Cavernosal Smooth Muscle Relaxation Research Articles

6-Nitrodopamine is an endogenous mediator of the rabbit corpus cavernosum relaxation.

6-Nitrodopamine (6-ND) is a novel endogenous catecholamine that has a potent relaxant action on vascular smooth muscle in vitro. To evaluate the basal release of 6-ND and noradrenaline from rabbit-isolated corpus cavernosum (RbCC) and its relaxing action on this tissue. Rabbit corpus cavernosa were dissected and suspended in a 5-mL organ bath containing oxygenated Krebs-Henseleit's solution. 6-ND and noradrenaline release was quantified by liquid chromatography coupled to tandem mass spectrometry. The relaxant activity of 6-ND was assessed in RbCC strips pre-contracted with endothelin-1 (10nM). Rabbit corpus cavernosum presented basal release of both 6-ND (2.9±0.8ng/mL, n=12) and noradrenaline (1.7±1.3ng/mL, n=12). The 6-ND release was reduced by pre-treatment with Nω -nitro-l-arginine methyl ester (l-NAME) (100 µM), whereas that of noradrenaline was unaffected. Tetrodotoxin (TTX, 1 µM) abolished the noradrenaline release but had no effect on 6-ND release, indicating a non-neurogenic origin for 6-ND. 6-ND and the selective dopamine D2 -agonist L-741,626 caused concentration-dependent RbCC relaxations (pEC50 of 11±0.15 and 11.15±0.28, respectively). Pre-treatment with either l-NAME or the soluble guanylate cyclase inhibitor 1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-on (ODQ) (100 µM) caused a rightward shift of the concentration-response curve to 6-ND, without affecting the L-741,626 responses. In TTX (100nM)-pre-treated preparations, neither l-NAME nor ODQ shifted the 6-ND concentration-response curve. Dopamine, noradrenaline, and adrenaline caused concentration-dependent RbCC contractions. Pre-incubation with 6-ND concentration-dependently inhibited the dopamine-induced contractions, without affecting those induced by either noradrenaline or adrenaline. 6-Nitrodopamine is the most potent endogenous relaxant agent in RbCC ever described and represents a novel mechanism by which NO causes corpus cavernosum smooth muscle relaxation. The finding that 6-ND acts as a truly selective dopamine D2 -receptor antagonist indicates that the balance of dopamine and 6-ND release/synthesis may be the main mechanism that modulates corpus cavernosum smooth muscle tonus in vivo.

Intravascular hemolysis leads to exaggerated corpus cavernosum relaxation: Implication for priapism in sickle cell disease

Patients with sickle cell disease (SCD) display priapism. Clinical studies have shown a strong positive correlation between priapism and high levels of intravascular hemolysis in men with SCD. However, there are no experimental studies that show that intravascular hemolysis promotes alterations in erectile function. Therefore, we aimed to evaluate the corpus cavernosum smooth muscle relaxant function in a murine model that displays intravascular hemolysis induced by phenylhydrazine (PHZ), as well as the role of intravascular hemolysis in increasing the stress oxidative in the penis. Corpus cavernosum strips were dissected free and placed in organ baths. Acetylcholine and electrical field stimulation (EFS)-induced corpus cavernosum relaxations in vitro were obtained. Increased corpus cavernosum relaxant responses to acetylcholine and EFS were observed in the PHZ group. Protein expression of heme oxygenase-1 increased in the corpus cavernosum of the PHZ group, but PDE5 protein expression was not modified. Preincubation with the heme oxygenase inhibitor 1J completely reversed the increased relaxant responses to acetylcholine and EFS in PHZ mice. Protein expression of NADPH oxidase subunit gp91phox, 3-nitrotyrosine, and 4-hydroxynonenal increased in the corpus cavernosum of the PHZ group, suggesting a state of oxidative stress. Basal cGMP production was lower in the PHZ group. Our results show that intravascular hemolysis promotes increased corpus cavernosum smooth muscle relaxation associated with increased HO-1 expression, as well as increased oxidative stress associated with upregulation of gp91phox expression. Moreover, our study supports clinical studies that point to a strong positive correlation between priapism and high levels of intravascular hemolysis in men with SCD.

MP59-11 INTRACAVERNOSAL MIRCORNA-133B INJECTION PROMOTES ERECTILE FUNCTION IN DIABETIC RATS BY REGULATING THE CONTRACTILITY OF CORPUS CAVERNOSUM SMOOTH MUSCLE

INTRODUCTION AND OBJECTIVES:Cavernosal smooth muscle relaxation is a key composition for normal erection. MicroRNAs (miRs) are noncoding single-stranded RNAs that regulate the expression of genes i...

Expression Profiles of eNOS, iNOS, endothelin receptors and microRNAs‐27b, 155 and 199 in the corpus cavernosum of rats submitted to chronic alcoholism and diabetes mellitus.

IntroductionEthanol consumption has been described to increase the levels of plasma endothelin‐1 (ET‐1) suggesting that chronic consumption activates endothelinergic pathway and also to affect nitric oxide synthase (NOS) derived nitric oxide (NO) and NOS expression in different tissues. Recent evidence showed that chronic ethanol consumption increases ET‐1‐induced sustained contraction of trabecular smooth muscles cells of the corpora cavernosal in corpus cavernosum of rat by mechanism that involves increased expression of ETA eee and ETB receptors.ObjectivesTo evaluate the effects of chronic ethanol consumption associated with diabetes affected the endothelin system in the cavernosal smooth muscle (CSM) of rats, as well as the effects of chronic ethanol consumption and diabetes on nitric oxide (NO)‐mediated relaxation of cavernosal smooth muscle (CSM).Materials and MethodsCorpus cavernosum were divided into four groups: control, ethanol, diabetic and ethanol‐diabetic of Male Wistar rats. We analyzed protein and gene expression of endothelial NO synthase (eNOS), inducible NO synthase (iNOS) and endothelin receptors (ETA eeeand ETB) by immunohistochemistry and real time‐PCR. The expression of miRNAs‐27a, 199 and 155 by real time‐PCR in corpus cavernosum. It was also evaluated the effect of ethanol consumption associated with diabetes on the relaxation induced by acetylcholine (ACh; 0.01–1000 micromol/L) and in the contraction induced by Endothelin‐1 (ET‐1 0.1 nmol‐ 1μmol L‐1) in organ chambers for measurement of isometric tension.ResultsThe endothelium‐dependent relaxation induced by ACh was decreased in CSM from ethanol, diabetic, ethanol‐diabetic groups when compared with the control group. Immunohistochemistry for eNOS, iNOS, ETA eeeand ETB showed an increase in cavernosal smooth muscle cells in the ethanol, diabetic and ethanol‐diabetic groups when compared with the control group. Similarly, the mRNA levels for eNOs, ETA eeeand ETB were increased in CSM of groups ethanol, diabetic and ethanol‐diabetic and miRNAs‐27a, 155 and 199 were decreased in cavernosal smooth muscle from the ethanol, diabetic and ethanol‐diabetic groups.ConclusionsOur results showed that chronic ethanol consumption associated with diabetes was an impairment of relaxation of CSM from ethanol, diabetic, and ethanol‐diabetic rats that involved a decrease in the NO pathway by endothelium‐dependent mechanisms accompanied by a change in the corpus cavernosum contractile sensitivity. We can also suggest that chronic ethanol consumption associated with diabetes changed the endothelinergic system in the CSM played a role in the pathogenesis of erectile dysfunction, suggesting that these changes of endothelin receptors were regulated by miRNAs‐155, 199.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Galanin Administration Partially Restores Erectile Function After Cavernous Nerve Injury and Mediates Endogenous Nitrergic Nerve Outgrowth In Vitro

BackgroundPreviously, we found that the neuropeptide galanin was strongly upregulated soon after bilateral cavernous nerve injury (BCNI) and that galanin and its receptors were expressed in nitrergic erectile innervation. Galanin has been observed to exert neuroregenerative effects in dorsal root ganglion neurons, but evidence for these effects in the major pelvic ganglion (MPG) after BCNI is lacking. AimTo evaluate the neurotropic effects of galanin receptor agonists and antagonists in vitro in nitrergic neurons and MPG and in vivo in rats after BCNI. MethodsMale Sprague-Dawley rats underwent BCNI and sham surgery. Organ culture and single-cell neuron culture of the MPG were performed. Osmotic pump treatment with the galanin agonist in vivo and measurement of erectile response to electrostimulation after BCNI, immunohistochemical localization of galanin and receptors in the human neurovascular bundle, and myographic analysis of rat corpus cavernosum smooth muscle relaxation to galanin receptor agonists were investigated. OutcomesNeurite outgrowth in vitro and erectile response to electrostimulation after BCNI in vivo, immunohistochemical localization of galanin and receptors, and penile muscle relaxation in vitro. ResultsGalanin showed neurotrophic action in vitro and inhibition of endogenous galanin significantly impaired neurite outgrowth in nitrergic but not in sympathetic MPG neurons. In vivo administration of a selective galanin receptor-2 agonist, M1145, resulted in partial recovery of erectile function (EF) after BCNI. Galanin did not act as a direct vasodilator on corpus cavernosum muscle strips. Clinical TranslationEndogenous neurotrophins such as galanin could be used as a strategy to improve EF for patients after BCNI from radical prostatectomy. Strengths and LimitationsWe evaluated the effect of galanin on nerve regeneration and EF recovery in vivo and in vitro. Limitations include the lack of washout period for the in vivo experiment and absence of differences in the expression of neuronal markers between treatment groups. ConclusionsWe identified galanin as a potential endogenous mechanism for nerve regeneration after BCNI, which could play a physiologic role in EF recovery after radical prostatectomy. In vivo treatment with exogenous galanin was beneficial in enhancing EF recovery after BCNI, but further research is necessary to understand the underlying mechanisms.Weyne E, Hannan JL, Gevaert T, et al. Galanin Administration Partially Restores Erectile Function After Cavernous Nerve Injury and Mediates Endogenous Nitrergic Nerve Outgrowth In Vitro. J Sex Med 2018;15:480–491.

In vitro and in vivo aphrodisiac properties of the seed extract from Allium tuberosum on corpus cavernosum smooth muscle relaxation and sexual behavior parameters in male Wistar rats

BackgroundAllium tuberosum is a well-known spice as well as a herb in traditional Chinese medicine, used for increasing libido and treating erectile dysfunction. However, not many studies have been done to evaluate the sexual enhancing properties of A. tuberosum. The aim of this study was to evaluate the aphrodisiac and vasorelaxant properties of A. tuberosum on corpus cavernosum smooth muscle (CCSM) as well as checking the effect on enhancing male rat sexual behavior, libido, potency as well as its spermatogenic properties.MethodThe seeds were powdered and sequentially extracted with hexane, ethyl acetate and butanol. Male Wistar rats were administered with graded doses of the n-BuOH extracts (ATB) of A. tuberosum (50, 100, 200 and 400 mg/kg) and Viagra was used as the positive control drug. The extract/drug was administered by gastric probe once daily for 45 days and the sexual behavior was analyzed by exposing the male rats to female rats in the estrus period.ResultsATB relaxed corpus cavernosum smooth muscle (68.9%) at a concentration of 200 μg/ml. The results obtained from the animal studies indicated that ATB significantly increased mount frequency (MF), intromission frequency (IF), ejaculation frequency (EF), ejaculation latency (EL) and markedly reduced post ejaculatory interval (PEI), mount latency (ML), and intromission latency (IL). Furthermore, a remarkable increase in the test for potency was observed as witnessed by marked increase in erections, quick flips, long flips and total reflex. In addition, ATB significantly improved the sperm viability and count as well as increased the concentrations of testosterone, follicle stimulating hormone (FSH), and phosphatases in the treated animals.ConclusionThus our results suggest that A. tuberosum could stimulate sexual arousal and enhance sexual execution in male rats, thus providing valuable experimental evidence that A. tuberosum possesses sexual enhancing properties.

Expression profiles of eNOS, iNOS and microRNA-27b in the corpus cavernosum of rats submitted to chronic alcoholism and Diabetes mellitus.

To evaluate the expression of endothelial and inducible NOS in addition to the miRNA-27b in the corpus cavernosum and peripheral blood of healthy rats, diabetic rats, alcoholic rats and rats with both pathologies. Forty eight Wistar rats were divided into four groups: control (C), alcoholic (A), diabetic (D) and alcoholic-diabetic (AD). Samples of the corpus cavernosum were prepared to study protein expressions of eNOS and iNOS by immunohistochemistry and expression of miRNA-27b in the corpus cavernosum and peripheral blood. Immunohistochemistry for eNOS and iNOS showed an increase in cavernosal smooth muscle cells in the alcoholic, diabetic and alcoholic-diabetic groups when compared with the control group. Similarly, the mRNA levels for eNOS were increased in cavernosal smooth muscle (CSM) in the alcoholic, diabetic and alcoholic-diabetic groups and miRNA-27b were decreased in CSM in the alcoholic, diabetic and alcoholic-diabetic groups. The major new finding of our study was an impairment of relaxation of cavernosal smooth muscle in alcoholic, diabetic, and alcoholic-diabetic rats that involved a decrease in the nitric oxide pathway by endothelium-dependent mechanisms accompanied by a change in the corpus cavernosum contractile sensitivity.

Sesquiterpene lactones from Hedyosmum brasiliense induce in vitro relaxation of rat aorta and corpus cavernosum

Hedyosmum brasiliense Miq., Chloranthaceae, has been used in Southern Brazil as a sedative, anti-inflammatory, and aphrodisiac. In this study, endothelium-intact and endothelium-denuded rat aortic rings and strips of corpus cavernosum were used to investigate the relaxant effects of an hexane fraction of leaves of H. brasiliense and its sesquiterpene lactones 13-hydroxy-8,9-dehydroshizukanolide, podoandin, and elemanolide 15-acetoxy-isogermafurenolide. The incubation of hexane fraction of leaves of H. brasiliense resulted in significant relaxation of endothelium-intact aortic rings previously contracted by phenylephrine. In addition, 13-hydroxy-8,9-dehydroshizukanolide and podoandin displayed a clear concentration-dependent ability to relax endothelium-intact (∼85 to 90%) and endothelium-denuded (∼45 to 55%) rat aortic rings. A less pronounced vascular relaxation was recorded when 15-hydroxy-isogermafurenolide was tested. Interestingly, in tissues previously incubated with the nitric oxide synthase inhibitor l-NAME (100μM), both 13-hydroxy-8,9-dehydroshizukanolide and podoandin had their effects in endothelium-intact vessels reduced to the same degree of relaxation observed in endothelium-denuded aortic rings. Podoandin, 13-hydroxy-8,9-dehydroshizukanolide, and 15-acetoxy-isogermafurenolide (100μM) were also able to relax precontracted corpus cavernosum strips by 49.5±3.9%, 65.9±7.3% and 57.9±5.5%, respectively. Our results demonstrated that 13-hydroxy-8,9-dehydroshizukanolide, podoandin and 15-acetoxy-isogermafurenolide, isolated from H. brasiliense, generate both endothelium-dependent and -independent relaxation of rat aortic rings, as well as being able to induce in vitro relaxation of rat corpus cavernosum. Importantly, the endothelium-dependent effect is fully dependent on nitric oxide production. Considering that penile erection depends on both relaxation of cavernosal smooth muscle and inflow of blood for the cavernous bodies, this is the first study reporting experimental evidence supporting the aphrodisiac properties of H. brasiliense.

Light-controlled relaxation of the rat penile corpus cavernosum using NOBL-1, a novel nitric oxide releaser.

PurposeTo investigate whether relaxation of the rat penile corpus cavernosum could be controlled with NOBL-1, a novel, light-controllable nitric oxide (NO) releaser.Materials and MethodsFifteen-week-old male Wistar-ST rats were used. The penile corpus cavernosum was prepared and used in an isometric tension study. After noradrenaline (10-5 M) achieved precontraction, the penile corpus cavernosum was irradiated by light (470–500 nm) with and without NOBL-1 (10-6 M). In addition, we noted rats' responses to light with vardenafil (10-6 M), a phosphodiesterase-5 (PDE-5) inhibitor. Next, responses to light in the presence of a guanylate cyclase inhibitor, ODQ (1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one) (10-5 M), were measured. All measurements were performed in pretreated L-NAME (10-4 M) conditions to inhibit endogenous NO production.ResultsCorpus cavernosal smooth muscle, precontracted with noradrenaline, was unchanged by light irradiation in the absence of NOBL-1. However, in the presence of NOBL-1, corpus cavernosal smooth muscle, precontracted with noradrenaline, relaxed in response to light irradiation. After blue light irradiation ceased, tension returned. In addition, the light response was obviously enhanced in the presence of a PDE-5 inhibitor.ConclusionsThis study showed that rat corpus cavernosal smooth muscle relaxation can be light-controlled using NOBL-1, a novel, light sensitive NO releaser. Though further in vivo studies are needed to investigate possible usefulness, NOBL-1 may be prove to be a useful tool for erectile dysfunction therapy, specifically in the field of penile rehabilitation.

Flibanserin for Low Sexual Desire in Women: A Molecule From Bench to Bed?

Flibanserin for Low Sexual Desire in Women: A Molecule From Bench to Bed?

Effects of insulin-like growth factor-1 on the relaxation responses of the cavernous smooth muscle from aged rats

Objective. The aim of this study was determine whether intracavernosal injection (ICI) of insulin-like growth factor-1 (IGF-1) protein can improve corpus cavernosal smooth muscle relaxation in aging rats. Materials and methods. Ten young (4-month-old) and 30 old (24-month-old) Sprague–Dawley male rats were enrolled in the study. The old rats were divided into three groups: vehicle-only (n = 10), IGF-1 1 µg/kg (n = 10) and IGF-1 10 µg/kg treatment groups (n = 10). After 4 weeks of single IGF-1 injection treatment, strips of corporal tissue were precontracted with phenylephrine, and dose–response curves were generated to evaluate endothelial-dependent [acetylcholine (ACh)], endothelial-independent [sodium nitroprusside (SNP)] and electrical field stimulation (EFS) vasoreactivity. The changes in percentage of cavernosal smooth muscle and the concentration of nitric oxide (NO) in penile tissue were also evaluated. Results. After IGF-1 treatment, the vasoreactivity was significantly improved in both the 1 µg/kg and the 10 µg/kg treatment groups compared with the vehicle-only group at 4 weeks in response to ACh, SNP and EFS (all p < 0.05). The percentage of cavernosal smooth muscle was increased in the IGF-1 treatment groups. The NO concentrations were increased after IGF-1 treatment. Conclusions. These data demonstrate that ICI of IGF-1 can improve vasoreactivity via endothelium-dependent and endothelial-independent mechanisms in the corpus cavernosum of the aging rat.

Long-term testosterone supplementation is useful for ED with testosterone deficiency

Long-term testosterone supplementation is useful for ED with testosterone deficiency

In vitro and in vivo aphrodisiac properties of Corchorus depressus Linn. on rabbit corpus cavernosum smooth muscle relaxation and sexual behavior of normal male rats

Ethnopharmacological relevanceCorchorus depressus Linn. has been used as an aphrodisiac in traditional Indian medicine to treat male sexual dysfunction and impotency. Aim of the studyThe petroleum ether, chloroform, ethyl acetate, n-butanol and aqueous fractions of 95% methanol extract of Corchorus depressus were screened initially for their in vitro aphrodisiac activity on rabbit corpus cavernosum smooth muscle. The chloroform fraction (CDC) was found to be the most active and therefore investigated further on general mating behavior, libido and potency of normal male Wistar albino rats in comparison with the standard drug, Sildenafil citrate. Materials and methodsAnimals were divided into the following groups: Control, SC CDC 100, CDC 200, and CDC 400, who received saline, Sildenafil citrate or the chloroform fraction of Corchorus depressus at doses of 100, 200 or 400mg/kg b.wt., respectively. The route of administration for all the groups was oral dosing, which was once in a day for 45 days. To analyze the mating behavior, female rats with estrus phase were used. ResultsThe chloroform fraction of methanolic extract of Corchorus depressus significantly reduced ML, IL, PEI and III. There was a significant increase in the MF, IF and EL and serum testosterone levels throughout the study period. The potency test significantly increased erections, quick flips, long flips and total reflex. In vitro aphrodisiac activity was significantly higher in chloroform fraction at a concentration of 25.0mg/ml, which induced 71.4% relaxation. The combined results of the above mentioned models indicate that the chloroform fraction of Corchorus depressus produces a significant increase in sexual activity as exhibited by 25mg/ml in vitro and 400mg/kg in vivo. In comparison with the control, all the drug-treated groups have shown drug-induced effects for a few parameters. ConclusionsIn vitro and in vivo studies provide valuable experimental evidence that the chloroform fraction of methanolic extract of Corchorus depressus possesses aphrodisiac property. This study further substantiates the ethnopharmacological claims of Corchorus depressus as a sexual stimulating agent and offers a significant potential for studying the effect on male sexual response and its dysfunctions.

Excessive Penile Norepinephrine Level Underlies Impaired Erectile Function in Adenosine A1 Receptor Deficient Mice

Penile erection is a complex neurovascular physiological event controlled by multiple factors and signaling pathways. A considerable amount of evidence indicates that adenosine plays a significant role in cavernosal smooth muscle relaxation. However, the specific role of adenosine and its receptors in erectile physiology and pathology is not fully understood. To determine the role of the adenosine A1 receptor (ADORA1) in penile erection. Adenosine A1 receptor deficient (Adora1-/-) mice and aged-matched wild-type (WT) mice were utilized. We evaluated the in vivo erectile function by measuring the intracavernosal pressure (ICP) in response to cavernous nerve stimulation (CNS). Enzyme-linked immunosorbent assay was used to measure the norepinephrine (NE) plasma concentration in the corpus cavernosum and systemic circulation. We also evaluated the myosin light chain phosphorylation (p-MLC) in penile tissue pre- and post-CNS. The main outcome measurement of this research was the evaluation of in vivo erectile response to CNS by measuring the ICP in Adora1-/- mice and WT mice and to identify the localization and specific neuron types of ADORA1 expression by dual immunostaining and immunofluorescence co-localization. In vivo, both the ratio of CNS-induced Maximum ICP to mean arterial pressure and CNS-induced slope in Adora1-/- mice were significantly lower than WT mice. At the cellular level in penile tissue, we determined that ADORA1 was highly abundant in neuronal cells. During penile erection, Adora1-/- mice exhibited a higher level of NE plasma concentration in the penis than WT mice. And WT mice had a significantly greater reduction in p-MLC compared to Adora1-/- mice. Our results show that ADORA1 is enriched on neuron cells where it functions to control NE release. Activation of this receptor during penile erection results in reduced NE release and reduced cavernosal smooth muscle contraction, therefore facilitating penile erection.

Butea superba (Roxb.) improves penile erection in diabetic rats

The objective of the present study was to investigate the effect of ethanolic extract of Butea superba (Roxb.) on erectile dysfunction in diabetic rats by the measurement of intracavernous pressure (ICP) and on cavernosal smooth muscle relaxation. Male Sprague-Dawley rats were induced to become diabetic by a single intravenous injection of Streptozotocin (55 mg kg(-1) body weight). The ethanolic extract at the concentration of 1, 10 and 100 mg kg(-1) BW was administered orally once a day to diabetic rats in each group for 4 weeks. Diabetic rats showed a significant decrease in both ICP and the relaxation of the cavernosal smooth muscle compared with the normal rats. The extract of B. superba significantly increased the ICP with the effective dose of 10 mg kg(-1) BW (61.00 ± 11.11 mmHg versus 39.61 ± 11.01 mmHg in the diabetic control group). Moreover, the B. superba-treated group also showed enhanced relaxation of the cavernosal smooth muscle with EC(50) of 1.17 mg ml(-1). These results suggest that the extract of B. superba enhanced penile erection in diabetic rats by increasing the ICP. This might be explained by the increased blood flow as a result of the relaxation of the cavernous smooth muscle.

Corpus Cavernosal Smooth Muscle Relaxation Effect of a Novel AMPK Activator, Beta‐Lapachone

Adenosine monophosphate-activated protein kinase (AMPK) activation is suggested to relax smooth muscle by endothelial nitric oxide synthase (eNOS) phosphorylation. To assess the mechanism and effect of a novel AMPK activator, beta-lapachone, upon cavernosal smooth muscle relaxation and the therapeutic potential for erectile dysfunction. Human umbilical vein endothelial cells (HUVECs) were treated with beta-lapachone. The lysates were blotted with specific antibodies for phosphorylated AMPK (p-AMPK) or phosphorylated eNOS (p-eNOS). The membranes were re-blotted for total AMP total eNOS, or beta-actin. The eNOS activity was measured by the conversion of L-14C-arginine to L-14C-citrulline in HUVECs lysates. In a separated experiment, cavernosal strips from New Zealand white rabbits were harvested for organ bath study and the relaxation effect of beta-lapachone on phenylephrine-induced contracted strips was evaluated and compared with sodium nitroprusside, zaprinast, metformin, and aminoimidazole carboxamide ribonucleotide (AICAR). Methylene blue and L-NAME were used to assess the inhibition of cyclic guanosine monophosphate/nitric oxide pathway. Zinc-protoporphyrin-IX (ZnPP) was also used to investigate the contribution of mevalonate pathway. The expression of p-AMPK, p-eNOS, AMPK and eNOS induced by beta-lapachone in HUVECs study and the percent relaxation of cavernosal tissue in organ bath study. Beta-lapachone clearly induced AMPK phosphorylation and, as a consequence, eNOS phosphorylation in HUVECs. Beta-lapachone-induced upregulation of eNOS activity was also observed in HUVECs and steadily increased up to 1 hour. In organ bath study, beta-lapachone significantly relaxed the phenylephrine pretreated strips in a dose-dependent manner. This relaxation effect was not totally blocked by methylene blue or L-NAME. After removing endothelium, the relaxation was totally blocked by ZnPP. A novel AMPK activator, beta-lapachone has a strong relaxation effect on precontracted cavernosal smooth muscle strips in the rabbit. And phosphorylation of AMPK and eNOS strongly related to the action of beta-lapachone. Mevalonate pathway also might be considered as a suggestive mechanism.

Effects of Ginkgo biloba extracts with mirodenafil on the relaxation of corpus cavernosal smooth muscle and the potassium channel activity of corporal smooth muscle cells

In this study, we investigated the effects of a combination of Ginkgo biloba extracts (GBE) and phosphodiesterase type 5 (PDE-5) inhibitors on the muscular tone of the corpus cavernosum and potassium channel activity of corporal smooth muscle cells. Strips of corpus cavernosum from male New Zealand white rabbits were mounted in organ baths for isometric tension studies. After contraction with 1×10⁻⁵ mol l⁻¹ norepinephrine, GBE (0.01-1 mg ml⁻¹) and mirodenafil (0.01-100 nmol l⁻¹) were added together into the organ bath. In electrophysiological studies, whole-cell currents were recorded by the conventional patch-clamp technique in cultured smooth muscle cells of the human corpus cavernosum. The corpus cavernosum was relaxed in response to GBE in a dose-dependent manner (from 0.64%±8.35% at 0.01 mg ml⁻¹ to 52.28% ± 11.42% at 1 mg ml⁻¹). After pre-treatment with 0.03 mg ml⁻¹ of GBE, the relaxant effects of mirodenafil were increased at all concentrations. After tetraethylammonium (TEA) (1 mmol l⁻¹) administration, the increased effects were inhibited (P<0.01). Extracellular administration of GBE increased the whole-cell K(+) outward currents in a dose-dependent fashion. The increase of the outward current was inhibited by 1 mmol l⁻¹ TEA. These results suggest that GBE could increase the relaxant potency of mirodenafil even at a minimally effective dose. The K(+) flow through potassium channels might be one of the mechanisms involved in this synergistic relaxation.

Experimental model of human corpus cavernosum smooth muscle relaxation

To describe a technique for en bloc harvesting of the corpus cavernosum, cavernous artery and urethra from transplant organ donors and contraction-relaxation experiments with corpus cavernosum smooth muscle. The corpus cavernosum was dissected to the point of attachment with the crus penis. A 3 cm segment (corpus cavernosum and urethra) was isolated and placed in ice-cold sterile transportation buffer. Under magnification, the cavernous artery was dissected. Thus, 2 cm fragments of cavernous artery and corpus cavernosum were obtained. Strips measuring 3 x 3 x 8 mm(3) were then mounted vertically in an isolated organ bath device. Contractions were measured isometrically with a Narco-Biosystems force displacement transducer (model F-60, Narco-Biosystems, Houston, TX, USA) and recorded on a 4-channel Narco-Biosystems desk model polygraph. Phenylephrine (1 microM) was used to induce tonic contractions in the corpus cavernosum (3-5 g tension) and cavernous artery (0.5-1 g tension) until reaching a plateau. After precontraction, smooth muscle relaxants were used to produce relaxation-response curves (10(-12) M to 10(-4) M). Sodium nitroprusside was used as a relaxation control. The harvesting technique and the smooth muscle contraction-relaxation model described in this study were shown to be useful instruments in the search for new drugs for the treatment of human erectile dysfunction.

Chronic alcoholism associated with diabetes impairs erectile function in rats

To investigate the effects of chronic ethanol consumption and diabetes on nitric oxide (NO)-mediated relaxation of cavernosal smooth muscle (CSM). Male Wistar rats were divided into four groups: control, isocaloric, diabetic and ethanol-diabetic. The CSMs were mounted in organ chambers for measurement of isometric tension. Contraction of the strips was induced by electrical field stimulation (EFS, 1-32 Hz) and phenylephrine. We also evaluated the effect of ethanol consumption on the relaxation induced by acetylcholine (ACh; 0.01-1000 micromol/L), sodium nitroprusside (SNP, 0.01-1000 micromol/L) or EFS (1-32 Hz) in strips pre-contracted with phenylephrine (10 micromol/L). Immunoexpression of endothelial NO synthase (eNOS) and inducible NOS (iNOS) was also accessed. The endothelium-dependent relaxation induced by ACh was decreased in CSM from ethanol-diabetic rats when compared with the controls, with a mean (sem) of 21 (4) vs 37 (2)%. Similarly, the potency and maximal responses induced by SNP were reduced in the ethanol-diabetic [3.97 (0.38) and 85 (1)%, respectively] and diabetic groups [3.78 (0.56) and 81 (2)%, respectively] when compared with the controls [5.3 (0.22) and 90 (3)%, respectively] and isocaloric [5.3 (0.19) and 92 (1)%, respectively] groups. Noradrenergic nerve-mediated contractions of CSM in response to EFS were increased in rats from ethanol-diabetic and diabetic groups when compared with the control and isocaloric groups. Conversely, there were no differences in EFS-induced relaxation among the groups. The immunostaining assays showed overexpression of eNOS and iNOS in the CSM from diabetic and ethanol-diabetic rats when compared with the control and isocaloric rats. There was an impairment of relaxation of CSM from ethanol-diabetic and diabetic rats that involved a decrease in the NO-cyclic guanosine monophosphate signalling pathway by endothelium-dependent mechanisms accompanied by a change in the CSM contractile sensitivity.

875 RESVERATROL, A POLYPHENOLIC SIRT1 ACTIVATOR, IMPROVES ERECTILE FUNCTION IN STREPTOZOTOCIN INDUCED DIABETIC RATS

You have accessJournal of UrologySexual Function/Dysfunction/Andrology: Basic Research II1 Apr 2010875 RESVERATROL, A POLYPHENOLIC SIRT1 ACTIVATOR, IMPROVES ERECTILE FUNCTION IN STREPTOZOTOCIN INDUCED DIABETIC RATS Shinichiro Fukuhara, Hidenobu Okuda, Keisuke Yamamoto, Jiro Nakayama, Tetsuya Takao, Yasushi Miyagawa, Akira Tsujimura, Norio Nonomura, and Akihiko Okuyama Shinichiro FukuharaShinichiro Fukuhara More articles by this author , Hidenobu OkudaHidenobu Okuda More articles by this author , Keisuke YamamotoKeisuke Yamamoto More articles by this author , Jiro NakayamaJiro Nakayama More articles by this author , Tetsuya TakaoTetsuya Takao More articles by this author , Yasushi MiyagawaYasushi Miyagawa More articles by this author , Akira TsujimuraAkira Tsujimura More articles by this author , Norio NonomuraNorio Nonomura More articles by this author , and Akihiko OkuyamaAkihiko Okuyama More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2010.02.1631AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES SIRT1 is an important enzyme for many cellular processes including cell cycle regulation, fatty acid metabolism, and life span extension. Recently, it has been reported that SIRT1 promotes endothelium-dependent vascular relaxation by activating endothelial nitric oxide synthase (eNOS) in endothelial cells, however its effect on corpus cavernosal smooth muscle relaxation remain poorly defined. Resveratrol is a polyphenolic compound, and has been reported to be an activator of SIRT1. Therefore, we investigated the effects of resveratrol on NO/cGMP pathway in human corpus cavernosal smooth muscle cells (CCSMCs) which were shown to express eNOS and synthesize NO in our previous report, and its therapeutic potential for erectile dysfunction in diabetic rats. We also examined the hypothesis that a combination of SIRT1 activation and phosphodiesterase 5 (PDE5) inhibition has synergistic effect in vitro and vivo. METHODS We measured intraceller cGMP concentration after incubation of human CCSMCs with resveratrol, PDE5 inhibitor (vardenafil), and both. In addition, to eliminate possible nonspecific effects, the cells were also incubated with sirtinol which inhibit SIRT1. Then, to investigate erectile function, four weeks after establishment of diabetes due to streptozotocin injection (50mg/kg i.p), rats treated with either only vehicle, PDE5 inhibitor (vardenafil 0.5m/kg/day p.o), resveratrol (5mg/kg/day p.o) or resveratrol plus PDE5 inhibitor. After four weeks treatment, the intracavernosal pressure (ICP) with electrical stimulation to the cavernous nerve and mean arterial pressure (MAP) were measured. RESULTS The levels of cGMP in human CCSMCs were significantly increased either by administration of PDE5 inhibitor or resveratrol compare with those of controls. A drastic synergistic increase in cGMP was observed when treated with both PDE5 inhibitor and resveratorol simultaneously. Furthermore, the effects of resveratrol on cGMP synthesis were reversed by sirtinol a specific SIRT1 inhibitor. In vivo experiments, while the ICP/MAP was significantly lower in treated with only vehicle rats, ICP/MAP in treated with resveratrol rats showed significantly higher. And more, The ICP/MAP in treated with both agents was higher than all other groups. CONCLUSIONS Resveratorol leads to enhancement of cGMP synthesis in human CCSMSs and improves erectile function in storeptozotocin induced diabetic rats, particularly with PDE5 inhibitor. Our data indicate that resveratrol has therapeutic potential for diabetic erectile dysfunction. Suita, Japan© 2010 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 183Issue 4SApril 2010Page: e342 Advertisement Copyright & Permissions© 2010 by American Urological Association Education and Research, Inc.MetricsAuthor Information Shinichiro Fukuhara More articles by this author Hidenobu Okuda More articles by this author Keisuke Yamamoto More articles by this author Jiro Nakayama More articles by this author Tetsuya Takao More articles by this author Yasushi Miyagawa More articles by this author Akira Tsujimura More articles by this author Norio Nonomura More articles by this author Akihiko Okuyama More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...