Search

To investigate the role of the peptide arginine-vasopressin (AVP) in controlling the function of penile erectile tissue, we determined the course of AVP through different stages of sexual arousal in both the systemic and cavernous blood of healthy males and patients presenting with ED. Twenty-five healthy males and 45 patients with ED were exposed to erotic stimulation to induce sexual arousal. Blood was withdrawn from the corpus cavernosum and a cubital vein during penile flaccidity, tumescence, rigid erection (attained only by the healthy individuals), and detumescence. AVP (ng/l plasma) was determined by means of a radioimmunoassay. Effects of AVP (0.1 to 100 nM) on isolated human CC were examined using a tissue bath system. AVP elicited contraction of isolated CC. In the healthy subjects, a decline in AVP levels (5.4 to 3 ng/l) was seen in the systemic blood when the flaccid penis became rigid. In the cavernous blood, no alterations were registered. In the group of ED patients, AVP in the systemic circulation did not display a transient decline. The drop in systemic AVP in healthy males during sexual stimulation might be a prerequisite to enable penile erection.

Background and AimsThe transient receptor potential cationic channel ankyrin 1 (TRPA1), a channel protein permeable to most divalent cations, has been suggested to play a role in mechano-afferent/efferent signaling (including the release of neurotransmitters) in the human urinary tract (bladder, prostate, and urethra). To date, only a few studies have addressed the expression of this receptor in male and female reproductive tissues. The present study aimed to evaluate human seminal vesicles (SVs) for the expression and localization of TRPA1. MethodsSV tissue was obtained from 5 males who had undergone pelvic surgery due to malignancies of the prostate or urinary bladder. The expression of messenger ribonucleic acid (mRNA) specifically encoding for the TRPA1 protein was elucidated by means of reverse transcriptase polymerase chain reaction (RT-PCR). Using immunohistochemical methods, the distribution of TRPA1 was examined in relation to the endothelial and neuronal nitric oxide synthases (eNOS, nNOS) and the neuropeptides calcitonin gene-related peptide (CGRP) and vasoactive intestinal polypeptide (VIP). ResultsRT-PCR revealed signals related to the expected molecular size of 656 bp. Immunohistochemistry demonstrated that TRPA1 is located in nerves running through the smooth muscle portion of the SV. Here, the protein is in part co-localized with nNOS and CGRP, whereas no co-localization with VIP was registered. Dot-like signals specific for TRPA1 were observed in the cytoplasm of epithelial cells lining the lumen of glandular spaces. The epithelial layer also presented staining for eNOS. The smooth musculature appeared free of immunosignals for TRPA1. ConclusionThe results convincingly show the expression of TRPA1 in nerve endings as well as in epithelial cells of the SV. Based on its location in epithelial cells, TRPA1 might be involved in the mechanism of the NO/cyclic guanosine monophosphate (GMP)-mediated signaling and also the control of secretory function (mediated by cyclic GMP) in the human SV.

Harrina E Rahardjo,1,2 Stefan Ückert,2 Andreas Bannowsky,3 Markus A Kuczyk,2 George T Kedia2,4 1Department of Urology, Universitas Indonesia School of Medicine, Cipto Mangunkusumo Hospital, Jakarta, Indonesia; 2Hannover Medical School, Division of Surgery, Department of Urology & Urological Oncology, Hannover, Germany; 3Imland Hospital GmbH, Department of Urology, Rendsburg, Germany; 4DIAKOVERE GmbH, Friederikenstift Lutheran Hospital, Department of Urology, Hannover, GermanyCorrespondence: Stefan ÜckertHannover Medical School, Department of Urology & Urological Oncology, Hannover, 30623, GermanyTel +49 511 5 32 34 37Fax +49 511 5 32 34 81Email sue_de_99@yahoo.dePurpose: Although it has been supposed that the NO/cyclic GMP system produces inhibitory signals to reduce the resistance of the bladder outlet and urethra during the micturition phase, little is known on the mechanisms controlling the function of urethral smooth muscle. The aim of the present study was to examine in the male and female urethra the expression of phosphodiesterase (PDE) isoenzymes, known as key proteins of the cyclic GMP/AMP signaling.Methods: Urethral tissue was obtained from 4 female cadavers and 7 male patients (who had undergone gender reassignment surgery). The expression of mRNA encoding for PDE1A, 1B, 1C, 2A, 4B, 4D, 5A, 10A and 11A was investigated by means of real-time polymerase chain reaction. Western blot (WB) analysis was conducted to detect PDE isoenzymes.Results: RT-PCR revealed relevant amounts of mRNA encoding for PDE1A, 2A, 4B, 5A, 10A and 11A in male and female urethral tissue. The expression of PDE1A, 2A, 4B and 10A was 2-fold higher in the female than in the male urethra, whereas the expression of PDE11A mRNA was 7-fold higher in the male tissue. In the WB experiments, immunosignals specific for PDE1A, PDE4A and 4B and PDE11A were of higher degree in the female than the male tissue specimens, while an almost equivocal expression of PDE2A, PDE5A and PDE10A was registered.Conclusion: On the level of mRNA and function proteins, different patterns of expression of PDE isoenzymes were registered in human male and female urethra. Future studies may clarify whether inhibition of PDE isoenzymes is likely to facilitate the relaxation of the outflow region in both sexes.Keywords: urethral smooth muscle, phosphodiesterase isoenzymes, cyclic adenosine monophosphate, nitric oxide/cyclic guanosine monophosphate

Rare benign tumours of the kidney comprise a group of very different histogenetic entities. We report a case of a 53-year-old woman who underwent laparoscopic nephrectomy because of a renal mass. The diagnosis of a rare and benign metanephric adenoma was confirmed by histopathology. With less than 200 documented cases, the metanephric adenoma described here is a rarity in everyday urological practice and cannot be distinguished from a malignant tumour of the kidney by clinical examination and/or imaging without histological assessment.Die seltenen gutartigen Tumoren der Niere umfassen eine Gruppe histogenetisch sehr verschiedener Entitäten. Wir berichten über eine 53-jährige Patientin, bei der aufgrund des Verdachts auf Vorliegen eines Nierenzellkarzinoms eine laparoskopische Nephrektomie durchgeführt wurde. In der histologischen Untersuchung zeigte sich der seltene Befund eines benignen metanephrischen Adenoms. Das hier beschriebene metanephrische Adenom stellt mit weniger als 200 dokumentierten Fällen eine Rarität im urologischen Alltag dar und ist klinisch sowie bildmorphologisch ohne histologische Begutachtung derzeitig nicht von einem malignen Tumor der Niere zu unterschieden.

Up until today, there are still uncertainties regarding the occurrence of isoforms of the nitric oxide synthase (eNOS, nNOS) in the human prostate. While nNOS was exclusively seen in slender nerve fibres branching within the transition zone, eNOS was reported in glandular structures and also in small vessels interspersing the tissue. This study aimed to re-evaluate by means of light and electron microscopy (LM, EM), the distribution of eNOS and nNOS in the transition zone of the human prostate. Tissue specimens were obtained from 16 patients who underwent surgery for pelvic malignancies. Using specific antibodies in conjunction with advanced fixation and staining procedures, the occurrence of eNOS and nNOS was investigated. nNOS was detected in nerve fibres interspersing the tissue and was also seen in glandular structures. EM revealed that in glandular epithelial cells immunoreaction for nNOS was limited to the cytoplasmic compartment. Vascular endothelial cells of small vessels transversing glandular structures significantly stained for eNOS, while epithelial layers of prostatic glandules appeared free of eNOS. The results implicate that, in the prostate, nNOS is a mediator of stromal and glandular tissue function, and counteract the assumption of eNOS activity in glandular epithelial cells as a source of NO synthesis.

We developed and validated gas chromatography-mass spectrometry (GC-MS) methods for the simultaneous measurement of amino acids and their metabolites in 10-µL aliquots of human plasma and urine. De novo synthesized trideutero-methyl esters were used as internal standards. Plasma proteins were precipitated by acidified methanol and removed by centrifugation. Supernatants and native urine were evaporated to dryness. Amino acids were first esterified using 2 M HCl in methanol and then amidated using pentafluoropropionic anhydride for electron-capture negative-ion chemical ionization. Time programmes were used for the gas chromatograph oven and the selected-ion monitoring of specific anions. The GC-MS methods were applied in clinical studies on the HELLP syndrome and pediatric kidney transplantation (KTx) focusing on L-arginine-related pathways. We found lower sarcosine (N-methylglycine) and higher asymmetric dimethylarginine (ADMA) plasma concentrations in HELLP syndrome women (n = 7) compared to healthy pregnant women (n = 5) indicating altered methylation. In plasma of pediatric KTx patients, lower guanidinoacetate and homoarginine concentrations were found in plasma but not in urine samples of patients treated with standard mycophenolate mofetil-based immunosuppression (MMF; n = 22) in comparison to matched patients treated with MMF-free immunosuppression (n = 22). On average, the global arginine bioavailability ratio was by about 40% lower in the MMF group compared to the EVR group (P = 0.004). Mycophenolate, the major pharmacologically active metabolite of MMF, is likely to inhibit the arginine:glycine amidinotransferase (AGAT), and to enhance arginase activity in leukocytes and other types of cell of MMF-treated children.

The expression of nitric oxide synthase (NOS) in male and female urogenital tissues has been investigated by using conventional light microscopical immunoperoxidase staining. We present an improved immunohistochemical method for the specific and simultaneous detection of endothelial and neuronal NOS (eNOS/nNOS) in vaginal tissue. Specific antibodies have been used in combination with the tyramide signal amplification method. We found a subepithelial meshwork of varicose nerve fibers. A subpopulation of fibers presented immunoreactivity specific for nNOS. Epithelial cells also showed cytoplasmatic labeling for nNOS. Arteries presenting signals for eNOS in their endothelial layer were found in close proximity to nNOS-positive nerve fibers.

The transient receptor potential cationic channel ankyrin 1 (TRPA1) is a channel protein assumed to act in various human tissues as mechano- and pain sensor and play a role in neurotransmission. The expression of TRPA has already been investigated in the human prostate and urethra, however, only very few studies have addressed the expression and distribution in the male and female genital tract. The present study aimed to investigate by means of immunohistochemistry (double-labeling technique, laser fluorescence microscopy) in the human clitoris and penile erectile tissue the localization of TRPA1 in relation to nNOS, the vasoactive intestinal polypeptide (VIP) and vesicular acetylcholine transporter (VAChT). In the clitoral tissue, TRPA1 was observed in basal epithelial cells and slender nNOS-positive nerve fibers transversing the subepithelial space. To a certain degree, in the clitoral epithelial cells, TRPA1 was found co-localized with vimentin. In human corpus cavernosum, immunoreactivity for TRPA1 was seen in nerves transversing the cavernous sinusoidal space and running alongside small arteries, these nerves also displayed expression of the vesicular acetylcholine transporter protein (VAChT). Varicose nerves containing nNOS or VIP were not immunoreactive for TRPA1. It seems likely that TRPA1 is involved in nitric oxide-mediated afferent sensory transmission in the clitoris while, in penile erectile tissue, a role for TRPA1 in cholinergic signaling might be assumed.

Aside from phosphodiesterase (PDE) isoenzymes, protein kinases (cAK=cyclic AMP-binding protein kinase, cGK=cyclic GMP-binding protein kinase) have also been identified as important receptors for cyclic nucleotides. A significance of protein kinases in the control of the function of the male and female reproductive tract has been suggested; however, up until today, only a few approaches have addressed these enzymes in female genital tissues. The present study aimed to investigate by means of biochemical and immunohistochemical methods the expression of cAK and cGK. The distribution of cAK(I) and cGK(I) in relation to the vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP) and PDE type 4 (PDE4) was also evaluated. Cytosolic supernatants prepared from specimens of vaginal wall smooth muscle or epithelium were subjected to anion exchange chromatography and the activities of cAK and cGK(I) measured. To evaluate the distribution of cAK(I) and cGK(I) in relation to VIP, CGRP and PDE4, immunohistochemistry was conducted in sections of the human vaginal wall (full-wall specimens). Activities representing cGK(I) and cAK(I) were resolved from the chromatography column. Staining specific for cAK(Iα) was identified in both vascular and non-vascular vaginal smooth musculature, immunoreactivity for cGK(Iβ) was observed in the smooth muscle and endothelium of small arteries interspersing the sections. cAK(Iα)-positive vessels were found innervated by slender varicose nerve fibers presenting the expression of VIP and CGRP. These arteries also expressed PDE4. Localization of cAK and cGK in close relation to key mediators of the cyclic AMP (PDE4, VIP) and cyclic GMP (CGRP) pathways indicate that both signaling systems may synergistically work together in human vaginal tissue.

The nitric oxide (NO) pathway plays a role in maintaining the function of the prostate. An impairment in the activity of the NO system may have an impact in the manifestation of lower urinary tract symptomatology and benign prostatic hyperplasia. Arginase enzymes (Arg) counteract the generation of NO by depleting the intracellular pool of L-arginine, known to be the substrate of the NO synthases. This study investigated the expression of arginase type I and II in the human prostate. Nondiseased prostate tissue was obtained during pelvic surgeries (prostatectomy, cystoprostatectomy). Tissue sections were exposed to antibodies directed against Arg I and II, cGMP, the phosphodiesterase 5 and nNOS. The expression of mRNA transcripts encoding for Arg I and Arg II was investigated using molecular biology. Reverse transcriptase polymerase chain reaction (RT-PCR) revealed the presence of mRNA encoding for Arg I and II, immunofluorescence specific for Arg I was seen in the stromal smooth musculature, and labelling for PDE5 and cyclic GMP was also observed. Nerve fibres containing nNOS were identified running across the smooth musculature. Immunostainings for Arg II did not yield signals. These findings are in support of the notion that, in the prostate, Arg is involved in the modulation of the activity of the NO system.

The benign prostatic syndrome, comprising lower urinary tract symptomatology secondary to benign prostatic hyperplasia/enlargement, represents a major health care issue in westernized countries. The pharmacological management involves alpha-adrenoceptor antagonists, intervention into the hormonal control of prostate growth using inhibitors of the enzyme 5-alpha-reductase, and stimulation of the nitric oxide/cyclic GMP pathway by tadalafil, an inhibitor of the phosphodiesterase type 5. This review summarizes the achievements which have been made in the development of drug candidates assumed to offer opportunities as beneficial treatment options in the management of the benign prostatic syndrome. A review of the literature has revealed that the line of development is focusing on drugs interfering with peripheral neuromuscular/neuronal mechanisms (nitric oxide donor drugs, agonists/antagonists of endogenous peptides, botulinum toxin, NX-1207), the steroidal axis (cetrorelix) or the metabolic turn-over (lonidamine), as well as the combination of drugs already established in the treatment of lower urinary tract symptomatology/benign prostatic hyperplasia (phosphodiesterase 5 inhibitor plus alpha-adrenoceptor antagonist). Many research efforts have provided the basis for the development of new therapeutic modalities for the management of lower urinary tract dysfunctions, some of which might be offered to the patients in the near future.

Studies on erectile dysfunction (ED) have revealed a relationship between smooth muscle atrophy and the accumulation of collagen in the corpus cavernosum (CC). Transforming growth factor s1 (TGF s1) is a cytokine which has been proposed to be involved in the fibrotic process in the CC. We aimed to evaluate the course of TGF s1 in the systemic and cavernous blood of 17 healthy males through different phases of the sexual arousal response (exemplified by the penile conditions flaccidity, tumescence, rigidity and detumescence). An enzyme-linked immunoassay was used to measure the concentration of TGF s1 (ng/ml) in both the systemic and cavernous blood at the stages of flaccidity, tumescence and detumescence. TGF levels were significantly higher in the cavernous compartment than in the systemic blood. A linear decrease was evident in the cavernous blood when the flaccid penis became tumescent (24.3 ± 14.5 to 13.9 ± 6.5) and rigid (to 8.7 ± 3.1). At detumescence, TGF increased to 18.3 ± 10.4. In contrast, the levels in the systemic circulation remained unchanged. The results are in support of the hypothesis that the concentration of TGF s1 in the CC is regulated by adequate blood flow and oxygenation.

Peptides, such as C-type natriuretic peptide (CNP), vasoactive intestinal polypeptide (VIP) and endothelin 1 (ET-1), are involved in the control of penile erectile tissue (corpus cavernosum = CC). Inhibiting the degradation of CNP and VIP or conversion of Big ET-1 into ET-1 by endopeptidase enzymes should result in an enhancement of CC smooth muscle relaxation. Using the tissue bath technique, responses of isolated CC, challenged by noradrenaline (NA, 1 μm), to increasing concentrations of the endopeptidase inhibitor KC 12615 (1 nm - 10 μm), CNP and VIP (0.1 nm - 1 μm), were investigated. Effects of CNP, VIP and Big ET-1 (0.1 nm - 100 nm) on the tissue tension were also evaluated following pre-exposure to 10 μm of KC 12615. Big ET-1 induced contraction of the CC amounting to a force generation of 1,200 mg. The contraction was attenuated in the presence of KC 12615 by 35% and 50%, respectively. The tension induced by NA was reversed by VIP and CNP to 38.7% ± 15.8% and 61% ± 13%, respectively, of the initial force. The findings might be of significance with regard to future pharmacological treatment options for male ED, where an endothelial dysfunction exists.

S-Nitrosothiols or thionitrites with the general formula RSNO are formally composed of the nitrosyl cation (NO+) and a thiolate (RS−), the base of the corresponding acids RSH. The smallest S-nitrosothiol is HSNO and derives from hydrogen sulfide (HSH, H2S). The most common physiological S-nitrosothiols are derived from the amino acid L -cysteine (CysSH). Thus, the simplest S-nitrosothiol is S-nitroso- L -cysteine (CysSNO). CysSNO is a spontaneous potent donor of nitric oxide (NO) which activates soluble guanylyl cyclase to form cyclic guanosine monophosphate (cGMP). This activation is associated with multiple biological actions that include relaxation of smooth muscle cells and inhibition of platelet aggregation. Like NO, CysSNO is a short-lived species and occurs physiologically at concentrations around 1 nM in human blood. CysSNO can be formed from CysSH and higher oxides of NO including nitrous acid (HONO) and its anhydride (N2O3). The most characteristic feature of RSNO is the S-transnitrosation reaction by which the NO+ group is reversibly transferred to another thiolate. By this way numerous RSNO can be formed such as the low-molecular-mass S-nitroso-N-acetyl- L -cysteine (SNAC) and S-nitroso-glutathione (GSNO), and the high-molecular-mass S-nitrosol- L -cysteine hemoglobin (HbCysSNO) present in erythrocytes and S-nitrosol- L -cysteine albumin (AlbCysSNO) present in plasma at concentrations of the order of 200 nM. All above mentioned RSNO exert NO-related biological activity, but they must be administered intravenously. This important drawback can be overcome by lipophilic charge-free RSNO. Thus, we prepared the ethyl ester of SNAC, the S-nitroso-N-acetyl- L -cysteine ethyl ester (SNACET), from synthetic N-acetyl- L -cysteine ethyl ester (NACET). Both NACET and SNACET have improved pharmacological features over N-acetyl- L -cysteine (NAC) and S-nitroso-N-acetyl- L -cysteine (SNAC), respectively, including higher oral bioavailability. SNACET exerts NO-related activities which can be utilized in the urogenital tract and in the cardiovascular system. NACET, with high oral bioavailability, is a strong antioxidant and abundant precursor of GSH, unlike its free acid N-acetyl- L -cysteine (NAC). Here, we review the chemical and pharmacological properties of SNACET and NACET as well as their analytical chemistry. We also report new results from the ingestion of S-[15N]nitroso-N-acetyl- L -cysteine ethyl ester (S15NACET) demonstrating the favorable pharmacological profile of SNACET.

International audience; We recently found that renal carbonic anhydrase (CA) is involved in the reabsorption of inorganic nitrite (NO2−), an abundant reservoir of nitric oxide (NO) in tissues and cells. Impaired NO synthesis in the endothelium and decreased NO bioavailability in the circulation are considered major contributors to the development and progression of renal and cardiovascular diseases in different conditions including diabetes. Isolated human and bovine erythrocytic CAII and CAIV can convert nitrite to nitrous acid (HONO) and its anhydride N2O3 which, in the presence of thiols (RSH), are further converted to S-nitrosothiols (RSNO) and NO. Thus, CA may be responsible both for the homeostasis of nitrite and for its bioactivation to RSNO/NO. We hypothesized that enhanced excretion of nitrite in the urine may contribute to NO-related dysfunctions in the renal and cardiovascular systems, and proposed the urinary nitrate-to-nitrite molar ratio, i.e., UNOxR, as a measure of renal CA-dependent excretion of nitrite. Based on results from clinical and experimental animal studies, here, we report on a first evaluation of UNOxR. We determined UNOxR values in preterm neonates, healthy children, and adults, in children suffering from type 1 diabetes mellitus (T1DM) or Duchenne muscular dystrophy (DMD), in elderly subjects suffering from chronic rheumatic diseases, type 2 diabetes mellitus (T2DM), coronary artery disease (CAD), or peripheral arterial occlusive disease (PAOD). We also determined UNOxR values in healthy young men who ingested isosorbide dinitrate (ISDN), pentaerythrityl tetranitrate (PETN), or inorganic nitrate. In addition, we tested the utility of UNOxR in two animal models, i.e., the LEW.1AR1-iddm rat, an animal model of human T1DM, and the APOE*3-Leiden.CETP mice, a model of human dyslipidemia. Mean UNOxR values were lower in adult patients with rheumatic diseases (187) and in T2DM patients of the DALI study (74) as compared to healthy elderly adults (660) and healthy young men (1500). The intra- and inter-variabilities of UNOxR were of the order of 50% in young and elderly healthy subjects. UNOxR values were lower in black compared to white boys (314 vs. 483, P = 0.007), which is in line with reported lower NO bioavailability in black ethnicity. Mean UNOxR values were lower in DMD (424) compared to healthy (730) children, but they were higher in T1DM children (1192). ISDN (3 × 30 mg) decreased stronger UNOxR compared to PETN (3 × 80 mg) after 1 day (P = 0.046) and after 5 days (P = 0.0016) of oral administration of therapeutically equivalent doses. In healthy young men who ingested NaNO3 (0.1 mmol/kg/d), UNOxR was higher than in those who ingested the same dose of NaCl (1709 vs. 369). In LEW.1AR1-iddm rats, mean UNOxR values were lower than in healthy rats (198 vs. 308) and comparable to those in APOE*3-Leiden.CETP mice (151).

The endocannabinoid system (ECS), comprising the cannabinoid receptors (CBR), their ligands, and enzymes controlling the turnover of endocannabinoids, has been suggested to be involved in male reproductive function. As information is scarce on the expression of the ECS in human male reproductive tissues, this study aimed to investigate by means of molecular biology (RT-PCR) and immunohistochemistry/immunofluorescence the expression and distribution of CB1 and CB2, GPR55 (an orphan G protein-coupled receptor that recognises cannabinoid ligands) and FAAH (isoforms 1 and 2) in the human seminal vesicles (SV). The specimens expressed PCR products corresponding to CB1 (66 bp), CB2 (141 bp), GPR55 (112 bp), FAAH1 (260 bp) and FAAH2 (387 bp). Immumohistochemistry revealed dense expression of CB1, CB2 and GPR55 located to the pseudo-stratified columnar epithelium and varicose nerves (also characterised by the expression of vasoactive intestinal polypeptide and calcitonin gene-related peptide). Cytosolic staining for FAAH1 and FAAH2 was seen in cuboidal cells of all layers of the epithelium. No immunoreactivity was detected in the smooth musculature or nerve fibres. CB1, CB2, GPR55, FAAH1 and FAAH2 are highly expressed in the human SV. Considering their localisation, the ECS may be involved in epithelial homeostasis, secretory function or autonomic mechano-afferent signalling.

Over the last 20 years, basic and clinical research activities studying the male and female sexual responses have led to several pharmacological options to treat male erectile dysfunction (ED) and female arousal and orgasmic disorders. While some strategies exclusively focus on peripheral mechanisms--such as nitric oxide/cyclic GMP signaling, which is known to play a role in the control of genital vascular and nonvascular smooth muscle--others have considered the central pathways involved in mediating arousal and orgasmic functions in females as well as the induction of penile erection in males. Aside from dopaminergic agonists, drugs known to target the central melanocortin system have also been assumed to have a promising potential in the treatment of female and male sexual dysfunctions.The present review summarizes the achievements that have been made in the clinical development of melanocortin receptor (MCR) agonists (melanotan I, melanotan II, bremelanotide) for the treatment of symptoms of sexual arousal and orgasmic disorders in adult females and ED in males.The data available at present have facilitated our understanding of how the melanocortin pathway regulates both the male and female sexual functions. Indeed the data warrant further investigation to demonstrate the impact of the activation of MCRs by specific agonists on penile erection and female arousal and orgasm function.

Peptides, such as CNP, CGRP and VIP, are involved in the function of male penile erectile tissue. Tissue levels of said peptides are controlled by the endopeptidase enzymes. Theoretically, the inhibition of the degradation of CNP, CGRP and/or VIP should result in an enhancement in penile smooth muscle relaxation. The effects were investigated of CNP or VIP (0.1 nm-1 μm), without and following pre-exposure of the tissue to a threshold concentration of the endopeptidase inhibitor KC 12615 (10 μm, for 20 min), on the reversion of tension induced by means of electrical field stimulation. Drug effects on the production of cyclic AMP/GMP were also evaluated. Neither KC 12615, CNP and VIP nor the combination of CNP plus KC 12615 or VIP plus KC 12615 increased the response of the tissue to EFS. While no effects were observed of a pre-exposure of the tissue to KC 12615 on the production of cyclic AMP in the presence of VIP, an enhancement was registered in the accumulation of cyclic AMP in the presence of CNP plus KC 12615. Further studies are indicated to investigate whether endopeptidase inhibitors might tend to be more effective in tissues affected by a decreased local production of vasoactive peptides.

What's known on the subject? and What does the study add? A previous study by Lexander et al. in 2005, using two-dimensional gel electrophoresis, demonstrated the expression of arginase type II in the different anatomical regions of the prostate; however, to date, no study has addressed, using an in vitro approach, the role of arginase isoenzymes in the human prostate. The results of the present study demonstrate that: both arginase isoenzymes, Arg I and Arg II, are expressed in the transition zone of the human prostate; the inhibition of arginase antagonized, to a certain degree, the tension brought about by noradrenaline in isolated human prostate tissue; exposure of human prostate tissue to arginase inhibitors enhanced the local production of cyclic GMP; and inhibition of arginase enzymes in the human prostate may augment the activity of the nitric oxide/cyclicGMP pathway. OBJECTIVE • To investigate the expression of arginase isoenzymes type I (Arg I) and type II (Arg II) in the transition zone of the human prostate and the functional significance of arginase enzymes in the control of prostate smooth muscle. MATERIALS AND METHODS • Human prostate tissue was obtained from male patients who had undergone pelvic surgery. • The expression of Arg I and Arg II was investigated using Western blot analysis. • Using the organ bath technique, the effects of cumulative administration of difluoromethylornithine (DFMO), H-Orn-OH × HCl, H-Ile-OH and N-ω-hydroxy-nor-L-arginine (nor-NOHA; 1 nM–10 µM) on the tension induced by noradrenaline in isolated prostate tissue were assessed. • Tissue strips were also exposed to arginase inhibitors and the production of cyclic GMP was determined. RESULTS • Western blot analysis showed the expression of Arg I and Arg II in the transition zone of the prostate. • The tension induced by noradrenaline was antagonized by the drugs in the following rank order of efficacy: H-Orn-OH × HCl ≥ H-Ile-OH ≥ DFMO > nor-NOHA; however, the maximum reversion of tension recorded ranged from only −25 to −13%. • The enhancement in cyclic GMP production registered in the presence of the arginase inhibitors ranged from four- to 14-fold. CONCLUSIONS • Arg I and Arg II are expressed in the transition zone of the human prostate. • Isometric tension studies and measurement of cyclic GMP showed that inhibition of arginase can reverse, to a certain degree, the tension of human prostate tissue induced by the activation of α-adrenoceptors and enhance the accumulation of cyclic GMP. • Future studies should explore further the role of arginase enzymes in the relaxation mediated by nitric oxide in prostate smooth muscle.

The spasmolytic activity of flavoxate (CAS 15301-69-6) and the anticholinergic agents oxybutynin (CAS 5633-20-5), tolterodine (CAS 124937-51-5) and trospium chloride (CAS 10405-02-4), all of which are commonly utilized in the treatment of urinary incontinence, on muscarinic tension and electrically evoked contractions of isolated human detrusor smooth muscle strips was studied using the organ bath technique. Within the concentration ranges tested (trospium chloride 10(-11)-10(-6) mol/l, flavoxate and oxybutynin 10(-9)-10(-5) mol/l, tolterodine 10(-10)-10(-5) mol/l), each drug caused a concentration-dependent relaxation of the tension elicited by muscarinic stimulation and dose-dependently attenuated the contractions induced by electrical field stimulation (EFS). The effects of trospium chloride and tolterodine on carbachol-induced muscarinic tension were more pronounced than those of oxybutynin, while trospium chloride and oxybutynin were most effective in inhibiting the contractions induced by EFS. Flavoxate was significantly less effective than all other drugs tested. Regardless the individual drug concentrations needed for maximal efficacy, the potency of oxybutynin and flavoxate to reverse muscarinic tension and attenuate EFS-evoked contractions was almost comparable while tolterodine and trospium chloride were more effective in relaxing the muscarinic tension of the detrusor strip preparations than causing inhibition of EFS-induced contractions. Our results again underline the ratio for the use of nortropane analogues (trospium chloride) and phenylpropylamine cresols (tolterodine) in the treatment of frequency, urgency and urge incontinence secondary to an overactive bladder.

Introduction The calcium-sensitizing Rho A/Rho kinase pathway has been suggested to play a role in the control of nongenital vascular smooth muscle. Rho-associated kinases (ROKs) cause calcium-independent modulation of smooth muscle contraction, and have been demonstrated in the bladder, prostate, and corpus cavernosum. Until now, it is not known whether ROKs and related proteins play a role in the control of vaginal blood flow. Aim To investigate by means of functional studies and immunohistochemistry the significance of the Rho pathway in human vaginal arteries. Methods Vaginal tissue was obtained from five postmenopausal women. Specimens were processed for immunohistochemistry for ROK1, ROK2, RhoA, and RhoGDI. Segments of sub-epithelial vaginal arteries were mounted in a tissue bath. Effects of Y27632 on the concentration–response curves to phenylephrine (Phe) or Phe-precontracted preparations were investigated. Main Outcome Measure The expression of Rho kinases ROK1, ROK2, and the Rho-associated protein RhoGDI in human vaginal arteries was investigated by means of immunohistochemistry. Tissue bath studies were conducted in order to characterize the effects of the ROK inhibitor Y27632 on isolated vaginal arteries. Results A meshwork of α-actin immunoreactive arterioles was located in the sub-epithelium of human vaginal specimens. Immunoreactivities for ROK1, ROK2, RhoA, and RhoGDI were expressed in the smooth musculature of these arteries. At 0.1 and 1 µM Y27632, the contraction to Phe (10 µM) was 99 ± 17% and 28 ± 12% that of 124 mM K+. In Phe-contracted preparations, Y27632 produced relaxant responses. Conclusions The activation of alpha1-adrenoceptors contracts sub-epithelial human vaginal arteries via ROK-sensitive mechanisms. A role for these signals in the regulation of vaginal blood flow might be considered.

Although histamine has been suggested to be involved in the control of male sexual function, including the induction of penile erection, its role in the human corpus cavernosum penis is still poorly understood. The aim of our study was to evaluate the course of histamine plasma levels through different stages of sexual arousal in the systemic and cavernous blood of healthy male subjects. Thirty four (34) healthy men were exposed to erotic stimuli to elicit penile erection. Blood was aspirated from the corpus cavernosum and a cubital vein during the penile conditions flaccidity, tumescence, rigidity and detumescence. Blood was also collected in the post-ejaculatory period. Plasma levels of histamine (ng ml(-1)) were determined by means of a radioimmunoassay. Histamine slightly decreased in the cavernous blood when the penis became tumescent. During rigidity, histamine decreased further but remained unaltered in the phase of detumescence and after ejaculation. In the systemic circulation, no alterations were observed with the initiation or termination of penile erection, whereas a significant drop was registered following ejaculation. Results are not in favour of the hypothesis of an excitatory role of histamine in the control of penile erection. Nevertheless, the amine might mediate biological events during the post-ejaculatory period.

Several disorders of the human upper and lower urinary tract, such as urinary stone disease, lower urinary tract symptoms (LUTS) due to benign prostatic hyperplasia (BPH) and detrusor overactivity, can be therapeutically addressed by influencing the function of the smooth musculature of the ureter, prostate or urinary bladder, respectively. In order to ensure a drug effect without significant adverse events, a certain degree of tissue selectivity is mandatory. The treatment of said conditions aims to focus on orally available drugs acting via intracellular signalling pathways. Specifically, the cyclic nucleotide monophosphate cyclic GMP represents an important mediator in the control of the outflow region (bladder, urethra). The use of phosphodiesterase (PDE) inhibitors, such as sildenafil, tadalafil, vardenafil, avanafil or udenafil, known to restrain the degradation of the second messenger cyclic GMP, offers great opportunities in the treatment of lower urinary tract dysfunction. PDE inhibitors are regarded as efficacious, have a rapid onset of action and favourable effect-to-side-effect ratio. The role of PDE5 inhibitors in the treatment of BPH/LUTS and the overactive bladder has already been addressed in randomized, double-blind, placebo-controlled trials, as well as preliminary open-label studies enrolling either several hundreds or only 20 patients. The purpose of this review is to focus on the potential use and clinical significance of PDE inhibitors in the treatment of storage and voiding dysfunctions of the lower urinary tract. The strategy of modulating the activity of PDE isoenzymes might represent a novel approach in patients with lower urinary tract dysfunction (LUTD).

Summary Neuropeptide Y (NPY) has been shown to induce contraction of isolated human penile erectile tissue and potentiate the response to noradrenaline. The purpose of our study was to measure in the cavernous and systemic blood of healthy male volunteers the course of NPY through different stages of sexual arousal. Whole blood was drawn simultaneously from the corpus cavernosum and the cubital vein of 16 healthy male volunteers during penile flaccidity, tumescence, rigidity and detumescence. Tumescence and erection were induced by applying audiovisual and tactile stimulation. Plasma levels of NPY (given in pmol l–1) were determined by means of an enzyme-linked immunoassay. NPY significantly decreased in the cavernous blood on sexual arousal, when the flaccid penis became tumescent and, finally, rigid (F: 88.8 ± 35.8, T: 62.4 ± 22.7, R: 62.3 ± 19.7), and only slightly rose in the phase of detumescence (64.8 ± 23). In the systemic circulation, no pronounced alterations in the concentration of NPY were registered (F: 64.4 ± 27, T: 65.8 ± 19, R: 59.6 ± 25, D: 67.6 ± 29.3). Our findings are in favour of the hypothesis that NPY could contribute to the maintenance of the resting state of cavernous smooth muscle.

The clitoris contributes to the normal female sexual response cycle. A significance of cyclic guanosine monophosphate (GMP) has been assumed in the control of clitoral vascular smooth muscle. As only a few investigations on the physiology of the vascular and non-vascular clitoral tissue have been carried out, knowledge on the mechanisms controlling this particular female genital organ is still vague. It has been suggested that human clitoral corpus cavernosum smooth muscle is regulated by nitric oxide (NO)/cyclic GMP and related key enzymes, such as NO synthases (NOSs) and the phosphodiesterase type 5 (PDE5). The present study evaluated in the human clitoris, by means of immunohistochemistry, the expression and distribution of key enzymes of the cyclic GMP pathway, such as the endothelial NOS, PDE2, PDE11 and cyclic GMP-dependent protein kinase type I (cGKI) in relation to the PDE5. Immunohistochemistry revealed the presence of PDE2, PDE5 and cGKI in the smooth muscle wall of blood vessels transversing the supepithelial and stromal space. Immunosignals specific for PDE2 were also identified in interstitial-like cells located in the basal epithelial layer. Staining for PDE11A was observed in single nerve trunks located in the clitoral stroma. The results are in favor of a role of the cyclic GMP signaling in the control of clitoral blood flow. It seems likely that PDE2 and PDE11 are also involved in the mechanism of local (neuro)transmission in the clitoris.

It has been assumed that β-endorphin, belonging to the family of opiodergic neuropeptides, might facilitate the inhibition of the male sexual response; however, its role in the control of the penile erectile tissue remains to be elucidated. This study aimed to evaluate in healthy men the course of β-endorphin in the systemic and cavernous blood through different stages of sexual arousal. Thirty-four (34) men were exposed to erotic stimuli to induce penile tumescence and rigidity. Blood was aspirated from the corpus cavernosum and a cubital vein during the penile conditions flaccidity, tumescence, rigidity and detumescence. Plasma levels of β-endorphin were determined by means of radioimmunometric methods. The effects of β-endorphin on isolated human penile erectile tissue were investigated in vitro. β-endorphin did not induce a contractile response of the cavernous tissue or reverse the contraction induced by noradrenaline. β-endorphin decreased in the systemic blood when the penis became tumescent and rigid and increased during detumescence. In the cavernous blood, no alterations in β-endorphin concentrations were observed. The drop in β-endorphin observed during tumescence and rigidity seems likely to reflect the inhibition of the opioidergic input with the beginning of sexual arousal.