank order of potency: L-NOARG = L-NAME > 7-NI > L-NMMA. 7. In conclusion, we have demonstrated the presence of NO-synthesizing enzymatic activity in the sheep urinary tract which shows similar characteristics to the constitutive NOS isoform found in brain. We suggest that the enzymatic activity measured in the urethral muscle layer may account for the NO-mediated urethral relaxation during micturition whereas regulation of detrusor and ureteral motor function by NOS containing nerves is less likely.

Distribution of nitric oxide synthase-containing ganglionic neuronal somata and postganglionic fibers in the rat kidney

Nitric oxide synthase (NOS)-immunoreactive neurons were identified in the rat kidney by using an antibody against type Ia NOS and the avidin-biotin complex immunoperoxidase method in whole kidneys examined in 100 microns serial sections. The histochemical method for demonstration of the nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) was also used to characterize NOS-containing neurons. All somata showing NOS immunoreactivity also displayed NADPH-d activity. The greatest number of neuronal somata were observed in groups at the wall of the renal pelvis and in the angular space formed by the pole of the renal parenchyma and renal pelvic wall. They were also seen at the renal hilus close to the renal artery and along the interlobar vasculature. The size of the neuronal somata in the 35-day-old rat ranged from 13.6 to 34.8 microns, with a mean size of 21.52 +/- 4.81 microns. Seventy percent, however, ranged in size from 17.8 to 26.8 microns. The shape of the neuronal somata also varied, with the majority having an ovoid or round shape. The distribution of the postganglionic fibers was investigated by means of the camera lucida. Postganglionic fibers projected into the wall of the renal pelvis and/or to the interlobar arteries extending to the arcuate arteries and to the beginning of the afferent arterioles. The NOS-immunoreactive neurons may have a vasodilator and relaxing function on the renal pelvic wall and vasculature. In addition, the presence of NOS-containing nerve fibers in nerve bundles, which are known to have predominantly vasomotor and sensory fibers, suggest that they may have a possible modulatory role on renal neural function.

Distribution of nitric oxide synthase-immunoreactive nerves and identification of the cellular targets of nitric oxide in guinea-pig and human urinary bladder by cGMP immunohistochemistry

The distribution of nerves with the potential to synthesize nitric oxide was examined within the urinary bladder and proximal urethra of humans and guinea-pigs, using an antibody to nitric oxide synthase. Further experiments identified cells in which cGMP-immunoreactivity was induced following exposure to the nitric oxide donor, sodium nitroprusside. These cells represent the potential physiological targets of neuronally released nitric oxide, since activation of soluble guanylate cyclase, and a consequent rise in intracellular cGMP, mediate many of the effects of this transmitter. Nitric oxide synthase-immunoreactivity was widely distributed in the lower urinary tract. In guinea-pigs, 50-68% of all intrinsic vesical neurons expressed nitric oxide synthase-immunoreactivity, while in humans 72-96% of neurons in the wall of the bladder contained nitric oxide synthase. In both humans and guinea-pigs, varicose nitric oxide synthase-immunoreactive nerve terminals provided a moderate innervation to the detrusor muscle of the bladder body, and a denser innervation to the urethral muscle. Immunoreactive nerves also projected to the subepithelium and around blood vessels, but were rarely observed encircling intramural vesical ganglia. Following stimulation with sodium nitroprusside, smooth muscle cells of the urethra expressed strong cGMP-immunoreactivity, but detrusor muscle cells remained uniformly negative. Although the detrusor muscle fibres did not express cGMP, numerous interstitial cells throughout the bladder body demonstrated an intense induction of cGMP-immunoreactivity by sodium nitroprusside. These cells had long dendritic processes extending parallel to the smooth muscle fibres, and contained vimentin, an intermediate filament expressed by cells of mesenchymal origin. Other cell types in which sodium nitroprusside exposure induced cGMP-immunoreactivity were the uroepithelial cells, vascular smooth muscle cells and pericytes, and a small number of varicose nerve terminals. In the guinea-pig, a minor proportion (less than 10%) of intrinsic neurons in the wall of the bladder also expressed cGMP. No intrinsic neurons were observed in specimens of human bladder processed for cGMP immunohistochemistry. The results provide anatomical evidence that nitric oxide may function as a neurotransmitter in the lower urinary tract. Although nerves with the capacity to produce nitric oxide supply both the detrusor muscle and the urethra, distinct regional differences exist in the effects of nitric oxide on the induction of cGMP. If the nitric oxide-mediated induction of cGMP is a reliable indicator of the physiological responsiveness of a cell to nitric oxide, then smooth muscle cells appear to be the predominant targets of nitric oxide in the urethra, while in the bladder body, interstitial cells may serve this role. These findings support previous studies which have implicated nitric oxide as an inhibitory transmitter involved in the relaxation of the bladder neck. Our experiments further indicate that a number of cell types within the lower urinary tract could potentially mediate the effects of endogenously released nitric oxide.

Neuropeptides and neurotransmitter-synthesizing enzymes in intrinsic neurons of the human urinary bladder

The expression of neuropeptides, and the enzymes nitric oxide synthase and tyrosine hydroxylase were examined in intramural ganglia of human urinary bladder using single label immunocytochemistry. Scattered ganglia composed of between 1-36 neurons (median 4) were observed in all layers of the lateral wall of the bladder. These contained immunoreactivity to vasoactive intestinal peptide, nitric oxide synthase, neuropeptide Y, and galanin. Neurons within the bladder were heterogeneous with regard to their content of these antigens, with the proportion of immunopositive cells ranging from 58-84%. Occasional neurons with immunoreactivity to the catecholamine-synthesizing enzyme, tyrosine hydroxylase, were also observed. No cell somata, however, were immunoreactive for enkephalin, substance P, calcitonin gene-related peptide or somatostatin. Varicose terminals entering the ganglia were seen to form pericellular baskets surrounding some of the principal ganglion cells. The most prominent pericellular varicosities were those containing calcitonin gene-related peptide- or vasoactive intestinal peptide-immunoreactivity, followed by those with immunoreactivity for enkephalin, neuropeptide Y, or galanin. Less common were pericellular varicosities with substance P-immunoreactivity, which may represent collateral processes of unmyelinated primary sensory fibres, and presumptive noradrenergic processes containing tyrosine hydroxylase. Some calcitonin gene-related peptide-immunoreactive varicosities constituted a distinct type, terminating as large pericellular boutons 2-4 microns in diameter. Fibres containing nitric oxide synthase- or somatostatin-immunoreactivity were not associated with the intramural neurons. The results demonstrate that intrinsic neurons within the human urinary bladder express a number of neuroactive chemicals, and could in principle form circuits with the potential to support integrative activity.