Expression and distribution of phosphodiesterase isoenzymes in the human male urethra.

OBJECTIVE: To investigate the expression and distribution of phosphodiesterase (PDE) isoenzymes PDE1A, PDE2A, PDE4A, PDE4B, and PDE5A in human urethral tissue. METHODS: Specimens of penile urethra were obtained from male subjects who had undergone male-to-female sex reassignment surgery. Using immunohistochemistry (immunofluorescence), the occurrence of PDE1A, PDE2A, PDE4A, PDE4B, and PDE5A, the neuronal nitric oxide synthase, calcitonin gene-related peptide, and vasoactive intestinal polypeptide was examined in urethral sections. Cytosolic supernatants prepared from isolated human urethral tissue were subjected to Western blot analysis using specific anti-PDE antibodies. RESULTS: Immunosignals specific for PDE1A, 4A, 4B, and 5A were observed in the urethral smooth musculature. The smooth muscle bundles were seen innervated by slender nerve fibers, characterized by the expression of the neuronal nitric oxide synthase, calcitonin gene-related peptide, and vasoactive intestinal polypeptide. The expression of the PDE isoenzymes mentioned was confirmed by Western blotting. CONCLUSION: The results provide evidence for a significance of both the cyclic adenosine monophosphate and cyclic guanosine monophosphate signaling in the control of human urethral smooth muscle. The selective inhibition of PDE isoenzymes might represent a pharmacologic option to influence the function of smooth musculature in the human outflow region.

Phosphodiesterase isoenzymes in the human urethra: a molecular biology and functional study.

Experimental and clinical studies have suggested a role for phosphodiesterase (PDE) isoenzymes in the control of the human lower urinary tract. This study aimed to investigate the expression of PDE isoenzymes and the effects of PDE inhibitors (PDE-Is) in isolated human urethral smooth muscle (USM). The expression of messenger ribonucleic acid (mRNA) specifically encoding for PDE isoenzymes and isoforms (1A, 1B, 1C, 2A, 4A, 4B, 4C, 4D, 5A and 11A) was analyzed by means of reverse transcriptase polymerase chain reaction (RT-PCR). Using a tissue bath technique, the effects of vinpocetine (PDE1-I), erythro-9-(2-hydroxy-3-nonyl)adenine hydrochloride (EHNA-HCl=MEP1) (PDE2-I), rolipram (PDE4-I), sildenafil, vardenafil and tadalafil (PDE5-Is) (0.01-10µM) on the tension of USM induced by norepinephrine were investigated. The production of cyclic guanosine monophosphate (cyclic GMP) and cyclic adenosine monophosphate (cyclic AMP) was measured by means of radioimmunoassays. RT-PCR analysis revealed the expression of PDE1B, PDE1C, PDE4A, PDE4C, PDE4D, PDE5A and PDE11A. The tension induced by norepinephrine (NE) was reversed by the PDE inhibitors with the following rank order of efficacy: rolipram (mean: -39%)≥sildenafil (-35%)>vardenafil (-26%)>tadalafil (-20%)>vinpocetine (-16%)>MEP1 (-2%). The relaxing effects of the drugs were paralleled by an elevation in tissue levels of cyclic AMP and cyclic GMP. Selective inhibitors of PDE4 and PDE5 can antagonize the tension induced by alpha-adrenergic stimulation of USM. PDE inhibition might represent an interesting option to facilitate the relaxation of the human outflow region.

Effects of endopeptidase inhibition on the contraction-relaxation response of isolated human vaginal tissue.

INTRODUCTION.: Vasoactive peptides, such as bradykinin, C-type natriuretic peptide (CNP), vasoactive intestinal polypeptide (VIP), and endothelin 1 (ET-1), are assumed to be involved in the control of female genital vascular and nonvascular smooth muscle. Tissue levels of said peptides are controlled by the activity of endopeptidase enzymes. Theoretically, in female genital tissues, inhibiting the degradation of bradykinin, CNP, and VIP, or the conversion of Big ET-1 into ET-1 should result in an enhancement in smooth muscle relaxation and, thus, an improvement in sexual response. AIM.: Elucidate the effects of the endopeptidase inhibitor KC 12615 on the contraction/relaxation response of isolated human vaginal smooth muscle to Big ET-1, bradykinin, CNP, or VIP. METHODS.: Tissue bath experiments were carried out to ascertain the responses of human vaginal tissue challenged by ET-1 (0.1 µM) to increasing concentrations of bradykinin, CNP, and VIP (0.01 µM, 0.1 µM, and 1 µM, respectively). The effects were also evaluated following preexposure to KC 12615 (10 µM, for 20 minutes). MAIN OUTCOME MEASURES.: Measure the effects of KC 12615 on the relaxation of isolated human vaginal smooth muscle brought about by bradykinin, CNP, or VIP and the contraction mediated by Big ET-1. RESULTS.: The tension induced by ET-1 was reversed by bradykinin, CNP, or VIP (-25 ± 6.6%, -13.3 ± 2.2%, and -17.6 ± 10%, respectively). Big ET-1 induced contraction of the vaginal tissue. Preexposure of the tissue to KC 12615 increased the relaxation exerted by bradykinin, CNP, or VIP (to -39.2 ± 5.8%, -40.7 ± 7.3%, and -44.6 ± 19%, respectively). The contraction induced by Big ET-1 was attenuated in the presence of KC 12615 (to approximately 25% of the initial response). CONCLUSION.: Inhibition of endopeptidase activity can antagonize the contraction of human vaginal tissue induced by Big ET-1 and increase the relaxation induced by vasoactive endogenous peptides.

Arginase enzymes in the human prostate: expression of arginase isoenzymes and effects of arginase inhibitors on isolated human prostate tissue.

UNLABELLED: 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.

Expression and distribution of phosphodiesterase isoenzymes in the human seminal vesicles.

INTRODUCTION: Phosphodiesterase (PDE) isoenzymes have been shown to play a role in the control of human male genital tissues. There are hints from basic research and clinical studies that PDE5 inhibitors may have the ability to retard the male ejaculatory response. While the expression of PDE isoenzymes in the human seminal vesicles (SVs) has been described, the distribution of cyclic adenosine monophosphate (AMP)- and cyclic guanosine monophosphate (GMP)-PDEs has not yet been investigated. AIM: The aim of this study was to elucidate the expression and distribution of PDE isoenzymes PDE3A, PDE4 (isoforms A and B), PDE5A, and PDE11A in human SV tissue. METHODS: Using immunohistochemistry (double-labeling techniques, laser fluorescence microscopy), the occurrence of PDE3A, PDE4A, PDE4B, PDE5A, and PDE11A, the vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP), and protein gene product 9.5 (PGP 9.5) was examined in sections of SV. Cytosolic supernatants prepared from isolated human SV tissue were subjected to Western blot analysis using specific anti-PDE antibodies. MAIN OUTCOME MEASURE: The expression and distribution by of PDE3A, PDE4A, PDE4B, PDE5A, and PDE11A in the human SV were investigated by means of immunohistochemistry and Western blot analysis. RESULTS: Immunosignals specific for PDE3A were seen in both the smooth muscle and the glandular epithelium, whereas staining for PDE4A, PDE5A, and PDE11A was mainly limited to epithelial cells. Varicose nerve fibers transversing the sections also presented staining for PDE3A. In nerve fibers and nerve endings, PDE4A and PDE4B were found co-localized with VIP; PDE5A-positive nerves also presented immunosignals specific for CGRP. The expression of said PDE isoenzymes was confirmed by Western blotting. CONCLUSIONS: The results indicate that cyclic AMP- and cyclic GMP-PDE isoenzymes are involved in the control of secretory activity and efferent neurotransmission in the SV. These findings might be of importance with regard to the identification of new therapeutic avenues to treat premature ejaculation.

Exposure of human seminal vesicle tissue to phosphodiesterase (PDE) inhibitors antagonizes the contraction induced by norepinephrine and increases production of cyclic nucleotides.

OBJECTIVES: To investigate further the role of phosphodiesterase (PDE) isoenzymes in the control of human seminal vesicle (SV) smooth muscle contractility, we examined the functional responses of isolated SV tissue to various PDE inhibitors. It has been suggested that the application of inhibitors of the PDE type 5 may facilitate SV smooth muscle relaxation and, subsequently, retard ejaculatory response. METHODS: Using the organ bath technique, strip preparations of human SV were exposed for 5 minutes to 1 µM of the PDE inhibitors milrinone (PDE3 inhibitor), rolipram, Ro 20-1724 (PDE4 inhibitors), and sildenafil (PDE5 inhibitor). Norepinephrine (NE, alpha agonist) was then added (0,1 µM, 1 µM, and 10 µM) and isometric responses were recorded. A contraction-response curve to NE in the absence of PDE inhibitors was also generated. Drug effects on the production of cyclic adenosine monophosphate (AMP) and cyclic guanosine monophosphate (GMP) were measured by means of radioimmunometric assays. RESULTS: The contraction induced by NE was effectively antagonized by 1 µM of rolipram (83.3% inhibition), Ro 20-1724 (72.3% inhibition), sildenafil (41.6% inhibition), and milrinone (37.5% inhibition). The inhibition of force generation was paralleled by a 1.6-fold to 2.8-fold increase in tissue cyclic AMP (induced by milrinone, rolipram, Ro 20-1724), and a 12-fold rise in cyclic GMP (induced by sildenafil). CONCLUSION: The findings demonstrate that PDE inhibitors can counteract the contraction of human SV mediated by alpha-adrenergic receptors and enhance levels of cyclic nucleotides. This might be of importance with regard to the identification of new options for the pharmacological treatment of premature ejaculation.

Characterization of the effects of various drugs likely to affect smooth muscle tension on isolated human seminal vesicle tissue.

OBJECTIVES: To investigate the effects of different classes of drugs on the isometric tension of isolated human seminal vesicle (SV) tissue. The contractility of human SV contributes to the process of seminal emission during ejaculation. Different endogenous compounds, such as serotonin (5-HT), adenosine triphosphate (ATP), and nitric oxide, have been suggested to be involved in the control of contraction and relaxation of human SV smooth muscle. However, only limited data are available regarding the effects of compounds known to affect smooth musculature on SV contractile activity. METHODS: Using the organ bath technique, the effects of increasing concentrations (10 nm-1 microm/10 microm) of norepinephrine (NE), phenylephrine, endothelin 1, ATP, and 5-HT on human SV tissue at basal tension were studied. In another set-up, SV strip preparations were preincubated with prazosin (alpha-adrenergic blocker), nifedipine and verapamil (Ca(2+)-channel blockers), 2-aminoethoxydiphenyl borate [inositol 1,4,5-trisphosphate (IP(3)) antagonist], cromakalim (K(+)-channel opener), or Y-27632 (ROK inhibitor) (1 microm each, for 10 minutes), followed by the application of NE (0.1 microM, 1 microM, and 10 microm). RESULTS: SV smooth muscle was most effectively contracted by NE (mean = 75% of calibrated scale), phenylephrine (mean = 82% of calibrated scale), and endothelin 1 (mean = 70% calibrated scale), whereas only minor responses to ATP (mean = 10.65% calibrated scale) and 5-HT (mean = 6.3% calibrated scale) were observed. The contraction induced by NE was significantly inhibited after pre-exposure of the tissue to prazosin (-92.4%), cromakalim (-83.7%), 2-aminoethoxydiphenyl borate (-43.1%), Y-27632 (-42.8%), and nifedipine (-32.7%). CONCLUSIONS: alpha-adrenoceptor antagonism, activation of potassium channels, and inhibition of Rho-kinase decrease the sympathetic contraction of SV smooth muscle. This might be of significance with regard to the identification of new pharmacologic avenues to affect the male ejaculatory system.

Effects of phosphodiesterase inhibitors on the contractile responses of isolated human seminal vesicle tissue to adrenergic stimulation.

INTRODUCTION: It has been suggested that the capability of the phosphodiesterase 5 (PDE5) inhibitor sildenafil citrate (VIAGRA) to retard the ejaculatory response may include modulation of the contraction of seminal vesicle (SV) smooth muscle. In fact, it has been shown that PDE inhibitors can reverse the tension of isolated human SV tissue and enhance the production of cyclic AMP and cyclic GMP. AIM: The aim of this study was to examine the effects of selective phosphodiesterase (PDE) inhibitors on both the spontaneous and electrically induced phasic contractions of isolated human SV smooth muscle. MAIN OUTCOME MEASURES: To measure the inhibition exerted by PDE inhibitors vinpocetine (PDE1-inhibitor), rolipram (PDE4-inhibitor), sildenafil, and vardenafil (PDE5-inhibitors) on the phasic contractile response of isolated SV tissue. METHODS: Using the organ bath technique, the effects of increasing concentrations of the PDE inhibitors (1 nM-10 microM) were investigated on phasic contractions of SV tissue strips either mediated by means of electrical field stimulation (EFS) or the alpha(1)-adrenoceptor agonist norepinephrine. RESULTS: The contractile activity in response to EFS was dose-dependently reversed by the PDE inhibitors. The rank order of efficacy was: rolipram > sildenafil >or= vardenafil > vinpocetine. Mean maximum inhibition of contraction was determined as -89.6% (rolipram), -61.3% (sildenafil), -62% (vardenafil), and -46% (vinpocetine). No differences were registered with regard to the effects of sildenafil and vardenafil on the inhibition of the contraction amplitudes. The frequency of the spontaneous contractions (amplitudes/5 minutes) was reduced by 50% in the presence of 2 microM rolipram, 5 microM sildenafil or vardenafil, and 8 microM vinpocetine. CONCLUSION: Our results demonstrate that PDE inhibitors can inhibit EFS-induced and spontaneous contractile activity of isolated human SV tissue. These findings might be of importance with regard to the pharmacological treatment of premature ejaculation.

Female sexual dysfunction: what's new?

PURPOSE OF REVIEW: The aim of this article is to summarize the most important and interesting achievements which have recently been made in the field of female sexual dysfunction. RECENT FINDINGS: During the last years, the characterization of the female sexual response has been re-examined, resulting in new approaches to the description of female sexual dysfunction, diagnostic criteria and (pharmacological and nonpharmacological) treatment options. The focus of this review is to summarize in brief the latest achievements in the classification, diagnosis, and therapy of symptoms of sexual arousal and orgasmic disorders in adult females. SUMMARY: Future research efforts may provide new diagnostic and (pharmacological and nonpharmacological) treatment algorithms suitable for use in daily clinical practice to approach the different categories of female sexual dysfunction symptoms.