DOCSLIB.ORG

Vasoconstriction, Rhoa/Rho-Kinase and the Erectile Response

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Vasoconstriction, Rhoa/Rho-Kinase and the Erectile Response International Journal of Impotence Research (2003) 15, Suppl 5, S20–S24 & 2003 Nature Publishing Group All rights reserved 0955-9930/03 $25.00 www.nature.com/ijir Vasoconstriction, RhoA/Rho-kinase and the erectile response TM Mills1,2*, RW Lewis2, CJ Wingard1,2, AE Linder1, L Jin1 and RC Webb1,2 1Department of Physiology, Medical College of Georgia, Augusta, Georgia, USA; and 2Department of Surgery (Urology), Medical College of Georgia, Augusta, Georgia, USA Recent studies have suggested that contraction of the smooth muscle in the cavernosal arterioles and in the walls of the cavernosal sinuses is maintained by the RhoA/Rho-kinase signaling pathway. However, this contraction activity must be overcome to permit the vasorelaxation essential for erection. We postulate that nitric oxide (NO) causes erection primarily by inhibiting the RhoA/Rho-kinase pathway. The following will discuss evidence in support of the important role of Rho-kinase-mediated vasoconstriction in the nonerect penis and how NO overrides this Rho- kinase-mediated vasoconstriction to permit vasodilation and erection. International Journal of Impotence Research (2003) 15, Suppl 5, S20–S24. doi:10.1038/sj.ijir.3901068 Keywords: penile erection; nitric oxide; Rho-kinase Introduction which are lined with endothelial cells (sinusoidal endothelial cells) and contains smooth muscle (sinusoidal smooth muscle) in their walls. Blood is The majority of the time, the smooth muscle cells in conveyed out of the sinuses via the thin-walled the erectile tissue remain contracted and blood flow veins lying immediately beneath the tunica albugi- into the cavernous sinuses is minimal. Studies from nea (subtunical veins). The cavernosal arterioles several laboratories strongly support the concept also containing endothelial cells overlie layers of that RhoA/Rho-kinase-mediated vasoconstriction is smooth muscle cells. When the arteriolar smooth primarily responsible for keeping penile smooth muscle layer is contracted, only small volumes of 1–5 muscle in the contracted state. Nitric oxide (NO), blood are delivered to the sinuses and this volume is released by autonomic innervation and by endothe- readily drained out through the subtunical veins. lial cells leads to increased production of cGMP and Thus, the contraction of arteriolar and sinusoidal activation of protein kinase G (PKG). We have smooth muscle limits blood flow into the erectile proposed that the NO/cGMP/PKG pathway inhibits tissue and keeps the penis in the nonerect state. In RhoA/Rho-kinase-mediated vasoconstriction allow- order for erection to occur, the smooth muscle in the ing smooth muscle relaxation and the increased arterioles and cavernous sinuses must relax. As the blood flow required for erection. arterioles relax, blood flow into the cavernous sinuses increases and exert shear and stretch force on the sinusoidal endothelial cells. The endothelial Erectile physiology6 cells respond with the activation of eNOS activity and the release of additional NO which also contributes to smooth muscle relaxation. As the Erectile tissue is housed in the two dorsal corpora sinusoidal smooth muscle relaxes, the sinuses cavernosa and the single ventral corpus spongiosum expand against the tunica albuginea and blood of the penis. Since the spongiosum contributes little outflow decreases (veno-occlusion). The increased to the rigidity during erection, it will not be further inflow and decreased outflow result in the high discussed. The corpora cavernosa contain connec- intracavernosal pressures which are characteristics tive tissue arranged in a trabecular meshwork which of the erect penis. is continuous with the tunica albuginea. This meshwork limits the system of vascular sinuses VasoconstrictionFmaintenance of the penis in the flaccid state *Correspondence: TM Mills, Department of Physiology, Medical College of Georgia, Augusta, GA 30912-3000, USA. The following contains a brief review of the E-mail: [email protected] pharmacology of penile erection with emphasis Erectile response TM Mills et al S21 placed on the role of the RhoA/Rho-kinase calcium inhibiting L-type Ca2+ channels, (2) activating sensitization pathway. A more general description of Ca2+-dependent ATPase in the sarcoplasmic reticu- penile pharmacology can be found in several recent lum and/or (3) hyperpolarizing the cell membrane reviews.6–9 The penis is held in the nonerect state by causing increased opening of membrane K+ except during periods of sexual excitement and channels.20 during nocturnal penile tumescence events (non- sexual erections that occur during sleep). The contraction of penile smooth muscle appears to be mediated by the actions of a-adrenergic agonists and RhoA/Rho-kinase calcium sensitization pathway (Figure 1) by the actions of endothelin-1 acting via ETA 8,10,11 receptors. The physiology of the ETB receptors in penile erection remains less clear.12 In other 13 While there is ample conceptual support for the vascular systems, binding of ET-1 to the ETB importance of intracellular calcium in regulating receptors in the endothelial cells activates endothe- 13 vasoconstriction and vasodilation in the penile lial NO synthesis and smooth muscle relaxation, vasculature, Ca2+-sensitization has only recently but this has not been extensively studied in penile been investigated in the erectile response. In other tissue. vascular tissues, Ca2+-sensitization is, in part, The initial contraction of vascular smooth muscle dependent on enzymes of the RhoA/Rho-kinase depends on elevated intracellular levels of cytosolic 14,16,19 2+ pathway. RhoA is a small, GTP-binding free calcium ([Ca ]i) which occur when ligand protein that is involved in several cellular processes binding leads to the opening of membrane Ca2+ 2+ such as morphology, cytoskeletal function, secretion channels and the release of intracellular Ca 14 14 2+ and smooth muscle contraction. When RhoA is stores. The intracellular Ca complexes with bound to GDP, it is inactive, but with heterotrimeric calmodulin, the complex binds to myosin light G-protein activation (from ligand binding), the GDP chain kinase (MLCK) resulting in its activation. is exchanged for GTP. The RhoA-GTP undergoes When active, MLCK phosphorylates MLC permit- post-translational geranylgeranylation and migra- ting cross bridge formation and contraction. Besides tion to the cell membrane in an active form. The this Ca2+-dependent contractile mechanism, there 2+ process of activation of RhoA is regulated by three is also evidence for a Ca -independent mechanism groups of proteins: guanine nucleotide dissociation operating to maintain smooth muscle contraction. inhibitors (GDI) inhibits RhoA activation, guanine This mechanism was suggested based on the nucleotide exchange factors (GEF) which promote observation that a simple relationship between 2+ the exchange of GDP for GTP to activate RhoA and [Ca ]i and agonist-induced force generation does GTPase associated proteins (GAP) which promote not necessarily exist in vascular smooth muscle intrinsic GTPase activity to inhibit RhoA activation. cells.15 Agonist stimulation results in a transitory 2+ Theoretically, factors that disrupt RhoA activation rise in calcium but [Ca ]i falls to near prestimula- altering the activity of any of these proteins, by tion levels even in the continued presence of the agonist and force generation. These experiments 2+ demonstrate that besides increasing [Ca ]i in a transient fashion, vasoconstrictor agents may in- RHOA~GDP 2+ (INACTIVE) crease the Ca sensitivity of the contractile appa- BINDS GTP 2+ ratus. The Ca sensitization likely involves the MODIFICATIONS RhoA/Rho-kinase regulation of MLC phosphatase MIGRATES TO MEMBRANE 16 RHOA~GTP activity. (ACTIVE) MLC + RHO-KINASE (RELAXATION) +ATP Vasorelaxation and erection of the penis MLC KINASE MLC PHOSPHATASE MLC PHOSPHATASE~P (ACTIVE) (INACTIVE) The penis becomes erect with the relaxation of MLC ~P 7,17 PHOSPHATASE arteriolar and sinusoidal smooth muscle. The (CONTRACTION) PHOSPHATASE (?) principle agent leading to penile smooth muscle Figure 1 The RhoA/Rho-kinase pathway in the maintenance of relaxation is NO released by the autonomic innerva- smooth muscle contraction. RhoA is activated when it binds GTP, tion of the erectile tissue and by arteriolar and undergoes geranylgeranylation and migrates to the cell mem- 18 cavernosal endothelial cells. NO diffuses into brane. Activated RhoA activates Rho-kinase which catalyzes the smooth muscle cells where it activates soluble phosphorylation (and inactivation) of MLC phosphatase. When guanylate cyclase elevating intracellular levels of MLC phosphatase is in the active form (ie, nonphosphorylated), it catalyzes the dephosphorylation of MLC and thereby promotes cyclic GMP and activating cyclic GMP-dependent 19 smooth muscle relaxation. In the penile circulation, smooth protein kinase (PKG). The NO/cGMP/PKG path- muscle relaxation leads to increased intracavernosal blood way is thought to reduce contractile activity by: (1) pressure and erection. International Journal of Impotence Research Erectile response TM Mills et al S22 preventing geranylgeranylation or blocking migra- cavernous tissue were contracted with phenylephr- tion would block smooth muscle contraction and ine or endothelin-1 and then caused to relax in a allow relaxation. Activated RhoA has a variety of dose-dependent fashion with the addition of Y- downstream targets, but in penile smooth muscle, 27632.3,4,21,22 Based on these in vivo and in vitro the target of interest is
Load more

Recommended publications
  • The Cyclist's Vulva
    The Cyclist’s Vulva Dr. Chimsom T. Oleka, MD FACOG Board Certified OBGYN Fellowship Trained Pediatric and Adolescent Gynecologist National Medical Network –USOPC Houston, TX DEPARTMENT NAME DISCLOSURES None [email protected] DEPARTMENT NAME PRONOUNS The use of “female” and “woman” in this talk, as well as in the highlighted studies refer to cis gender females with vulvas DEPARTMENT NAME GOALS To highlight an issue To discuss why this issue matters To inspire future research and exploration To normalize the conversation DEPARTMENT NAME The consensus is that when you first start cycling on your good‐as‐new, unbruised foof, it is going to hurt. After a “breaking‐in” period, the pain‐to‐numbness ratio becomes favourable. As long as you protect against infection, wear padded shorts with a generous layer of chamois cream, no underwear and make regular offerings to the ingrown hair goddess, things are manageable. This is wrong. Hannah Dines British T2 trike rider who competed at the 2016 Summer Paralympics DEPARTMENT NAME MY INTRODUCTION TO CYCLING Childhood Adolescence Adult Life DEPARTMENT NAME THE CYCLIST’S VULVA The Issue Vulva Anatomy Vulva Trauma Prevention DEPARTMENT NAME CYCLING HAS POSITIVE BENEFITS Popular Means of Exercise Has gained popularity among Ideal nonimpact women in the past aerobic exercise decade Increases Lowers all cause cardiorespiratory mortality risks fitness DEPARTMENT NAME Hermans TJN, Wijn RPWF, Winkens B, et al. Urogenital and Sexual complaints in female club cyclists‐a cross‐sectional study. J Sex Med 2016 CYCLING ALSO PREDISPOSES TO VULVAR TRAUMA • Significant decreases in pudendal nerve sensory function in women cyclists • Similar to men, women cyclists suffer from compression injuries that compromise normal function of the main neurovascular bundle of the vulva • Buller et al.
    [Show full text]
  • Anatomy and Physiology of Erection: Pathophysiology of Erectile Dysfunction
    International Journal of Impotence Research (2003) 15, Suppl 7, S5–S8 & 2003 Nature Publishing Group All rights reserved 0955-9930/03 $25.00 www.nature.com/ijir Chapter 2 Anatomy and Physiology of erection: pathophysiology of erectile dysfunction Reporters and participants of the 1st Latin American Dysfunction Consensus Meeting International Journal of Impotence Research (2003) 15, Suppl 7, S5–S8. doi:10.1038/sj.ijir.3901127 Anatomy deep dorsal vein, the circumflex veins, the emissary veins, the cavernous veins and the crural veins). The lacunar spaces drain into small venules, which flow The penis, the male genital organ, has two func- together into a subalbugineal plexus, which in turn, tions: sexual and urinary. It is located above the emerges as emissary veins4,5 (Figure 1). scrotum, and it is linked to the pubic symphysis by two ligaments. It has a three-cylinder shape, integrated by two CROSS-SECTIONAL SECTION OF THE PENIS vascular tissue bodies (corpora cavernosa) (CC) and Superficial dorsal vein the corpus spongiosum (CS). The CCs have two Dorsal artery of penis Dorsal nerve of portions: a fixed posterior one, or perineal, and one penis that is anterior or free. At its base, the ischiopubic Deep dorsal vein Colles’ fascia rami are fixed, surrounded by the ischiocavernous muscles. The CS, in turn, stems from the perineum, Buck’s fascia Circumflex Vein surrounded by the bulbocavernous muscle. The Corpus urethra runs most of its length. At the distal end, cavernosum Tunica albuginea the CS dilates into a structure known as glans, Cavernous artery where the urethra opens to the outside of the Corpus spongiosum Urethral artery body through the meatus.1,2 Urethra Adapted and Modified from the 2ndBrazilian Consensus on Erectile Dysfunction2 The penis has an epidermal layer, underneath which is located the superficial fascia (Colles’), Figure 1 Cross-sectional section of the penis.
    [Show full text]
  • Vestibular Bulb Hypertrophy
    Bahar 1367 Medical Journal of Th� Sh,lahan l..j.()� l;lamic Rcpuhlic of Iran �pnng 19:-;;-; VESTIBULAR BULB HYPERTROPHY H. DABIRASHRAFI,M.H. KARIMINE1AD.Y. BEH1ATNIA, AND N. MOGHDAMI TABRIZI Fromlhe [)eI'{{r/I1l(,lll 0/( )/J.I/e[riCl alld Gynccologv, MirzaKOllchek Khan (Zanan) Hospital. Tehran University of Medical Sciences, Tehran, Islamic Republic of fran ABSTRACT In this case report, a 36 year old female at 40 weeks' gestation is presented in whom large bilateral vestibular bulb masses were found on pelvic examination. The size of the masses was such as to cause concern that they may pose an impediment to normal parturition. Our pathological findings, management and results are presented. MllRI, Vol.2, No.1, 71-73,1988 INTRODUCTION Although cysts of the vagina and vulva are seen rather frequently. only on exceptional occasions does one encounter them in pregnant women and of a sufficient size to interfere with delivery. Spitzer' reported a very interesting and unusual case in which a cyst of Gartner's duct caused a face presenta­ tion. A more common conditiOli is an abscess of the Bartholin gland.' Venereal warts (condylomata) may reach a large size in pregnancy. but seldom to the extent of causing an obstruction.' We report a case of vestibu­ lar bulb tumors that raised concern in that they may obstruct delivery. Downloaded from mjiri.iums.ac.ir at 23:57 IRST on Thursday September 30th 2021 CASE REPORT t A36 year old white woman. G = 7. P = 6. Ah = ()was admitted to the hospital in active true lahor at 4() weeks of gestation.
    [Show full text]
  • A Guide to Clitoral
    A guide to clitoral sex Text Sandra Dahlén English translation Tom Ellett for Exacta översättningar AB Layout and illustrations Eva Fallström Cover photo Maria Gullmark Tryckeri EO Grafiska december 2008 ISBN 978-91-85188-36-9 rfsu • a guide to clitoral sex The clitoris Many people, both scientists and individuals, proud- ly claim to have ‘‘discovered’’ the clitoris. For a long time, the clitoris seems to have been regarded as the principal and most obvious female sex organ, but at some point in the 19th century this focus on the clitoris disappeared in favour of the vagina. Female sexuality was increasingly associated with child-bea- ring, and the clitoris was largely obliterated from the sexual map. In 1905, however, the clitoris was offi- cially ‘‘rediscovered’’ by Sigmund Freud. Freud also put the female orgasm back under the spotlight, be- lieving there were two kinds of orgasm: clitoral and vaginal. The vaginal orgasm, in Freud’s view, was the ‘‘mature’’ and desirable kind. Since the mid 20th cen- tury researchers and activists, mainly from the Uni- ted States and Australia, have been working to gain • • rfsu • a guide to clitoral sex renewed recognition of the importance of the clitoris to female sexuality. For most girls and women, the clitoris is the most important body part in terms of sexual pleasure. Parts of the clitoris The clitoris forms part of the vulva, the external ge- nitalia of a woman. The clitoris is a piece of erectile tissue, rich in nerve endings and blood vessels, and consists of various parts. Where the inner labia meet at the top, there is a foreskin, the prepuce or clitoral hood, covering the clitoral glans or head.
    [Show full text]
  • Anatomy and Physiology of the Clitoris, Vestibular Bulbs, and Labia Minora with a Review of the Female Orgasm and the Prevention of Female Sexual Dysfunction
    Clinical Anatomy 26:134–152 (2013) REVIEW Anatomy and Physiology of the Clitoris, Vestibular Bulbs, and Labia Minora With a Review of the Female Orgasm and the Prevention of Female Sexual Dysfunction VINCENZO PUPPO* Centro Italiano di Sessuologia (CIS), Via Regnoli 74, Bologna, Italy This review, with 21 figures and 1 video, aims to clarify some important aspects of the anatomy and physiology of the female erectile organs (triggers of orgasm), which are important for the prevention of female sexual dysfunction. The clitoris is the homologue of the male’s glans and corpora cavernosa, and erection is reached in three phases: latent, turgid, and rigid. The vestibular bulbs cause ‘‘vaginal’’ orgasmic contractions, through the rhythmic contraction of the bulbocavernosus muscles. Because of the engorgement with blood during sexual arousal, the labia minora become turgid, doubling or tripling in thickness. The corpus spongiosum of thefemaleurethrabecomescongestedduring sexual arousal; therefore, male erection equals erection of the female erectile organs. The correct anatomical term to describe the erectile tissues responsible for female orgasm is the female penis. Vaginal orgasm and the G-spot do not exist. These claims are found in numerous articles that have been written by Addiego F, Whipple B, Jannini E, Buisson O, O’Connell H, Brody S, Ostrzenski A, and others, have no scientific basis. Orgasm is an intense sensation of pleasure achieved by stimulation of erogenous zones. Women do not have a refractory period after each orgasm and can, therefore, ex- perience multiple orgasms. Clitoral sexual response and the female orgasm are not affected by aging. Sexologists should define having sex/love making when orgasm occurs for both partners with or without vaginal intercourse.
    [Show full text]
  • Vasculogenic Female Sexual Dysfunction: the Hemodynamic Basis for Vaginal Engorgement Insuf®Ciency and Clitoral Erectile Insuf®Ciency
    International Journal of Impotence Research (1997) 9, 27±37 ß 1997 Stockton Press All rights reserved 0955-9930/97 $12.00 Vasculogenic female sexual dysfunction: The hemodynamic basis for vaginal engorgement insuf®ciency and clitoral erectile insuf®ciency K Park, I Goldstein, C Andry, MB Siroky, RJ Krane and KM Azadzoi Department of Urology, Boston University School of Medicine and Boston Veteran's Administration Hospital, Boston, MA, USA Objective: Organic female sexual dysfunction may be related in part to vasculogenic impairment of the hypogastric-vaginal/clitoral arterial bed. The aim was to develop an animal model of vaginal engorgement insuf®ciency and clitoral erectile insuf®ciency. Methods: Pelvic nerve stimulated vaginal engorgement and clitoral erection were achieved in control (normal diet, n 8) and atherosclerotic (balloon injury of aorto-iliac arteries and 0.5% cholesterol diet, n 7) New Zealand White female rabbits. After 16 weeks, novel hemodynamic variables including vaginal wall and clitoral blood ¯ow, vaginal wall and clitoral intracavernosal pressure, vaginal length, vaginal luminal pressure, blood levels of cholesterol and triglycerides, aorto-iliac angiography and vaginal wall and clitoral erectile tissue histology were recorded in the two groups. Results: Concerning pelvic nerve stimulated vaginal hemodynamic changes, there was signi®cantly less increase in blood ¯ow (ml/min/100 gm tissue), wall pressure (mmHg) and length changes (mm) in atherosclerotic (9.3 Æ 3.7, 4.8 Æ 3.8, 67.3 Æ 8.3) compared to control (13.9 Æ 4.5, 5.5 Æ 2.6, 74.1 Æ 10.0) animals respectively. Histologic examination of clitoral erectile tissue demonstrated cavernosal artery atherosclerotic changes and diffuse vaginal and clitoral ®brosis.
    [Show full text]
  • Module 4: Erectile Dysfunction
    MODULE 4: ERECTILE DYSFUNCTION KEYWORDS: Erectile dysfunction, phosphodiesterase inhibitors, sexual dysfunction LEARNING OBJECTIVES At the end of this clerkship, the medical student will be able to: 1. Draw, identify and name the major anatomic regions of the penis involved with erections 2. Describe the physiology of the normal penile erection 3. List and briefly describe the major causes of erectile dysfunction (ED) 4. List the important components of the history when interviewing a patient with ED 5. Outline the important components of the physical exam of a patient with ED 6. List the treatment options for erectile dysfunction and describe the mechanisms by which they work 7. Describe the contra-indications and side-effects of phosphodiesterase inhibition for ED 8. Describe when a patient with ED should be referred to a urologist DEFINITION Erectile dysfunction is defined as the inability to achieve and maintain an erection sufficient for satisfactory sexual intercourse. It is estimated to affect 20 to 30 million men in the US. ED may result from impairment of one or most commonly, a combination of factors: psychological, neurologic, hormonal, arterial, and venous. More recently it has become clear that, in many cases, ED may be a “silent marker” for the later development of endothelial dysfunction and eventually, cardiovascular disease. THE PENILE ERECTION Penile erection is a neurovascular event subject to psychological and hormonal modulation. Upon sexual stimulation, nerve impulses release neurotransmitters from the cavernous nerve terminals and relaxing factors from the endothelial cells in the penis. Resultant smooth muscle relaxation in the arteries and arterioles supplying the erectile tissue results in a several-fold increase in blood flow.
    [Show full text]
  • Establishment of the Autonomic Neuroanatomy to the Vulval Erectile Tissues
    ESTABLISHMENT OF THE AUTONOMIC NEUROANATOMY TO THE VULVAL ERECTILE TISSUES by SHONA MARIE LOUISE PENHALE B.Sc, The University of British Columbia, 2000 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQU1RMENTS FOR THE DEGREE OF MASTERS OF SCIENCE in FACULTY OF GRADUATE STUDIES (DEPARTMENT OF ANATOMY) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA September 2003 © Shona Marie Louise Penhale UBC Rare Books and Special Collections - Thesis Authorisation Form Page 1 of 1 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. The University of British Columbia Vancouver, Canada http://www.library.ubc.ca/spcoll/thesauth.html 07/10/2003 ABSTRACT Erectile tissues are the vascular structures within the vulva that fill with blood and are an integral component of the woman's sexual response. Despite the importance of these structures to her sexual function, the detailed neuroanatomical pathways of the autonomic nerves underlying this mechanism of vascular congestion, have not been elucidated. Therefore, this research had been designed to identify the missing components to answer the question: "What is the pathway of the nerves running from the female pelvic plexus to the external genitalia?".
    [Show full text]
  • 68 External Genitalia-Male
    External Genitalia-Male Penis The penile urethra serves as a common channel for conducting urine and seminal fluid to the exterior. It is contained within a cylinder of erectile tissue, the corpus cavernosum urethrae (corpus spongiosum) that lies ventral to a pair of similar erectile bodies called the corpora cavernosa penis. Together the three structures make up the bulk of the penis, the copulatory organ of the male. The corpora cavernosa penis begins as separate bodies along the rami of the pubis on either side and joins at the pubic angle to form the shaft of the penis. They are united by a common connective tissue septum called the pectiniform septum, and each corpus is surrounded by a thick, primarily collagenous sheath, and the tunica albuginea. Trabeculae of collagenous and elastic fibers with numerous smooth muscle cells extend into the corpora from the tunica albuginea and divide the central regions of the corpora cavernosa into numerous cavernous spaces, those near the center being the larger. These spaces are endothelial-lined vascular spaces and are continuous with the arteries that supply them and with draining veins. The cavernous tissue of each corpus cavernosum penis communicates with the other through numerous slitlike openings in the pectiniform septum. The ventrally placed corpus cavernosum urethrae (corpus spongiosum) ends in an enlargement, the glans penis, which forms a cap over the ends of the corpora cavernosa penis. Structurally, corpus spongiosum is similar to the corpora cavernosa penis, but the tunica albuginea is thinner and contains more elastic fibers and smooth muscle cells, and the trabeculae are thinner and contain more elastic tissue.
    [Show full text]
  • The Role of Oxygen Tension in Penile Erection and Its Relationship to Erectile Dysfunction
    Articles TheScientificWorldJOURNAL (2004) 4 (S1), 279–290 ISSN 1537-744X; DOI 10.1100/tsw.2004.77 The Role of Oxygen Tension in Penile Erection and Its Relationship to Erectile Dysfunction Jong-Kwan Park, M.D., Ph.D.1, Robert B. Moreland, Ph.D.2, and Ajay Nehra, M.D.1 1Department of Urology; Mayo Clinic and Foundation, and Mayo Medical School, Rochester, Minnesota 55905; 2Departments of Urology and Physiology, Boston University School of Medicine, Boston, Massachusetts 02118 E-mails: [email protected] Previously published in the Digital Urology Journal The corpus cavernosum of the penis is one of the few vascular beds in which there is a change in oxygen tension with function (blood PO2 25-40mm Hg in the flaccid state, and 90-100mm Hg in the erect state). This change in oxygen tension exposes the components of the corpus cavernosum to a variety of cytokines, humoral, vasoactive, and growth factors which may affect the structure and function of the endothelial cells, smooth muscle cells, neurons and extracellular matrix. Among these cell types, endothelial cells are the first line of defense to blood-borne stress and can affect the underlying smooth muscle via paracrine mechanisms. Impotence is defined as the inability to obtain or sustain an erection sufficient for vaginal penetration and can result from a variety of pathological conditions, vascular disease, endocrine disease, neurological disease, and psychogenic disorders. The penis is a vascular organ and as such is susceptible to the effects of vascular diseases. This review will discuss the basic etiology of erection and vasculogenic erectile dysfunction and explore the role oxygen tension in regulating various cellular and humoral factors as well as trabecular structure and function.
    [Show full text]
  • Erectile Dysfunction (ED) in Men Is Neural System, and Experiencing Ejaculation Relies on Straight
    Dear Dr. Myrtle, clitoris (aka corpus cavernosa), and small blood When a man wants to use his penis for sexual as it has all of your life, and can make relationship What is ED? vessel function. Having an orgasm further tests the penetration, he needs this hardness to hold his penis problems difficult to solve. Erectile Dysfunction (ED) in men is neural system, and experiencing ejaculation relies on straight. Penetration can occur with softer erections, To find a professional who is particularly defined as an inability to achieve and maintain a penile yet another nerve system. The whole sexual system but the man needs to be careful not to bend the knowledgeable about sexual issues, visit the web erection sufficient for penetration. There is a broad isn’t complicated, but does require many parts to penis, since the elastic/fibrous clitoris can be broken site of the American Association of Sex Educators, range of erection troubles including: work together for sexual arousal to fully develop. when bent at an angle. Counselors and Therapists (www.aasect.org.) On • the inability to become hard at all, There are two ways to consciously initiate penile Physical Causes of Erectile Dysfunction their web page you will find public information on • becoming hard only briefly, erections: Today we know that physical causes (heart how to find a sex counselor or therapist in your area. • becoming only half-hard, and 1. Physically massage the penis, causing blood to flow disease, diabetes) of ED are more common It might be helpful to see a counselor alone, with • only occasionally becoming hard.
    [Show full text]
  • Cavernous Erectile System in Women and the Hypereroticism Area (H Area)
    Journal of Clinical Sexology - Vol. 3; No.3: July- September 2020 121 CAVERNOUS ERECTILE SYSTEM IN WOMEN AND THE HYPEREROTICISM AREA (H AREA) 1*Vasile NIȚESCU 1.*Medical Centre for Obstetrics-Gynaecology and Sexology The erectile organs of the vulva, through their structure and functionality, participate directly in determining the state of arousal and erection, necessary for sexual interc urse. The command to trigger an erection is given by the brain and is transmitted through the medullary pathways and/or the sacral spinal cord S2-S4, through the reflex arch. The direct connection between the cavernous erectile organs containing a venous ple- xus (vestibular bulbs) with the erectile tissue of the clitoris, the suburethral tissue, respec- tively the cavernous venous plexus of the urethra which constitutes the Vaginal Area of Hypereroticism (”H”), stimulates the receptors of any of the above structures in order to increase the local congestion and the vulvo-vaginal erectile sensitivity, thus activating the desire to mate (the ”libido”). It has to be mentioned that the erectile tissue covered by albuginea has a special func- tionality compared to the tissue with a simple local hyperemia (Niţescu). Parasympathetic impulses dilate the arteries of erectile tissue due to acetylcholine, to nitric oxide and to VIP (Vasoactive Intestinal Polypeptide) released at the nerve endings, local hyperemia highlighting the vulvo-vaginal erectile tissue. The connections between the corpora cavernosa of the clitoris and the corpora caver- nosa of the urethra are also explained by the drainage of venous blood, that is mainly and directly to the circumflex veins, which is another proof of the direct link between the clitoris and H area, all considered by women as being the most important vulvo-vaginal erogenous zones.
    [Show full text]