Penile arteries and erection

Emerging structural and pathological analyses on the erectile organ, corpus cavernous containing sinusoids

Background

The corpus cavernosum (CC) containing sinusoids plays fundamental roles for erection. Analysis of pathological changes in the erectile system is studied by recent experimental systems. Various in vitro models utilizing genital mesenchymal-derived cells and explant culture systems are summarized.

Methods

3D reconstruction of section images of murine CC was created. Ectopic chondrogenesis in aged mouse CC was shown by a gene expression study revealing the prominent expression of Sox9. Various experimental strategies utilizing mesenchyme-derived primary cells and tissue explants are introduced.

Main Findings

Possible roles of Sox9 in chondrogenesis and its regulation by several signals are suggested. The unique character of genital mesenchyme is shown by various analyses of external genitalia (ExG) derived cells and explant cultures. Such strategies are also applied to the analysis of erectile contraction/relaxation responses to many signals and aging process.

Conclusion

Erectile dysfunction (ED) is one of the essential topics for the modern aged society. More comprehensive studies are necessary to reveal the nature of the erectile system by combining multiple cell culture strategies.

Myography of isolated blood vessels: Considerations for experimental design and combination with supplementary techniques

The study of the mechanisms of regulation of vascular tone is an urgent task of modern science, since diseases of the cardiovascular system remain the main cause of reduction in the quality of life and mortality of the population. Myography (isometric and isobaric) of isolated blood vessels is one of the most physiologically relevant approaches to study the function of cells in the vessel wall. On the one hand, cell-cell interactions as well as mechanical stretch of the vessel wall remain preserved in myography studies, in contrast to studies on isolated cells, e.g., cell culture. On the other hand, in vitro studies in isolated vessels allow control of numerous parameters that are difficult to control in vivo. The aim of this review was to 1) discuss the specifics of experimental design and interpretation of data obtained by myography and 2) highlight the importance of the combined use of myography with various complementary techniques necessary for a deep understanding of vascular physiology.

Sexual Function, Behavior, and Satisfaction in Masters Athletes

Objectives

Masters athletes are endowed with high functional capacity, long-term health, and psychological outlook. However, their sexual activity and function are largely unknown. We investigated the influence of sustained moderate to vigorous exercise on sexual life using a model of masters athletes.

Methods

A 55-item survey adapted from previous American Association of Retired People (AARP) sexuality study were distributed to masters athletes associations. The responses from 166 masters athletes were compared with AARP dataset that represented a general population.

Results

Both male and female masters athletes demonstrated more frequent sexual desire and greater involvements in different types of sexual activities (i.e., kissing or hugging, touching or caressing, sexual intercourse, oral sex, and self-stimulation; all p < 0.05). Sexual satisfaction was greater in female masters athletes than in female general population (p = 0.025), but no such group difference was observed in men. Male athletes had a lower degree of erectile dysfunction. No difference was observed in orgasm frequency between the two population groups. Age-associated decline in sexual activity was apparent in general population (p < 0.05) but absent in masters athletes. Females recorded lower engagements in partner-involved sexual behaviors than men in the general population, but no such gender difference was observed in women. The primary factor predicting improvement in sexual satisfaction was "better health for myself" (29.7%) in the general population, whereas master athletes identified "better health for partner" (23.5%).

Conclusion

Masters athletes in general and female athletes in particular demonstrate superior sexual function, satisfaction, and behavior presumably due to their better overall health status.

MYPT1 reduction is a pathogenic factor of erectile dysfunction

Erectile dysfunction (ED) is closely associated with smooth muscle dysfunction, but its underlying mechanisms remains incompletely understood. We here reported that the reduced expression of myosin phosphatase target subunit 1 (MYPT1), the main regulatory unit of myosin light chain phosphatase, was critical for the development of vasculogenic ED. Male MYPT1 knockout mice had reduced fertility and the penises displayed impaired erections as evidenced by reduced intracavernous pressure (ICP). The penile smooth muscles of the knockout mice displayed enhanced response to G-Protein Couple Receptor agonism and depolarization contractility and resistant relaxation. We further identified a natural compound lotusine that increased the MYPT1 expression by inhibiting SIAH1/2 E3 ligases-mediated protein degradation. This compound sufficiently restored the ICP and improved histological characters of the penile artery of Mypt1 haploinsufficiency mice. In diabetic ED mice (db/db), the decreased expression of MYPT1 was measured, and ICP was improved by lotusine treatment. We conclude that the reduction of MYPT1 is the major pathogenic factor of vasculogenic ED. The restoration of MYPT1 by lotusine improved the function of injured penile smooth muscles, and could be a novel strategy for ED therapy.

Priapism caused by partial deficiency of tetrahydrobiopterin through hypofunction of the sympathetic neurons in sepiapterin reductase gene-disrupted mice

6R-L-erythro-5,6,7,8-tetrahydrobiopterin (BH4) is an essential cofactor for aromatic L-amino acid hydroxylases, including tyrosine hydroxylase (TH), alkylglycerol monooxygenase, and three types of nitric oxide (NO) synthases (NOS). Sepiapterin reductase (SPR) catalyzes the third step of BH4 biosynthesis. SPR gene-disrupted (Spr-/- ) mice exhibit a dystonic posture, low body weight, hyperphenylalaninemia, and unstable hypertension with endothelial dysfunction. In this study, we found that Spr-/- mice suffered from a high incidence of severe priapism. Their erections persisted for months. The biopterin, BH4, and norepinephrine contents, and TH protein levels in the penile tissue of Spr-/- mice without and with priapism were significantly reduced compared to those of Spr+/+ mice. In contrast, their neural NOS (nNOS) protein levels were increased, and the cyclic guanosine monophosphate (cGMP) levels were remarkably elevated in the penises of Spr-/- mice with priapism. The symptoms were relieved by repeated administration of BH4. The biopterin, BH4, and norepinephrine contents were increased in penile homogenates from BH4-supplemented Spr-/- mice, and the TH protein levels tended to increase, and their nitrite plus nitrate levels were significantly lower than those of vehicle-treated Spr-/- mice and were approximately the same as vehicle- and BH4-supplemented Spr+/+ mice. Thus, we deduced that the priapism of Spr-/- mice is primarily caused by hypofunction of the sympathetic neurons due to cofactor depletion and the loss of TH protein and, further, dysregulation of the NO/cGMP signaling pathway, which would be caused by disinhibition of nNOS-containing neurons and/or abnormal catabolism of cyclic nucleotides is suggested.

Use of Infrared Thermography during Ejaculation Process and Its Link with Semen Quality and Freezability in Dogs

Simple Summary

Scientific attention to infrared technology has grown over the last decade. Remote and non-invasive monitoring techniques are of great importance in discovering ejaculation response and future trends because of their role in vascular flux regulation. However, detailed information about its use in andrology has yet to be fully explained. Therefore, we aimed to reveal information about the amount of sperm to be obtained by observing stress levels with non-invasive eye temperature measurement, and the relationship between various reproductive temperature patterns and parameters of the animal’s various physiological conditions such as age, body condition, total ejaculation time and testicular volume.

Abstract

This study aimed to describe the thermal variation of external reproductive tracts during ejaculation in relation to sperm quality in dogs. Forty-six adult fertile dogs were monitored using a thermal camera before, during and after the semen collection, taking into account penile and scrotal temperatures as reproductive thermal patterns while eye and perianal temperatures were recorded as complementary thermal patterns of behavioral response. The parameters were classified depending on age (≤4 years and >4 years), body weight (BW) (≤75 kg and >75 kg), sperm concentration (CON) (≤300 million and >300 million), total testicular volume (TTV) (≤600 cm³ and >600 cm³) and total ejaculation time (TET) (≤800 s and >800 s) of the animals from which semen was collected successfully. Heavier males (p < 0.05) that have more consistent testicles (p < 0.01) as well as quicker ejaculate responders (p < 0.001) and lower scrotal temperature had better semen (Δ motility) freezability. The lower eye temperature prior to the ejaculation (p < 0.01), lower scrotal temperature following ejaculation (p < 0.01), and conversely, higher penile temperature during the ejaculation (p < 0.001) had a higher sperm concentration. Furthermore, the sperm freezability was negatively correlated with total ejaculation time (r = −0.39, p < 0.05) and sperm abnormalities were lower in the ejaculate of dogs having a higher temperature of the scrotum, bulbus and penis. In conclusion, infrared monitoring throughout semen collection in dogs can provide information on behavioral reactions during human manipulation, as well as semen quality and testicular functionality.

Effects of chronic type 5 phosphodiesterase inhibition on penile microvascular reactivity in hypertensive patients with erectile dysfunction: a randomized crossover placebo-controlled trial

This randomized crossover and placebo-controlled trial evaluated the effects of daily use of sildenafil citrate (SIL, 1-month 50 mg twice daily) on penile and systemic endothelial microvascular function in hypertensive patients presenting with erectile dysfunction. The effects of SIL on arterial pressure were evaluated using ambulatory blood pressure monitoring (ABPM). Fifty patients diagnosed with primary arterial hypertension and erectile dysfunction (aged 57.4 ± 5.6 years), recruited in a tertiary public hospital, were treated with SIL (50 mg twice daily) or placebo (PLA) for two 30-day periods with a 30-day washout between them. Laser speckle contrast imaging coupled with acetylcholine skin iontophoresis was used to evaluate penile and systemic (forearm) cutaneous microvascular reactivity. SIL treatment increased penile basal microvascular flow (P = 0.002) and maximal endothelial-dependent peak response to skin iontophoresis of acetylcholine (ACh, P = 0.006). The area under the curve of microvascular vasodilation induced by ACh was also significantly increased (P = 0.02). Lastly, SIL treatment did not modify systemic microvascular reactivity. Twenty-four-hour ABPM (P = 0.0002) and daytime (P = 0.002) and nighttime (P = 0.001) mean diastolic blood pressure values were significantly reduced after SIL treatment. The scores of the Simplified International Index of Erectile Function (P < 0.0001) and the number of patients with positive responses to Sexual Encounter Profile question 3 (P < 0.0001) also increased after SIL treatment. Penile endothelium-dependent microvascular reactivity improved after continuous use of sildenafil in hypertensive patients with erectile dysfunction; the treatment also reduced blood pressure, suggesting that, in addition to improving erectile function, daily use of sildenafil could improve blood pressure control.

Effect of high-density lipoprotein on penile erection: A cross-sectional study

Previous studies have shown that elevated levels of high-density lipoprotein (HDL) could inhibit penile erection, but the relationship between HDL and the erection of the penile tip or base has not been extensively researched. We investigated the effects of HDL on erection of the penile tip and base through a cross-sectional study of 113 patients with erectile dysfunction, using a cut-off score of ≤21 on the International Index of Erectile Function-5. The following patient data were collected: nocturnal penile tumescence; blood pressure; platelet count; platelet distribution width; mean platelet volume; plateletcrit; and levels of serum glucose, total cholesterol, triglyceride, HDL, and low-density lipoprotein. Univariate and multivariate analyses were used to assess the association between HDL levels and the erection of the penile tip and base. We confirmed that HDL had a beneficial effect on penile erectile function. We also found that when the HDL level exceeded the normal range, the change in HDL had a significant effect on the penile base. In addition, our study did not find any relationship between platelet parameters and erection of the penile tip or penile base.

Impact of estrogens in males and androgens in females

Androgens and estrogens are known to be critical regulators of mammalian physiology and development. While these two classes of steroids share similar structures (in general, estrogens are derived from androgens via the enzyme aromatase), they subserve markedly different functions via their specific receptors. In the past, estrogens such as estradiol were thought to be most important in the regulation of female biology, while androgens such as testosterone and dihydrotestosterone were believed to primarily modulate development and physiology in males. However, the emergence of patients with deficiencies in androgen or estrogen hormone synthesis or actions, as well as the development of animal models that specifically target androgen- or estrogen-mediated signaling pathways, have revealed that estrogens and androgens regulate critical biological and pathological processes in both males and females. In fact, the concept of "male" and "female" hormones is an oversimplification of a complex developmental and biological network of steroid actions that directly impacts many organs. In this Review, we will discuss important roles of estrogens in males and androgens in females.

The Relaxant Mechanisms of Hydrogen Sulfide in Corpus Cavernosum

In several animal and human studies, the contribution of the endothelium, nitric oxide/soluble guanosine monophosphate (NO/cGMP) pathway, adenylyl cyclase, phosphodiesterase (PDE), potassium (K⁺) channels, L-type calcium channels, Na⁺-K⁺-ATPase, muscarinic acetylcholine receptors, RhoA/Rho-kinase pathway, and cyclooxygenase (COX)/arachidonic acid cascade on the relaxant mechanism of L-cysteine/H₂S pathway in corpus cavernosum has been investigated. In this chapter the relaxant mechanisms of H₂S in corpus cavernosum is discussed with data available in the current relevant literature. Also, in vitro experimental procedure for mice corpus cavernosum which used to investigate the relaxant effect of H₂S is given in detail.

Cigarette Smoking Is Significantly Linked to Sexual Dissatisfaction in Chinese Heroin-Dependent Patients Receiving Methadone Maintenance Treatment

Background: Cigarette smoking is associated with sexual dysfunction in the general population. Both smoking and sexual dysfunction are common in heroin-dependent patients (HDPs) receiving methadone maintenance treatment (MMT), but their association in MMT HDPs is rarely studied. This study examined the association between smoking and sexual dissatisfaction in Chinese HDPs receiving MMT. Methods: In total, 480 Chinese HDPs, who had sex with their regular or irregular sex partners within one month prior to the study, were included from three MMT clinics in Wuhan, China. Sexual dissatisfaction was assessed with one single question. Socio-demographic and clinical data and smoking characteristics were collected with a standardized questionnaire. Multiple binary logistic regression was used to analyze the association between smoking and sexual dissatisfaction, as well as the associations between levels of smoking and nicotine dependence and sexual dissatisfaction. Results: The prevalence of current smoking was 95.6% in HDPs receiving MMT. Rates of sexual dissatisfaction were higher in current smokers than non-smokers (32.9% vs. 14.3%) with a borderline significant P value of 0.074. After adjusting potential socio-demographic and clinical confounders, current smoking was significantly linked to sexual dissatisfaction (OR = 1.95, P = 0.026), and heavy smoking and severe nicotine dependence were significantly linked to sexual dissatisfaction (OR = 1.80, P = 0.025; OR = 3.27, P < 0.001). Conclusion: Smoking is significantly associated with sexual dysfunction in HDPs receiving MMT. It deserves further investigation as to whether quitting smoking can improve the sexual function of methadone-maintained patients.

Neural substrates of sexual arousal in heterosexual males: event-related fMRI investigation

BACKGROUND

Sexual behavior is an important role for the survival of species. The advancement of brain imaging methods has enabled the understanding of the brain mechanism related to sexual arousal. The previous studies on the brain mechanism related to sexual arousal have mostly conducted on block design paradigm.

METHODS

Despite its requirement for stricter experimental control, the event-related paradigm is known to be more efficient in detecting instant emotional and cognitive responses. The paradigm also enables the observation of hemodynamic responses through time. Therefore, this study used the event-related fMRI to examine the brain activation in various areas associated with sexual arousal as well as changes in hemodynamic responses with time.

RESULTS

Strong activations were observed in the various areas associated with sexual arousal comprised of various factors: (1) activation areas related to cognitive factors: the occipital lobe and parietal lobe; (2) activation areas related to emotional factors: the thalamus and amygdala; (3) activation areas related to motivational factors: the anterior cingulate gyrus, orbitofrontal cortex, and insula; and (4) activation areas related to physiological factors: the precentral gyrus, putamen, and globus pallidus. We also identified the activation of the putamen and globus pallidus that were not well observed in previous block design studies. In the result of the hemodynamic response, the neural activity in those areas showed more transient aspects of the hemodynamic responses relative to the neural activity of other areas.

CONCLUSIONS

These results suggested that the event-related paradigm is better at detecting the neural activity of the brain regions, which tend to appear suddenly, but disappear soon.

Mechanisms Involved in Thromboxane A2 -induced Vasoconstriction of Rat Intracavernous Small Penile Arteries

Diabetes is associated with erectile dysfunction and with hypercontractility in erectile tissue and this is in part ascribed to increased formation of thromboxane. Rho kinase (ROCK) is a key regulator of calcium sensitization and contraction in vascular smooth muscle. This study investigated the role of calcium and ROCK in contraction evoked by activation of the thromboxane receptors. Rat intracavernous penile arteries were mounted for isometric tension and intracellular calcium ([Ca²⁺ ]_i ) recording and corpus cavernosum for measurements of MYPT1 phosphorylation. In penile arteries, U46619 by activation of thromboxane receptors concentration dependently increased calcium and contraction. U46619-induced calcium influx was blocked by nifedipine, a blocker of L-type calcium channels, and by 2-aminoethoxydiphenyl borate, a blocker of transient receptor potential (TRP) channels. Inhibitors of ROCK, Y27632 and glycyl-H1152P, concentration dependently reduced U46619-induced contraction, but only Y27632 reduced [Ca²⁺ ]_i levels in the penile arteries activated with either high extracellular potassium or U46619. MYPT-Thr⁸⁵⁰ phosphorylation in corpus cavernous strips was increased in response to U46619 through activation of TP receptors and was found to be a direct result of phosphorylation by ROCK. Y27632 induced less relaxation in mesenteric arteries, H1152P induced equipotent relaxations, and a protein kinase C inhibitor, Ro-318220, failed to relax intracavernous penile arteries, but induced full relaxation in rat mesenteric arteries. Our findings suggest that U46619 contraction depends on Ca²⁺ influx through L-type and TRP channels, and ROCK-dependent mechanisms in penile arteries. Inhibition of the ROCK pathway is a potential approach for the treatment of erectile dysfunction associated with hypertension and diabetes.

Can the mean platelet volume be a risk factor for vasculogenic erectile dysfunction?

Purpose

The mean platelet volume (MPV) is a marker of the platelet activity and is reported to increase in vascular diseases. We aimed to investigate the association between MPV and vasculogenic erectile dysfunction (ED).

Materials and Methods

MPV and platelet (PLT) levels were measured in 50 cases of ED and 40 healthy controls. The diagnosis of vasculogenic ED was based on a detailed sexual history, physical examination, laboratory assessment, and color Doppler ultrasonography. The results are given as mean±standard deviation of the mean.

Results

The mean ages of the patient and the control groups were 53.70±12.39 years (range 24~77 years) and 53.85±9.5 years (range 30~73 years), respectively (p=0.947). The MPV and PLT values were significantly higher in the patients with ED than those of the controls (7.49±1.4), (6.85±1.2), (262.97±68), (252.89±82) respectively, p<0.001). However, the MPV values were not statistically significantly different in the patients with severe ED according to the International Index of Erectile Function than in those with mild ED, p>0.05), and there was no correlation between MPV and either age of patients (p=0.905) or duration of ED (p=0.583).

Conclusions

The platelet count and MPV was detected to be increased in patients with vasculogenic ED. This finding suggests a role for platelets in the pathogenesis of vascular complications and that the MPV would be useful in monitoring disease progression.

Parasympathomimetic Effect of Shilajit Accounts for Relaxation of Rat Corpus Cavernosum

Previous studies have reported an enhancement of central cholinergic signal cascade by shilajit. For the present study, it was hypothesized that parasympathomimetic effect of shilajit accounting for relaxation of rat corpus cavernosum may be one of the major mechanisms attributing to its traditional role as an aphrodisiac. To test this hypothesis, the acute peripheral effect of standard acetylcholine (ACh), shilajit, and their combination was evaluated on cardiorespiratory parameters such as mean arterial blood pressure (MABP), heart rate (HR), respiratory rate (RR), and neuromuscular transmission (NMT). Furthermore, in vitro effect of standard ACh, shilajit, and their combination was tested on the rat corpus cavernosum. Six groups were used for the in vivo study ( N = 5): Group I (control-saline), Group II (ACh), Group III (Sh), Group IV (Sh followed by ACh), Group V (Atropine followed by ACh), and Group VI (Atropine followed by Sh). The in vitro study included four groups: Group I (control-saline), Group II (ACh), Group III (Sh), and Group IV (Sh followed by ACh). The results of the in vivo study confirmed the peripheral parasympathomimetic effect of shilajit (400 µg/mL). The in vitro results revealed that shilajit (400 and 800 µg/mL) relaxed cavernous strips’ concentration dependently and enhanced ACh-mediated relaxations. The peripheral parasympathomimetic effects of shilajit were confirmed by blockade of shilajit-induced relaxations (in vitro) and shilajit-induced lowering of MABP and HR (in vivo) by atropine.

Mechanisms of penile erection and basis for pharmacological treatment of erectile dysfunction

Erection is basically a spinal reflex that can be initiated by recruitment of penile afferents, both autonomic and somatic, and supraspinal influences from visual, olfactory, and imaginary stimuli. Several central transmitters are involved in the erectile control. Dopamine, acetylcholine, nitric oxide (NO), and peptides, such as oxytocin and adrenocorticotropin/α-melanocyte-stimulating hormone, have a facilitatory role, whereas serotonin may be either facilitatory or inhibitory, and enkephalins are inhibitory. The balance between contractant and relaxant factors controls the degree of contraction of the smooth muscle of the corpora cavernosa (CC) and determines the functional state of the penis. Noradrenaline contracts both CC and penile vessels via stimulation of α₁-adrenoceptors. Neurogenic NO is considered the most important factor for relaxation of penile vessels and CC. The role of other mediators, released from nerves or endothelium, has not been definitely established. Erectile dysfunction (ED), defined as the "inability to achieve or maintain an erection adequate for sexual satisfaction," may have multiple causes and can be classified as psychogenic, vasculogenic or organic, neurologic, and endocrinologic. Many patients with ED respond well to the pharmacological treatments that are currently available, but there are still groups of patients in whom the response is unsatisfactory. The drugs used are able to substitute, partially or completely, the malfunctioning endogenous mechanisms that control penile erection. Most drugs have a direct action on penile tissue facilitating penile smooth muscle relaxation, including oral phosphodiesterase inhibitors and intracavernosal injections of prostaglandin E₁. Irrespective of the underlying cause, these drugs are effective in the majority of cases. Drugs with a central site of action have so far not been very successful. There is a need for therapeutic alternatives. This requires identification of new therapeutic targets and design of new approaches. Research in the field is expanding, and several promising new targets for future drugs have been identified.

Vardenafil demonstrates first-dose success and reliability of penetration and maintenance of erection in men with erectile dysfunction - RELY-II

OBJECTIVE

Vardenafil has been shown to be efficacious in patients with erectile dysfunction (ED). We evaluated first-dose and repeat-dose response to vardenafil 20 mg.

METHODS

This randomized, placebo-controlled study consisted of a 4-week, treatment-free run-in phase; a 1-week, open-label challenge phase; and a 12-week, double-blind treatment phase. Primary efficacy was assessed in terms of reliability of insertion based on dose as measured by the Sexual Encounter Profile question 2 (SEP2). We assessed safety by evaluating adverse events (AEs).

RESULTS

Baseline patient characteristics in the 2 treatment groups were similar. The most common comorbidities were hypertension (41%), dyslipidemia (28%) and diabetes mellitus (24%). Of the 573 patients receiving the 20-mg vardenafil challenge dose, 464 (81%) achieved first-time successful penetration (SEP2), and 401 (70%) reported successful erection maintenance (SEP3). Patients receiving vardenafil 20 mg had statistically (p < 0.001) and clinically superior SEP2 rates (85%) through weeks 0-12, compared with patients receiving placebo (45%). The increase in reliability of insertion was seen within the first 4 weeks of treatment. Vardenafil therapy was statistically (p < 0.001) and clinically superior to placebo for all secondary efficacy end points as well. Most AEs associated with vardenafil were mild to moderate, with headache, flushing and nasal congestion most frequently reported.

CONCLUSION

Vardenafil 20 mg had a high first-dose success rate for both SEP2 (81%) and SEP3 (70%); this was maintained through to the study end point (85% for SEP2 and 78% for SEP3). These findings were achieved in men with frequently associated comorbidities including hypertension, dyslipidemia and diabetes.

Impact of systemically active neurohumoral factors on the erectile response of the rat

INTRODUCTION

Mean arterial pressure (MAP) and specific regulation of penile blood flow are the primary determinants of an erection. While this concept is well recognized, the differential relationship between systemically acting vasoactive factors on arterial pressure and erectile responses is not well described.

AIM

The aim of this study was to determine how the modification of systemic levels of neurohumoral factors impacts on the magnitude and efficiency of the erectile response.

MAIN OUTCOME MEASURES

The main outcome measures for this study are changes in MAP and intracavernosal pressure (ICP) following electrostimulation of the cavernous nerve.

METHODS

Anesthetized adult, male Sprague-Dawley rats were catheterized for measuring MAP (carotid), ICP, and drug administration (vena cava). Erections were induced via cavernous nerve electrostimulation. Vasoactive drug infusions were used to produce changes in MAP levels including: hexamethonium, angiotensin II (ANGII)±hexamethonium, methoxamine±hexamethonium, losartan, MAHMA NONOate, and terbutaline.

RESULTS

In general, ICP and MAP were linearly correlated regardless of treatment. Hexamethonium markedly dropped MAP and proportionately decreased the magnitude of the erectile response. ANGII or methoxamine given to hexamethonium-pretreated or untreated rats increased MAP similarly, but produced contrasting effects on erectile responses. ANGII-induced pressor responses were associated with increased erectile responses whereas all methoxamine treatments markedly decreased erectile responses. Depressor changes with losartan or terbutaline, but not MAHMA NONOate, also impacted negatively on the efficiency of the erectile responses at lower arterial pressures.

CONCLUSIONS

In general, the magnitude of the erectile responses was found to be dependent upon the level of MAP, although the mechanism by which arterial pressure was changed impacted substantially on the characteristics of the relationship. The major finding was that circulation-wide α-adrenoceptor stimulation was extremely deleterious to erectile responses whereas global stimulation of ANG II receptors was actually proerectile. Overall, the results indicate that neurohumoral specificity in systemic hemodynamic control is also critical in establishing the optimal erectile environment in rats.

Role of adenosine signaling in penile erection and erectile disorders

INTRODUCTION

Penile erection is a hemodynamic process, which results from increased flow and retention of blood in the penile organ due to the relaxation of smooth muscle cells. Adenosine, a physiological vasorelaxant, has been shown to be a modulator of penile erection.

AIM

To summarize the research on the role of adenosine signaling in normal penile erection and erectile disorders.

MAIN OUTCOME MEASURES

Evidence in the literature on the association between adenosine signaling and normal and abnormal penile erection, i.e., erectile dysfunction (ED) and priapism.

METHODS

The article reviews the literature on the role of endogenous and exogenous adenosine in normal penile erection, as well as in erectile disorders namely, ED and priapism.

RESULTS

Adenosine has been shown to relax corpus cavernosum from various species including human in both in vivo and in vitro studies. Neuromodulatory role of adenosine in corpus cavernosum has also been demonstrated. Impaired adenosine signaling through A(2B) receptor causes partial resistance of corpus cavernosum, from men with organic ED, to adenosine-mediated relaxation. Increased level of adenosine has been shown to be a causative factor for priapism.

CONCLUSION

Overall, the research reviewed here suggests a general role of exogenous and endogenous adenosine signaling in normal penile erection. From this perspective, it is not surprising that impaired adenosine signaling is associated with ED, and excessive adenosine signaling is associated with priapism. Adenosine signaling represents a potentially important diagnostic and therapeutic target for the treatment of ED and priapism.

Pistachio diet improves erectile function parameters and serum lipid profiles in patients with erectile dysfunction

We investigated the effects of Antep pistachio on International Index of Erectile Function (IIEF) scores, penile color Doppler ultrasound (PCDU) parameters and serum lipid levels in patients with ED. A total of 17 married male patients with ED for at least 12 months were included in this prospective study. Patients were put on a 100 g pistachio nuts diet for 3 weeks. IIEF and PCDU were evaluated before and after the pistachio diet. In addition, plasma total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglyceride were measured before and after dietary modifications from all subjects. Mean IIEF-15 score was 36 ± 7.5 before the diet and 54.2 ± 4.9 after the diet (P=0.001). Similarly, an increase in all five domains of IIEF was observed after the diet (P<0.05). Mean peak systolic velocity values before and after the pistachio diet were 35.5 ± 15.2 and 43.3 ± 12.4 cm s(-1), respectively (P=0.018). After the pistachio diet, TC and LDL levels decreased significantly, whereas HDL level increased (P=0.008, 0.007 and 0.001, respectively). We demonstrated that a pistachio diet improved IIEF scores and PCDU parameters without any associated side effects in patients with ED. Furthermore, the lipid parameters showed statistically significant improvements after this diet.

The mechanism of vacuum constriction devices in penile erection: the NO/cGMP signaling pathway?

The traditional theories believe that vacuum constriction devices (VCD) is the mechanism through a suction chamber promoting penile blood engorgement and maintaining tumescence with a constriction band. For that mechanical nature of the device, many authors and patients consider the devices are passive engorgement, lack of spontaneous erections, and only rely on the constriction bands to prevent venous outflow to maintain the erection. However, recent clinical studies show that many patients using the VCD devices without the constriction band, but still maintain the erections and return to natural erections. The current theories cannot explain this phenomenon. We think that the VCD devices not only through the mechanical nature to prevent venous outflow by the constriction bands to maintain the erection, but also through the suction chamber to stretch and stimulate the corpora cavernosa nerves, muscles, and blood vessels, and led to the neurotransmitter nitric oxide (NO) released. NO as the principal messenger molecule though the NO/cGMP signaling pathway to mediate corporal smooth muscle relaxation and penile erection. The relaxation of corporal smooth muscle creates pressure in the tunica albuginea can prevent venous outflow and maintain erection. This can explains the phenomenon of many patients using the VCD devices without the constriction bands also maintain the erections and return to natural erections. Thus, we put forward the hypothesis that the classical NO/cGMP signaling pathway is also involved in the penile erections when using the VCD devices. In the future, we could design and apply rat-specific VCD devices without the constriction bands in rat model to analyze the cell and molecular changes in rat corpora cavernosa to test this hypothesis.

Reduced expression of SK3 and IK1 channel proteins in the cavernous tissue of diabetic rats

The small (SK3) and intermediate (IK1) conductance calcium-activated potassium channels could have key roles in the endothelium-dependent hyperpolarization factor pathway, which is believed to contribute to normal penile erection function. We aimed to investigate the expression of SK3 and IK1 in diabetic rodents. The experimental diabetes model was induced in 8-week-old male Sprague-Dawley rats (250-300 g) by a single administration of streptozotocin. Both the diabetes mellitus group (DM group, n = 20) and the control group (NDM group, n = 10) were injected with a low dose of apomorphine to allow for the measurement and comparison of the corresponding penile erections. The mRNA and protein expression levels of SK3 and IK1 were measured by reverse transcription polymerase chain reaction and western blot, respectively. Erectile function was significantly decreased in the DM group compared with control group (P < 0.05). The mRNA and protein expression levels of SK3 and IK1 were reduced in the cavernous tissue of diabetic rats compared with the control group (P < 0.05). Diabetes inhibits mRNA and protein expression of both SK3 and IK1 in the cavernous tissue of diabetic rats. This could play a key role in the development of erectile dysfunction in diabetic rats.

NS11021, a novel opener of large-conductance Ca(2+)-activated K(+) channels, enhances erectile responses in rats

BACKGROUND AND PURPOSE

Large-conductance Ca(2+)-activated K(+) channels (BK(Ca)), located on the arterial and corporal smooth muscle, are potential targets for treatment of erectile dysfunction (ED). This study investigated whether NS11021 (1-(3,5-Bis-trifluoromethyl-phenyl)-3-[4-bromo-2-(1H-tetrazol-5-yl)-phenyl]-thiourea), a novel opener of BK(Ca) channels, relaxes erectile tissue in vitro and enhances erectile responses in intact rats. The effects were compared with sildenafil, an inhibitor of phosphodiesterase type 5.

EXPERIMENTAL APPROACH

Patch clamp was used to record whole cell current in rat isolated corpus cavernosum smooth muscle cells (SMCs) and human umbilical vein endothelial cells (HUVECs). Isometric tension was measured in intracavernous arterial rings and corpus cavernosum strips isolated from rats and men, and simultaneous measurements of intracellular Ca(2+) concentration ([Ca(2+)](i)) and tension were performed in intracavernous arteries. Erectile response was measured in anaesthetized rats.

KEY RESULTS

In patch clamp recordings, NS11021 increased currents sensitive to the selective BK(Ca) channel blocker, iberiotoxin (IbTX) in SMCs, but did not modulate K(+) current in HUVECs. NS11021 reduced [Ca(2+)](i) and tension in penile arteries. IbTX inhibited the vasorelaxation induced by NS11021 and sildenafil in human erectile tissue. NS11021 and sildenafil but not vehicle increased erectile responses in anaesthetized rats, an effect which was abolished after pretreatment with tetraethylammonium.

CONCLUSIONS AND IMPLICATIONS

NS11021 leads to relaxation of both intracavernous arteries and corpus cavernosum strips primarily through opening of BK(Ca) channels. It is also effective in facilitating erectile responses in anaesthetized rats. These results suggest a potential for use of BK(Ca) openers in the treatment of ED.

A novel method of seminal vesicle preparation in isolated seminal vesicle experiments in the rat: ring preparation

In this study, we evaluated the efficacy of a novel method of seminal vesicle (SV) preparation-ring preparation method-in isolated SV experiments in the rat. Rat SVs were prepared as strips and rings and applied to organ baths. The relaxation responses by sodium nitroprusside or doxazosin and contractile responses by electrical field stimulation (EFS) were recorded in both groups. We compared the proportion of tissues that showed consistent responses to the stimuli-drug or EFS-in both groups. And magnitudes of the contractile or relaxation responses were also evaluated in the two groups. In strip preparations (n=20), six tissues (30%) showed stable responses to drugs and were regarded to be useful. However, in ring preparations (n=20), 13 tissues (65%) showed stable responses (P<0.001). Similarly, consistent contractile responses to the EFS were recorded in eight strips (40%) and 13 rings (65%) (n=20 in each group; P<0.05). The magnitudes of the relaxations by drugs were not different between the two methods (P=0.42) and the contractions by EFS were higher in ring preparations (P<0.05). The ring preparation seems to be better for responses to drugs and EFS compared with the strip preparations and, therefore, might be an alternative technique for in vitro SV experiments.

Anatomical, immnunohistochemical and physiological characteristics of the vomeronasal vessels in cows and their possible role in vomeronasal reception

The general morphology of the vomeronasal vessels in adult cows was studied following a classic protocol, including optical, confocal and ultrastructural approaches. This anatomical work was completed immunohistochemically. The vomeronasal organ in cows is well developed, and its vessels are considerable in size. This fact allowed some functional properties of the vomeronasal arteries to be evaluated and, for the first time, their isometric tension to be recorded. Our functional studies were in agreement with the immunohistochemistry, and both corroborated the morphological data on the similarity between the vomeronasal vessels and those of the typical erectile tissue. In consequence, the vasoconstriction and vasodilation of the vomeronasal vessels would facilitate an influx and outflow of fluids in the vomeronasal organ, that is to say, this organ in cows would be able to work as a pump mechanism to send chemical signals to the vomeronasal receptor neurones.

Rho kinase is involved in Ca2+ entry of rat penile small arteries

Tonic physiological activity of RhoA/Rho kinase contributes to the maintenance of penile flaccidity through its involvement in the Ca(2+) sensitization of erectile tissue smooth muscle. The present study hypothesized that Rho kinase is also involved in the modulation of Ca(2+) entry induced by alpha(1)-adrenoceptor stimulation of penile arteries. Rat penile arteries were mounted in microvascular myographs for simultaneous measurements of intracellular Ca(2+) ([Ca(2+)](i)) and force. The Rho-kinase inhibitor Y-27632 markedly reduced norepinephrine-mediated electrically induced contractions and the increases in both [Ca(2+)](i) and tension elicited by the alpha(1)-adrenoceptor agonist phenylephrine (Phe). In contrast, the protein kinase C (PKC) inhibitor Ro-31-8220 reduced tension without altering the Phe-induced increase in [Ca(2+)](i). In the presence of nifedipine, Y-27632 still inhibited the non-L-type Ca(2+) signal and blunted Phe contraction. Y-27632 did not impair the capacitative Ca(2+) entry evoked by store depletion with cyclopiazonic acid but largely reduced the Ba(2+) influx stimulated by Phe in fura-2 AM-loaded arteries. The addition of Y-27632 to arteries depolarized with high KCl markedly reduced tension without changing [Ca(2+)](i). In alpha-toxin-permeabilized penile arteries stimulated with threshold Ca(2+) concentrations, Y-27632 inhibited the sensitization induced by either guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) or Phe in the presence of GTPgammaS. However, Y-27632 failed to alter contractions induced by a maximal concentration of free Ca(2+). These results suggest that Rho kinase, besides its contribution to the Ca(2+) sensitization of the contractile proteins, is also involved in the regulation of Ca(2+) entry through a nonselective cation channel activated by alpha(1)-adenoceptor stimulation in rat penile arteries.

Improvement of erectile function with Prelox: a randomized, double-blind, placebo-controlled, crossover trial

In a randomly allocated, double-blind, placebo-controlled, crossover design, 50 patients with mild to moderate erectile dysfunction (ED) were treated for 1 month with placebo or a combination of L-arginine aspartate and Pycnogenol (Prelox). Patients reported sexual function from diaries. Testosterone levels and endothelial NO synthase (e-NOS) were monitored along with routine clinical chemistry. Intake of Pycnogenol for 1 month restored erectile function to normal. Intercourse frequency doubled. e-NOS in spermatozoa and testosterone levels in blood increased significantly. Cholesterol levels and blood pressure were lowered. No unwanted effects were reported. Prelox is a promising alternative to treat mild to moderate ED.

Cutaneous microcirculatory function predicts the responsiveness to tadalafil in patients with erectile dysfunction and coronary artery disease

Despite the proven clinical efficacy of phosphodiesterase inhibitors in the treatment of erectile dysfunction (ED), some patients do not respond to the medication. By means of nailfold capillary microscopy in patients with concomitant coronary artery disease (CAD) and ED, it was evaluated whether the extent of microvascular dysregulation predicts the responsiveness to tadalafil (TAD) in terms of erectile function. The ED of each patient was assessed by the International Index of Erectile Function (IIEF). Patients presenting both, documented CAD and ED, showed a significantly reduced capillary red blood cell velocity (v(RBC)) at rest and after 3 min of ischemia compared with age-matched controls. At 2 h after intake of 20 mg of TAD, a significant increase of v(RBC) at rest as well as during postischemic hyperemia was found. Patients who reported no improvement of their ED after the use of TAD demonstrated no changes in the duration of postischemic (DpH) hyperemia, or even a reduction of the DpH. The majority of the patients, who reported at least one successful sexual intercourse due to TAD, had a prolongation of DpH. We conclude that assessment of microvascular regulation by nailfold capillary microscopy can predict the probability of a treatment failure with phosphodiesterase inhibitors in patients with ED. Moreover, as endothelial dysfunction is the common underlying pathophysiological process of ED and cardiovascular diseases, the test may help to identify patients at risk for the development of atherosclerosis and following cardiovascular events.

Physiological regulation of penile arteries and veins

Recent experimental evidence suggests that arterial insufficiency precedes the structural and functional changes in corpora cavernosa (CC) leading to organic erectile dysfunction (ED). The present review gives an overview of the physiological factors involved in the regulation of penile vasculature. Sympathetic nerves maintain flaccidity and tonically released noradrenaline induces vasoconstriction of both arteries and veins through alpha(1)- and alpha(2)-postsynaptic receptors and downregulates its own release and that of nitric oxide (NO) through alpha(2)-presynaptic receptors. The sympathetic cotransmitter neuropeptide Y (NPY) modulates noradrenergic vasoconstriction in penile small arteries by both enhancing and depressing noradrenaline contractions through Y(1)- and Y(2)-postsynaptic and a NO-independent atypical endothelial receptor, respectively. Activation of alpha(1)-adrenoceptors involves both Ca(2+) influx through L-type and receptor-operated Ca(2+) channels (ROC) and Ca(2+) sensitization mechanisms mediated by protein kinase C (PKC), tyrosine kinases (TKs) and Rho kinase (RhoK). In addition, RhoK can regulate Ca(2+) entry in penile arteries upon receptor stimulation. Vasodilatation of penile arteries and large veins during erection is mediated by neurally released NO. The subsequent increased arterial inflow to the cavernosal sinoids and shear stress on the endothelium lining penile arteries activates endothelial NO production through Akt phosphorylation of endothelial NO synthase (eNOS). NO stimulates guanylate cyclase and increased cyclic guanin 3'-monophosphate (cGMP) levels in turn activate protein kinase G (PKG), which enhances K(+) efflux through Ca(2+)-activated (K(Ca)) and voltage-dependent Ca(2+) (K(v)) channels in penile arteries and veins, respectively. PKG-mediated decrease in Ca(2+) sensitivity and its regulation by RhoK remains to be clarified in penile vasculature. Phosphodiesterase type 5 (PDE5) inhibitors are potent vasodilators of penile resistance arteries and increase the content and effects of basally released endothelial NO. Endothelium-dependent relaxations of penile small arteries also include an endothelium-derived hyperpolarizing factor (EDHF)-type response, which is impaired in diabetes and hypertension-associated ED. Locally produced contractile and relaxant prostanoids regulate penile venous and arterial tone, respectively. The latter activates prostaglandin I (IP) and prostaglandin E (EP) receptors coupled to adenylate cyclase and to the increase of cyclic adenosine monophosphate (cAMP) levels, which in turn stimulates K(+) efflux through ATP-sensitive K(+) (K(ATP)) channels. There is a crosstalk between the cGMP and cAMP signaling pathways in penile small arteries. Relevant issues such as the mechanisms underlying the excitation-secretion coupling of the endothelial cells, as well as those involved in cell proliferation and vascular remodeling of the penile vasculature remain to be elucidated. In addition, only few studies have investigated the changes in structure and function of penile arteries in cardiovascular risk situations leading to ED.

Paraoxonase activity in patients with erectile dysfunction

Paraoxonase (PON1) is a high-density lipoprotein (HDL)-associated enzyme that protects low-density lipoprotein (LDL) and HDL from peroxidation. In this study, PON1 activities were determined in patients with erectile dysfunction (ED) to investigate the relationship between ED and atherosclerosis. Forty patients, who had been diagnosed with ED by the medical and sexual anamnesis and routine laboratory tests, were included in the study. Thirty healthy, sexually active, married and age-matched men were selected as the control group. The patients and controls who underwent surgical or medical treatment in 1-week time and had a systemic disease such as malignancy, liver and renal insufficiency, and active infection and who smoked cigarettes were excluded. PON1 activities were measured spectrophotometrically. Unpaired samples t-test, correlation analyses and multiple linear regression analyses were used for statistical analyses. The results are given as mean+/-standard deviation of mean. The mean ages of the patient and the control groups were 31.05+/-6.90 (range 22-51) and 29.40+/-6.26 (range 19-46), respectively (P=0.307). Serum PON1 levels of the patient and the control groups were found to be 119.05+/-62.11 and 185.04+/-55.64, respectively. The difference between the groups was quite significant (P=0.001). Epidemiological and experimental studies indicate that PON1 activation was lower in individuals who had a tendency to develop atherosclerosis due to comorbidities such as diabetes, familial hypercholesterolemia and kidney disease. In this study, PON1 activity level was found to be significantly lower in ED patients than in control group. The decrease of PON1 activity may have a role in the ethiopathogenesis of ED, and the atherosclerosis development may be faster in the patients due to decreased activity of PON1, which is an antiatherogenic enzyme.

Molecular mechanisms of detrusor and corporal myocyte contraction: identifying targets for pharmacotherapy of bladder and erectile dysfunction

The Post-Genomic age presents many new challenges and opportunities for the improved understanding, diagnosis and treatment of human disease. The long-term goal is to identify molecular correlates of disease processes, and use this information to develop novel and more effective therapeutics. A major hurdle in this regard is ensuring that the molecular targets of interest are indeed relevant to the physiology and/or pathophysiology of the processes being studied, and, moreover, to determine if they are specific to the tissue/organ being investigated. As a first step in this direction, we have reviewed the literature pertaining to bladder and erectile physiology/pharmacology and dysfunction and attempted to summarize some of the critical molecular mechanisms regulating detrusor and corporal myocyte tone. Because of the vast amount of published data, we have limited the scope of this review to consideration of the calcium-mobilizing and calcium-sensitizing pathways in these cells. Despite obvious differences in phenotypic characteristics of the detrusor and corporal myocyte, there are some common molecular changes that may contribute to, for example, the increased myocyte contractility characteristic of bladder and erectile dysfunction (i.e. increased Rho kinase activity and decreased K(+) channel function). Of course, there are also some important distinctions in the pathways that modulate contractility in these two cell types (i.e. the contribution of ryanodine-sensitive calcium stores and the nitric oxide/cGMP pathways). This report highlights some of these similarities and distinctions in the hope that it will encourage scientific discourse and research activity in this area, eventually leading to an improved quality of life for those millions of individuals that are afflicted with bladder and erectile dysfunction.

Real-life safety and efficacy of vardenafil in the treatment of erectile dysfunction-results from 30,010 U.S. patients

INTRODUCTION

Clinical trials show that vardenafil produces effective and satisfactory first-dose success rates and reliability for erection and intercourse in men with erectile dysfunction (ED).

AIM

This study was conducted to evaluate real-life efficacy, safety, and acceptance of vardenafil in men with ED.

METHODS

This open-label, prospective study, conducted in 6,740 U.S. centers, included an initial visit and one or two follow-up visits within a 2-month period of the first vardenafil dose. Vardenafil was administered in 5-20 mg doses.

MAIN OUTCOME MEASURES

Efficacy variables included first-dose success rates for vaginal penetration, maintenance of erection, and satisfaction based on physician and patient assessments. Safety was assessed by adverse events (AEs).

RESULTS

A total of 30,010 men were included in the safety/intent-to-treat (S/ITT) analysis, with 26,043 men in the adjusted S/ITT population. Vardenafil improved erectile function in 78% of men, with 75% rating overall efficacy as "satisfying" or "very satisfying." The overall rates of successful penetration and maintenance with vardenafil following the first dose were 78% and 68%, respectively. For men with mild and moderate ED, first-dose success rates for penetration were 89% and 82%, respectively, and for maintenance, 82% and 71%, respectively. First-dose penetration and maintenance of erection rates were 76% and 66%, respectively, for men with self-reported hypertension, and 70% and 60%, respectively, for men with diabetes mellitus. At study end, 67% of patients preferred to continue using vardenafil. The most frequently reported AEs were headache (4%) and flushing (2%). Vardenafil was well tolerated, with a "satisfied/very satisfied" tolerability rating in 75% of cases as assessed by the physician.

CONCLUSIONS

This observational study demonstrated the tolerability and efficacy of vardenafil in men with ED and comorbidities. Vardenafil provided a high rate of first-dose intercourse success and a favorable safety profile in patients with and without comorbid disease.

Contribution of both Ca2+ entry and Ca2+ sensitization to the alpha1-adrenergic vasoconstriction of rat penile small arteries

Sympathetic adrenergic nerves maintain the flaccid state of the penis through the tonic release of norepinephrine that contracts trabecular and arterial smooth muscle. Simultaneous measurements of intracellular Ca(2+) concentration ([Ca(2+)](i)) and tension and experiments with alpha-toxin-permeabilized arteries were performed in branches of the rat dorsal penile artery to investigate the intracellular Ca(2+) signaling pathways underlying alpha(1)-adrenergic vasoconstriction. Phenylephrine increased both [Ca(2+)](i) and tension, these increases being abolished by extracellular Ca(2+) removal and reduced by about 50% by the L-type Ca(2+) channel blocker nifedipine (0.3 microM). Non-L-type Ca(2+) entry through store-operated channels was studied by inhibiting the sarcoplasmic reticulum Ca(2+)-ATPase with cyclopiazonic acid (CPA). CPA (30 microM) induced variable phasic contractions that were abolished by extracellular Ca(2+) removal and by the store-operated channels antagonist 2-aminoethoxydiphenyl borate (2-APB, 50 microM) and largely inhibited by nifedipine (0.3 microM). CPA induced a sustained increase in [Ca(2+)](i) that was reduced in a Ca(2+)-free medium. Under conditions of L-type channels blockade, Ca(2+) readmission after store depletion with CPA evoked a sustained and marked elevation in [Ca(2+)](i) not coupled to contraction. 2-APB (50 microM) inhibited the rise in [Ca(2+)](i) evoked by CPA and the nifedipine-insensitive increases in both [Ca(2+)](i) and contraction elicited by phenylephrine. In alpha-toxin-permeabilized penile arteries, activation of G proteins with guanosine 5'-O-(3-thiotriphosphate) and of the alpha(1)-adrenoceptor with phenylephrine both enhanced the myofilament sensitivity to Ca(2+). This Ca(2+) sensitization was reduced by selective inhibitors of PKC, tyrosine kinase (TK), and Rho kinase (RhoK) by 43%, 67%, and 82%, respectively. As a whole, the present data suggest the alpha(1)-adrenergic vasoconstriction in penile small arteries involves Ca(2+) entry through both L-type and 2-APB-sensitive receptor-operated channels, as well as Ca(2+) sensitization mechanisms mediated by PKC, TK, and RhoK. A capacitative Ca(2+) entry coupled to noncontractile functions of the smooth muscle cell is also demonstrated.

First-dose success with vardenafil in men with erectile dysfunction and associated comorbidities: RELY-I

First-dose success of phosphodiesterase type 5 (PDE5) inhibitors may be adversely affected in patients with comorbidities. This article reports first-dose success rates for vardenafil 10 mg in men with erectile dysfunction (ED) and associated comorbidities who participated in the challenge phase of the Reliability--Vardenafil for Erectile Dysfunction I study. This study involved an open-label, single-dose, 1-week challenge period where patients who achieved SEP-2 (penetration) success were randomised to vardenafil 10 mg or placebo for 12 weeks in a double-blind manner. The first-dose success rates for SEP-2 and SEP-3 (maintenance of erection to completion of intercourse) were stratified according to comorbidities. Safety was assessed using adverse events (AEs). Of 600 men who received a single 10 mg dose of vardenafil, 32% had hypertension, 16% had diabetes and 19% had dyslipidaemia. Vardenafil demonstrated overall effectiveness, including first-dose SEP-2 and SEP-3 success rates in patients with and without specific comorbidities. Initial overall success rates for SEP-2 and SEP-3 during the challenge phase were 87% and 74% respectively. First-dose SEP-2 and SEP-3 success rates were 84% and 66% in men with hypertension (n = 191); 84% and 72% in men with dyslipidaemia (n = 116); and 75% and 58% in men with diabetes (n = 95). Vardenafil was well tolerated and most AEs, including the most frequently reported flushing (3.5%), were mild to moderate in intensity. Vardenafil 10 mg is generally well tolerated and efficacious, providing first-dose success with a consistently high rate of reliability of penetration and maintenance of erection in men with ED and associated comorbidities.

Effects of tadalafil on myocardial blood flow in patients with coronary artery disease

OBJECTIVE

Erectile dysfunction and coronary artery disease share similar risk factors. Although phosphodiesterase-5 inhibitors used to treat erectile dysfunction do not adversely affect hemodynamic parameters in patients with coronary artery disease, their effects on myocardial blood flow are unknown.

METHODS

In a randomized, double-blind, crossover study we examined the effects of tadalafil, 20 mg, compared with placebo on myocardial blood flow in patients with stable coronary artery disease (n=7, 52-73 years old). After tadalafil or placebo, myocardial blood flow was measured with positron emission tomography (nine-segment model) at rest, during maximal coronary hyperemia with adenosine, and during increased myocardial work with dobutamine. Abnormal flow was defined as myocardial blood flow <75% of maximum perfusion during adenosine plus placebo (46 normal/17 abnormal segments dentified).

RESULTS

Compared with placebo, tadalafil had no significant effect on global myocardial blood flow at rest, during adenosine infusion, or during dobutamine infusion. Similarly, in normal and abnormal segments, tadalafil versus placebo had no significant effect on resting myocardial blood flow or on adenosine-induced increases in myocardial blood flow. In normal segments, myocardial blood flow with dobutamine plus tadalafil was greater than that with dobutamine plus placebo (1.79+/-0.56 versus 1.56+/-0.37 ml/g per min, P<0.01), and in abnormal segments, there was a trend for tadalafil compared with placebo to increase myocardial blood flow during dobutamine infusion (1.46+/-0.44 versus 1.36+/-0.36 ml/g per min, P=0.7).

CONCLUSIONS

Tadalafil had no significant effect on global myocardial blood flow at rest, during adenosine infusion, or during dobutamine infusion. Compared with placebo, tadalafil significantly augmented myocardial blood flow during increased workload in normal regions, with a trend toward improving myocardial blood flow in poorly perfused regions.