Faaletino o le Penile Erection ma le Pathophysiology o le Erectile Dysfunction (2006)

Urol Clin North Am. Tusiga a le tusitala; avanoa ile PMC 2006 Ianuari 25.
Faʻasalalauina i faʻamaufaʻailoga mulimuli:
PMCID: PMC1351051
NIHMSID: NIHMS6980
Robert C. Dean, MDa ma Tom F. Lue, MDb
Tusi tusitala ► Faamatalaga o le Puletaofia ma Laisene ►
O le lomiga mulimuli a le tagata faʻasalalau lomiga o lenei tusiga o loʻo avanoa i Urol Clin North Am
Vaai i isi tala i le PMC faʻailoa le lomiga lolomi.

The molecular and clinical understanding of erectile function continues to gain ground at a particularly fast rate. Advances in gene discovery have aided greatly in working knowledge of smooth muscle relaxation/contraction pathways. Intensive research has yielded many advances. The understanding of the nitric oxide pathway has aided not only in the molecular understanding of the tumescence but also aided greatly in the therapy of erectile dysfunction. As a man ages or undergoes surgery, preventative therapies to preserve erectile dysfunction have begun. All clinical interventions derived their beginning in a full anatomical, molecular, and dynamic knowledge base of erectile function and dysfunction. In this chapter the components of erectile function will be explained.

Alu i le:

Hemodynamics ma Mechanism of Erection and Detumscence

Corpora Cavernosa

O le penile erectile tissue, aemaise le cavernous smooth musculature ma maso lamolemole o le arteriolar ma arterial walls, e faia se sao taua i le erectile process. I le tulaga pa'epa'e, o maso lamolemole nei o lo'o fa'ama'i lelei, e fa'ataga ai na'o sina vaega itiiti o le tafega o alatoto mo mea'ai. Ole vaega ole toto ole okesene (PO2) e tusa ma le 35mmHg. 1 O lo'o i ai i se tulaga feololo le pa'u o le penis e vaivai, e pei ona molimauina i le fa'aitiitia atili i le tau malulu ma pe a uma ona tu'iina le phenylephrine.

O fa'aoso fa'afeusuaiga e fa'aoso ai le fa'asa'olotoina o neurotransmitters mai fa'ai'uga neura ana. E mafua ai le malolo o nei maso lamolemole ma mea nei:

  1. Fa'alolotoina o alatoto ma alatoto e ala i le faateleina o le tafe toto i vaega uma o le diastolic ma le systolic.
  2. Trapping of the incoming blood by the expanding sinusoids
  3. Fa'asalaina o plexuses venular subtunical i le va o le tunica albuginea ma le sinusoids peripheral, fa'aitiitia le tafe mai o le venous.
  4. Stretching of the tunica to its capacity, which occludes the emissary veins between the inner circular and the outer longitudinal layers and further decreases the venous outflow to a minimum
  5. Faʻateleina le PO2 (e tusa ma le 90 mmHg) ma le mamafa o le intracavernous (tusa ma le 100 mm Hg), lea e siitia ai le penis mai le tulaga faʻalagolago i le tulaga faʻavae (le vaega o le faʻavae atoa)
  6. Fa'ateleina le fa'atupuina o le mamafa (e o'o i le selau millimita o le mercury) fa'atasi ai ma le fa'aitiitiga o maso ischiocavernosus (vaega fa'atutu-malo)

O le maualuga o le penis fa'atutu e fuafua i lona tele ma lona pipii i le puboischial rami (le crura) ma le pito i luma o le ponaivi pubic (le suspensory ma funiform ligaments). I tamaloloa e umi le mamafa o le penis poʻo se ligament suspensory matala, o le maualuga e masani lava e le sili atu i le 90 tikeri, e tusa lava pe maʻaʻa atoatoa.

E tolu vaega o le detumescence ua lipotia i se suʻesuʻega manu.2 The first entails a transient intracorporeal pressure increase, indicating the beginning of smooth muscle contraction against a closed venous system. The second phase shows a slow pressure decrease, suggesting a slow reopening of the venous channels with resumption of the basal level of arterial flow. The third phase shows a fast pressure decrease with fully restored venous outflow capacity.

Erection thus involves sinusoidal relaxation, arterial dilatation, and venous compression.3 O le taua o le faʻamalieina o maso lamolemole ua faʻaalia i suʻesuʻega a manu ma tagata.4, 5

Corpus Spongiosum ma Glans Penis

Ole hemodynamics ole corpus spongiosum ma glans penis e fai si ese mai i le corpora cavernosa. I le taimi o le faʻavaeina, e faʻateleina le tafega alatoto i se auala tutusa; ae ui i lea, o le mamafa i totonu o le corpus spongiosum ma glans e na'o le tasi vaetolu i le afa o lena i le corpora cavernosa ona o le ufiufi ufi (e manifinifi i luga o le corpus spongiosum ma toetoe a leai i luga o glans) e mautinoa ai le itiiti o le fa'aogaina o le vena. I le taimi o le fa'atulagaina atoa, o se vaega fa'amalosi o le loloto o le pito i tua ma veins circumflex i le va o Buck's fascia ma le corpora cavernosa fa'apupulaina e saofagā i le pa'u o le glanular, e ui o le spongiosum ma glans o lo'o galue e pei o se arteriovenous shunt tele i lenei vaega. I le vaega fa'amaua'ina, o maso o le ischiocavernosus ma le bulbocavernosus e fa'amalosi malosi ai le spongiosum ma veins penile, lea e mafua ai le fa'atuputeleina atili ma le fa'ateleina o le mamafa i glans ma spongiosum.

Alu i le:

Neuroanatomy ma le Neurophysiology o Penile Erection

Peripheral Pathways

The innervation of the penis is both autonomic (sympathetic and parasympathetic) and somatic (sensory and motor). From the neurons in the spinal cord and peripheral ganglia, the sympathetic and parasympathetic nerves merge to form the cavernous nerves, which enter the corpora cavernosa and corpus spongiosum to affect the neurovascular events during erection and detumescence. The somatic nerves are primarily responsible for sensation and the contraction of the bulbocavernosus and ischiocavernosus muscles.

Autonomic Pathways

O le ala alofa e afua mai i le 11th tootoo i le 2nd lumbar spinal segments and passes through the white rami to the sympathetic chain ganglia. Some fibers then travel through the lumbar splanchnic nerves to the inferior mesenteric and superior hypogastric plexuses, from which fibers travel in the hypogastric nerves to the pelvic plexus. In humans, the T10 to T12 segments are most often the origin of the sympathetic fibers, and the chain ganglia cells projecting to the penis are located in the sacral and caudal ganglia.6

O le ala parasympathetic e tupu mai i neu i totonu o koluma sela o le lua, tolu, ma le fa sacral cord cord sections. O filo preganglionic e pasi atu i neura pelvic i le plexus pelvic, lea e faʻapipiʻi ai neura alofa mai le pito i luga ole hypogastric plexus. O neura cavernous o lala ia o le pelvic plexus e fa'aoso ai le penis. O isi lala o le pelvic plexus o loʻo faʻaulufaleina le saʻo, vevela, prostate, ma sphincters. O neura cavernous e faigofie ona faʻaleagaina i le taimi o le vavaeeseina o le saʻo, vevela, ma le prostate. O se malamalama manino o le ala o nei neura e taua i le puipuia o iatrogenic ED.7 O le faʻamaʻiina o le tino o le tagata na faʻaalia ai lala o le vaeluaga ma le pito i tua o neura cavernous (o le mea muamua e faʻatasi ma le urethra ma le mulimuli e tuia le urogenital diaphragm 4 i le 7 mm i le pito i tua i le sphincter) ma le tele o fesoʻotaʻiga i le va o le cavernous ma neura dorsal.8

O le fa'aosoina o le pelvic plexus ma neura cavernous e fa'atupu ai le fa'atutu, ae o le fa'aosofiaina o le ogalaau fa'aalofa e mafua ai le pa'u. O loʻo faʻaalia manino ai o le sacral parasympathetic input e nafa ma le tumescence ma o le thoracolumbar sympathetic auala e nafa ma le detumescence. I faʻataʻitaʻiga ma pusi ma isumu, o le aveeseina o le taulaʻau i lalo ole L4 poʻo le L5 na lipotia mai na faʻaumatia ai le tali faʻanofo erectile ae o le tuʻuina ma se fafine i le vevela poʻo le faʻamalosia o le eletise o le medial preoptic eria na maua ai le faʻailoga.9, 10 Na lipotia mai foi e Paick ma Lee o le apomorphine-induced construction e tutusa ma le psychogenic erection i le isumu ma e mafai ona faʻaosofia e ala i le auala alofa thoracolumbar i le tulaga o manuʻa i le sacral parasympathetic centres.11 I totonu o le tagata, o le tele o tagata gasegase o loʻo i ai le manua o le sacral spinal cord o loʻo tumau pea le malosi o le erectile psychogenic e ui lava ua faʻaumatia le fausiaina o le reflexogenic. O nei fa'aoso fa'aoso fa'aoso e maua soo i tagata mama'i ma'i la'ititi motoneuron i lalo ole T12.12 Leai se faʻavae psychogenic e tupu i tagata mamaʻi ma faʻamaʻi i luga aʻe o le T9; o lo'o fa'apea ona fa'ailoa mai e fa'apea o lo'o iai i le maualuga T11 ma le T12.13 Na lipotia mai foi, i nei tagata gasegase e maua i le psychogenic erections, o le umi ma le fula o le penis e matauina ae e le lava le malosi.

It is, therefore, possible that cerebral impulses normally travel through sympathetic (inhibiting norepinephrine release), parasympathetic (releasing NO and acetylcholine), and somatic (releasing acetylcholine) pathways to produce a normal rigid erection. In patients with a sacral cord lesion, the cerebral impulses can still travel by means of the sympathetic pathway to inhibit norepinephrine release, and NO and acetylcholine can still be released through synapse with postganglionic parasympathetic and somatic neurons. Because the number of synapses between the thoracolumbar outflow and the postganglionic parasympathetic and somatic neurons is less than the sacral outflow, the resulting erection will not be as strong.

Somatic Pathways

The somatosensory pathway originates at the sensory receptors in the penile skin, glans, and urethra and within the corpus cavernosum. In the human glans penis are numerous afferent terminations: free nerve endings and corpuscular receptors with a ratio of 10:1. The free nerve endings are derived from thin myelinated Aδ ma alava C e le mieliina ma e le pei o isi vaega pa'u i totonu o le tino.14 O alava neura mai le talitaliga e fefiloi e fai ai fusi o le neura pito i tua o le penis, lea e sosoo ai ma isi neura e avea ma neura pudendal. O le mea mulimuli e ulu atu i totonu o le vaʻa e ala i aʻa S2-S4 e faʻamutaina i luga o neurons spinal ma interneurons i le ogatotonu o le lanu efuefu o le vaega lumbosacral.15 Activation of these sensory neurons sends messages of pain, temperature, and touch by means of spinothalamic and spinoreticular pathways to the thalamus and sensory cortex for sensory perception. The dorsal nerve of the penis used to be regarded as a purely somatic nerve; however, nerve bundles testing positive for nitric oxide synthase (NOS), which is autonomic in origin, have been demonstrated in the human by Burnett et al. and in the rat by Carrier and coworkers.16, 17 Giuliano ma paaga ua faʻaalia foi o le faʻaosofia o le filifili alofa i le tulaga L4-L5 e faʻaalia ai se faʻalavelave faʻafuaseʻi i luga o le nerve dorsal o le penis ma le faʻaosofia o le nerve dorsal e faʻaosoina ai se faʻalavelave faʻafefe i le lumbosacral sympathetic filifili o isumu.18 O nei suʻesuʻega o loʻo faʻaalia manino ai o le neura dorsal o se neura fefiloi ma vaega somatic ma autonomic e mafai ai ona faʻatonutonu uma galuega erectile ma ejaculatory.

Onuf’s nucleus in the second to fourth sacral spinal segments is the center of somatomotor penile innervation. These nerves travel in the sacral nerves to the pudendal nerve to innervate the ischiocavernosus and bulbocavernosus muscles. Contraction of the ischiocavernosus muscles produces the rigid-erection phase. Rhythmic contraction of the bulbocavernosus muscle is necessary for ejaculation. In animal studies, direct innervation of the sacral spinal motoneurons by brain stem sympathetic centers (A5-catecholaminergic cell group and locus coeruleus) has been identified.19 O lenei adrenergic innervation o pudendal motoneurons e ono a'afia i fati fati o maso perineal a'o ejaculation. E le gata i lea, o le oxytocinergic ma le serotonergic innervation o le lumbosacral nuclei o loʻo pulea le faʻatutuina o penile ma maso perineal i le tamaʻi iole ua faʻaalia foi.20

Fa'alagolago i le malosi ma le natura o le fa'aosoina o le itutinosa, e tele fa'ata'ita'iga o le ivi e mafai ona fa'aosofia e ala i le fa'aosoina o le itutinosa. O le mea e sili ona lauiloa o le bulbocavernosus reflex, o le faʻavae lea o suʻesuʻega o le neurologic genital ma le suʻega electrophysiologic latency. E ui lava o le faʻaleagaina o maso bulbocavernosus ma ischiocavernosus e ono faʻaleagaina ai le fausiaina o penile, o le taua o le mauaina o se bulbocavernosus reflex i le aotelega o suʻesuʻega faʻaleagaina o feusuaiga e finau.

Supraspinal Pathways and Centers

O suʻesuʻega i manu ua faʻaalia ai le medial preoptic area (MPOA) ma le paraventricular nucleus (PVN) o le hypothalamus ma le hippocampus e avea ma nofoaga autu tuʻufaʻatasia taua mo le faʻafeusuaiga ma le faʻavaeina o le penile: o le electrostimulation o lenei vaega e faʻaosofia ai le faʻavaeina, ma faʻamaʻi i lenei nofoaga faʻatapulaʻa faʻatasi.21, 22 Marson et al. tui pseudo-rabies virus i totonu o le rat corpus cavernosum ma su'e neu fa'aigoaina mai le tele pelvic ganglia e o'o atu i neu i le va'ai, fai'ai ma le hypothalamus.22 Mallick ma tagata faigaluega na faʻaalia foi o le faʻaosofia o le neura pito i tua o le penis i le iole na aʻafia ai le fua o le fana e tusa ma le 80% o neu i le MPOA ae le o isi vaega o le hypothalamus.23 O auala eseese mai le MPOA e ulu atu i totonu o le ogatotonu o le muaʻi fusipaʻu ma le midbrain tegmental region (latalata i le substantia nigra). O faiga fa'aleaganu'u i nei itulagi, e pei o le ma'i o Parkinson po'o fa'alavelave fa'afuase'i o le cerebrovascular, e masani ona feso'ota'i ma fa'aletonu erectile. O le su'eina o le axonal i manuki, pusi ma isumu ua fa'aalia sa'o le va'aiga mai le hypothalamic nuclei i le lumbosacral autonomic fa'atoga. O neu i totonu o nei hypothalamic nuclei o loʻo i ai peptidergic neurotransmitters, e aofia ai le oxytocin ma le vasopressin, lea e ono aʻafia ai i le fausiaina o penile.21 Ole tele ole fai'ai ma le medullary centre o lo'o a'afia fo'i ile faiga fa'afeusuaiga. O le A5 catecholamine cell group ma locus ceruleus ua faʻaalia e tuʻuina atu ai le adrenergic innervation i le hypothalamus, thalamus, neocortex ma le taulaʻau. Fuafuaga mai le nucleus paragigantocellularis, lea e maua ai le serotonergic innervation inhibitory, ua faʻaalia foi i le hypothalamus, le limbic system, le neocortex ma le vaʻa.

Fa'agaioiina Neural Tutotonu i le taimi o Feusuaiga

Positron emission tomography (PET) ma le MRI galue (fMRI) ua faʻatagaina se malamalama sili atu i le faʻagaioiina o le faiʻai i le taimi o feusuaiga a tagata. Ole su'ega ole PET ma le fMRI e fa'atupula'ia ai le tafe toto ole cerebral po'o suiga ole gaioiga fa'aitulagi ole cerebral ile taimi fa'apitoa ole taimi. O le fa'aogaina o lenei tekonolosi, o le fa'afeusuaiga e fa'aosoina i tama'ita'i tama'ita'i fa'afeusuaiga mata'utia ma ata po'o vitio fa'afeusuaiga. O ata fa'ata'ita'i o fai'ai e pu'eina i taimi o fa'afeusuaiga e fa'atusaina i ata na pu'eina pe a fa'aalia ata e le fa'afeusuaiga i tamaloloa (malolo, fa'amaumauga, po'o ata vitiō malie). E mafai ona fa'aalia nofoaga autu e fa'agaoioia ai fai'ai fa'apea fo'i vaega e fa'ate'aina. E ui lava o le faigofie o nei suʻesuʻega e matagofie, e tele mea e aʻafia ai i le faʻafeusuaiga faʻafeusuaiga aemaise le faʻaosofia e mafua mai i faʻamatalaga vaaia. O tusitala o nei suʻesuʻega ua tuʻuina atu le tele o tulaga talafeagai i se taumafaiga e faʻavasega auala ma tagata auai; ae ui i lea, o le lavelave o lagona o le tagata ma le tali atu i feusuaiga e matua faigata lava ona faatonutonuina.

I le 1999, Stoleru et al. su'esu'e ni tama'ita'i fa'afeusuaiga lima taumatau e to'avalu fa'atasi ma le PET a'o fa'aoso fa'aoso fa'afeusuaiga.24 Itulagi o le fa'agaoioia o fai'ai na fa'amaopoopoina ma le maualuga o le testosterone plasma ma le tu'u o le penile. O le fa'agaoioia taua i le va'aiga fa'aoso fa'afeusuaiga na va'aia i le pito i lalo o le tino, insula taumatau, taumatau pito i lalo pito i luma, ma le agavale cingulate cortex. Mai lenei su'esu'ega mata'ina na fa'ailoa mai ai se fa'ata'ita'iga fa'ata'ita'i mo le galue o le fai'ai i le taimi o fa'afeusuaiga. O le faʻataʻitaʻiga e taʻu mai ai e tolu vaega o le faʻaalia o feusuaiga e fesoʻotaʻi ma o latou neuroanatomical eria: 1) o se vaega faʻapitoa-mafaufau - suʻesuʻeina le faʻaalia o le vaʻaia e pei o feusuaiga e faia i totonu o le tino i lalo ifo o le tino, 2) o se mea faʻalagona / faʻaosofia - faʻagasologa lagona. faʻamatalaga faʻatasi ma setete faʻaosofia e faia i le insula taumatau, taumatau pito i lalo pito i luma ma le agavale cingulate cortex (paralimbic area), 3) o se vaega physiological - faʻamaopoopo le endocrine ma autonomic galuega i le itu tauagavale cingulate cortex.

O isi su'esu'ega na faia i le fa'aaogaina o fa'aoso fa'afeusuaiga ma le su'esu'eina o le PET. Bocher et al. faʻaalia le faʻateleina o le faʻagaoioia i le pito i lalo pito i lalo, pito pito i tua o le tino (taumatau e sili atu nai lo le agavale), taumatau pito i lalo pito i luma pito i luma, gyrus agavale post-central, lobules pito i lalo pito i lalo, lobules pito i luga agavale, pou pito i luma (Brodmann area. 10), tu'u muamua pito i luma, ma vaega ogatotonu.25 Na taʻua foi e Bocher le faʻagata i le medial frontal ma luma cingulate, e feteenai ma le lipoti a Stoleru. Ma le isi, o nofoaga autu o fesoʻotaʻiga vaʻaia na maitauina e faʻagaoioia, aemaise lava i tua o le tino ma le post-central gyrus. O le mea e malie ai, o le faʻaogaina o le midbrain o loʻo vaʻaia i lenei suʻesuʻega e fesoʻotaʻi ma le nofoaga o le dopaminergic neurons. O le faʻagaoioia o le ogatotonu o le ogatotonu e leʻi faʻaalia i isi suʻesuʻega. O lenei fa'agaoioiga e mafai ona feso'ota'i ma fa'atupu fa'a'umi'umi. O le fa'aosofiaga fa'afeusuaiga va'aia na fa'aaogaina i lenei su'esu'ega o se ata vitio fa'aauau e 30-minute. O isi suʻesuʻega e faʻaaogaina ai faʻamalositino faʻafeusuaiga puʻupuʻu (2-10 minute).

Park et al. su'esu'e 12 alii soifua maloloina na auai i le faaaogaina o le fMRI.26 Viewing sexual erotic film clips were alternated with non-erotic clips. Regional brain activation was generally seen in the inferior frontal lobe, cingulate gyrus, insular gyrus, corpus collosum, thalamus, caudate nucleus, globus pallidus and inferior temporal lobes. Some activation regions were similar to other studies, in particular the inferior frontal lobes, inferior temporal lobes and the insular gyrus.

I se suʻesuʻega faʻatulagaina lelei e faʻaaoga ai le fMRI ma faʻaaliga faʻaalia e faʻapipiʻi faʻatasi ma le turgidity penile, Arnow et al. fa'aalia se vaega taua o le fa'agaoioia i le itu taumatau subinsular/insula e aofia ai le claustrum. 27 Activation of this region is similarly seen in past studies using PET.24, 28 O lenei itulagi ua fesoʻotaʻi ma le faʻaogaina o lagona. O le faʻagaoioia o le insula i lenei suʻesuʻega e mafai ona faʻatusalia le somatosensory gaioiga ma le iloa o le faʻavaeina. O isi vaega ole fai'ai na fa'agaoioia ile va'aiga fa'afeusuaiga va'aia o: gyrus ogatotonu taumatau, gyrus faaletino taumatau, caudate agavale ma putamen, bilateral cingulate gyri, taumatau sensimotor ma pre-motor itulagi. E le gata i lea, o se gaioiga laʻititi na vaʻaia i le hypothalamus taumatau. O loʻo faʻamoemoeina le Dopamine i le hypothalamus ma o le faʻamaoniga o le dopamine e faʻafaigofie ai amioga faʻafeusuaiga tane e tele. Ua toe vaaia foi le faagaioiina o le gyrus faaletino ogatotonu taumatau. Atonu e feso'ota'i ma le fa'atinoina o ata.

In 2003, Mouras et al. studied 8 men using fMRI; however, video clips were not used.29 Instead still photographs (neutral and sexually arousing) were shown quickly to participants. Using shorter visual sexual stimuli, they believed early neural responses would be generated instead of neural responses to the perception of penile tumescence. Again, activation of the middle and inferior occipital gyri was demonstrated, most likely linked to the visual stimuli not necessarily the sexual component. In addition to multiple brain centers that showed activation with visual sexual stimuli (bilateral parietal lobules, left inferior parietal lobule, right postcentral gyrus, right parietoccipital sulcus, left superior occipital gyrus, bilateral precentral gyrus), the cerebellum demonstrated activation in 3 subjects and deactivation in 4 subjects. Multiple other reports have demonstrated activation of the cerebellum in response to erotic films and viewing pictures of love partners. Therefore, it appears that visual sexual stimuli create activation in regions within the cerebellum.

Faatasi ai ma le alualu i luma ma le fMRI, o faʻatusatusaga auiliili o le faʻagaioiina o faiʻai i le tali atu i faʻamaʻi faʻafeusuaiga vaʻaia ua faia i luga o vaega eseese. Stoleru et al. su'esu'e mataupu tau tama soifua maloloina pe a fa'atusatusa i tamaloloa e le atoatoa le tu'inanau o tu'inanau (HSDD).30 O le agavale gyrus rectus, o se vaega o le medial orbitofrontal cortex o loʻo faʻaauau pea ona faʻagaoioia i tamaʻitaʻi ma le HSDD, lea e faʻatusatusa i lona faʻaleagaina i alii soifua maloloina e tali atu i faʻamaʻi faʻafeusuaiga vaaia. O lenei itulagi e talitonuina e fa'atalanoaina le pulea fa'alavelave o amioga fa'aosofia. Fa'aauau le fa'agaoioia o lenei itulagi e mafai ona fesoasoani e fa'amatala le pathophysiology o le HSDD. Montorsi et al. faʻatusatusa i tamaloloa e maua i le psychogenic erectile dysfunction (ED) ma faʻatonuga malosi pe a maeʻa le faʻaogaina o le apomorphine.31 I tamaloloa e iai le psychogenic ED ua faʻalauteleina le faʻagaoioia o le gyrus cingulated, luma o le mesial ma le pito i luma o le basal cortex na vaʻaia i le taimi o faʻamaʻi faʻafeusuaiga. O lenei faʻalauteleina o le faʻagaoioia e mafai ona fautua mai ai se faʻavae faʻavae mo le psychogenic ED. Faatasi ai ma le faʻaaogaina o le apomorphine, o le ata o le fMRI i tagata maʻi ED psychogenic e tutusa ma le malosi o le pulea. O le apomorphine na mafua ai le faʻamalosia atili o le foci i le psychogenic ED maʻi (vaʻaia i le nucleus accumbens, hypothalamus, mesencephalon). E le gata i lea, o le itu taumatau sa'o na sili atu ona fa'agaoioia nai lo le agavale ina ua mae'a le fa'atonuga o le apomorphine. O le fa'agaoioia o le itu taumatau agavale agavale ose su'esu'ega masani lea i totonu o su'esu'ega fa'aoso fa'afeusuaiga.

O le suʻesuʻeina o le faiʻai ma le PET ma le fMRI ua avea ma meafaigaluega mamana i le suʻesuʻeina o le faʻagaioiga tutotonu o le faʻafeusuaiga. Tele vaega fai'ai o le fa'agaoioia ua fa'aalia i nei lipoti. O nisi nofoaga autu o faiʻai masani o le faʻagaoioia ua mafai nei ona faʻamatalaina e ala i nei lipoti (Laulau 1). Psychogenic ED, ejaculation vave, faʻafeusuaiga faʻafeusuaiga, faʻalavelave faʻaleagaina o ni nai tulaga e ono iai se suiga i le maualuga o le faiʻai ma atonu o le taimi nei e mafai ona suʻesuʻeina. A'o amata ona tatou malamalama i le galue o le fai'ai i totonu o le tali masani o feusuaiga ma le faʻafefe, e mafai ona faʻamalamalamaina le mafuaʻaga o tulaga faʻaleagaina.

TABLE 1

Nofoaga fa'ato'aga fai'ai ma galuega fa'atatau

I le aotelega, o fausaga o loʻo i luga e nafa ma ituaiga e tolu o faʻavae: psychogenic, reflexogenic ma le po. O le fa'avaeina o le mafaufau e mafua mai i lagona fa'alogo po'o mafaufauga. O uunaiga mai le fai'ai e fa'aogaina ai nofoaga autu o le fa'atūina (T11-L2 ma S2-S4) e faʻagaoioia ai le faʻagasologa o le erectile. Reflexogenic faʻavae e gaosia e ala i faʻamalosi faʻamalosi i totoga itutino. E oʻo atu faʻamalosi i nofoaga autu o le faʻavaeina o le ivi; o nisi e mulimuli atu i le vaega alu a'e, e i'u ai i lagona fa'alogo, a'o isi e fa'agaoioia le nuclei tuto'atasi e lafo ai fe'au e ala atu i neura fa'ato'a i le penis e fa'aoso ai le fa'atupuina. O lenei ituaiga faʻavae e faʻasaoina i tagata mamaʻi e manuʻa i luga o le vaʻa. O le fausiaina o le po e tele lava ina tupu i le moe vave-mata-movement (REM). O su'esu'ega a le PET o tagata i le moe REM o lo'o fa'aalia ai le fa'ateleina o le gaioiga i le pontine area, le amygdalas ma le cingulate gyrus i luma ae fa'aitiitia le gaioiga i le pito i luma ma le parietal cortex. O le masini e mafua ai le moe REM o loʻo i totonu o le pontine reticular formation. I le taimi o le moe REM, o le cholinergic neurons i le lateral pontine tegmentum e faʻagaoioia ao le adrenergic neurons i le locus ceruleus ma le serontonergic neurons i le midbrain raphe e filemu. O lenei fa'agaoioiga fa'aeseese e mafai ona nafa ma fa'atonuga i le po i le taimi o le moe REM.

Alu i le:

Mechanism Molecular of Muscle Smooth Conditions and Relaxation

O musele lamolemole ma le malolo e fa'atonutonu e le cytosolic (sarcoplasmic) free Ca2+. Norepinephrine from nerve endings and endothelins and prostaglandin F2α from endothelium activate receptors on smooth muscle cells to increase inositol triphosphate and diacylglycerol resulting in release of calcium from intracellular stores such as sarcoplasmic reticulum and/or opening of calcium channels on the smooth muscle cell membrane leading to an influx of calcium from extracellular space. This triggers a transient increase in cytosolic free Ca2+ from a resting level of 120 to 270 to 500 to 700 nM.32 I le maualuga maualuga, o le Ca2+ e fusifusia i le calmodulin ma suia ai le tulaga mulimuli e faʻaalia ai nofoaga o fegalegaleaiga ma myosin light-chain kinase. O le fa'agaioiga fa'atupuina e fa'atupuina ai le phosphorylation o filifili mama myosin ma fa'aoso ai le uila o alalaupapa myosin (ulu) i luga o filament actin ma fa'atupuina le malosi. E le gata i lea, o le phosphorylation o le filifili mama e faʻagaoioia ai foʻi le myosin ATPase, lea e faʻafefe ai le ATP e maua ai le malosi mo le faʻaogaina o maso (Ata 1).

Ata 1

Molecular mechanism of penile smooth muscle contraction. Norepinephrine from sympathetic nerve endings and endothelins and PGF2a from the endothelium activate receptors on smooth muscle cells to initiate the cascade of reactions that eventually result ...

O le taimi lava na maua ai le cytosolic Ca2+ toe fa'afo'i le maualuga o le basal, o le ala e fa'alogoina ai le calcium. O se tasi o ia faiga e ala i le faʻagaoioia o mea faʻafiafia faʻatasi ma G-proteins lea e mafai foi ona mafua ai le faʻaitiitia e ala i le faʻateleina o le maaleale o le calcium e aunoa ma se suiga i le cytosolic Ca.2+ O lenei ala e aofia ai le RhoA, o se polotini G monomeric e fa'agaoioia ai le Rho-kinase. Fa'agaoioia Rho-kinase phosphorylates ma fa'afefe ai le vaega fa'atonutonu o musele lamolemole myosin phosphatase e taofia ai le dephosphorylation o myofilaments ma fa'atumauina ai le leo fa'akonekarate (Ata 2).33

Ata 2

RhoA/Rho kinase pathway: the calcium sensitization pathway.

RhoA ma Rho-kinase ua faʻaalia e faʻaalia i musele lamolemole penile.34, 35 O le mea e malie ai, o le aofaʻi o le RhoA o loʻo faʻaalia i totonu o le maso lamolemole cavernosal e 17 sili atu le maualuga nai lo le maso lamolemole vascular.35 O se inhibitor filifilia o le Rhokinase ua faʻaalia e faʻaalia ai le faʻamalieina o le tino o le tagata i le vitro ma faʻaosoina le faʻatutuina o penile i faʻataʻitaʻiga manu.36 O isumu fa'ama'i fa'ama'i fa'ama'i fa'atasi ma le RhoA fa'aletonu e fa'aalia ai le maualuga o le fa'aogaina o le erectile pe a fa'atusatusa i manu fa'atonutonu.37 The emerging consensus is that the phasic contraction of penile smooth muscle is regulated by an increase in cytosolic Ca2+ ma o le tonic contraction e pulea e ala o le calcium sensitizing ala.38

I le faaopoopo atu i le totonugalemu o le myosin phosphorylation i le malepelepe maso maso, o isi masini e mafai ona faʻaogaina pe faʻalelei le tulaga o le konekarate. Mo se fa'ata'ita'iga, o le caldesmon e ono a'afia i le latch state lea e fa'amautu ai le malosi o le fa'aitiitiga i se tulaga maualalo o le myosin phosphorylation ma fa'atasi ai ma le fa'aalu maualalo o le malosi.

Relaxation of the muscle follows a decrease of free Ca2+ in the sarcoplasma. Calmodulin then dissociates from myosin light-chain kinase and inactivates it. Myosin is dephosphorylated by myosin light-chain phosphatase and detaches from the actin filament, and the muscle relaxes.32 O isi o lo'o fautua mai o le NO-cGMP inhibitory ala i le corpus cavernosum musele lamolemole e le na'o se suiga o le fa'aliliuina o fa'ailoga fa'ailo; o se masini e le iloagofie e mafai ona saofagā i le malolo e ala i le faʻaitiitia o le fua o le faʻaogaina o le alalaupapa faʻalava e ala i le phosphorylation.

cAMP ma le cGMP o avefeau lona lua o loʻo aʻafia i le faʻamalieina o maso lamolemole. Latou te faʻagaoioia le cAMP- ma le cGMP-faʻalagolago i protein kinases, lea e faʻafefe ai nisi o polotini ma alavai ion, e iʻu ai i le (1) tatalaina o alavai o le potassium ma le hyperpolarization; (2) fa'auluina o le calcium intracellular e le endoplasmic reticulum; ma le (3) fa'alavelaveina ala o le calcium e fa'alagolago i le voltage, poloka le alu atu o le calcium. O le taunuuga o le pa'ū o le calcium free cytosolic ma faʻamalieina maso lamolemole (Ata 3).

Ata 3

O le mole mole o le fa'amalieina o maso lamolemole penile. O avefeau lona lua i totonu o le sela o loʻo faʻatalanoaina le faʻamalieina o maso lamolemole, cAMP ma le cGMP, faʻagaoioia a latou kinase protein faʻapitoa, lea e faʻasalaina ai ni polotini e mafua ai le tatalaina o le potassium. ...
Alu i le:

Patophysiology o le Erectile Dysfunction

faʻavasegaga

Many classifications have been proposed for ED. Some are based on the cause (diabetic, iatrogenic, traumatic) and some on the neurovascular mechanism of the erectile process (failure to initiate [neurogenic], failure to fill [arterial], and failure to store [venous]. A classification recommended by the International Society of Impotence Research is shown in Laulau 2.39

TABLE 2

Fa'avasegaina o le fa'aletonu o le erectile tane

Tomaʻi

I le taimi muamua, o le psychogenic impotence na talitonuina o le ituaiga sili lea ona taatele, ma le 90% o tane le atoatoa na manatu e mafatia i lenei tulaga.40 O lenei talitonuga ua maua ai le avanoa e iloa ai o le tele o tamaloloa e iai le ED o loʻo i ai se tulaga fefiloi atonu o le tele o galuega poʻo le tele o le tino.

O amioga fa'afeusuaiga ma le fa'atūina o penile e pulea e le hypothalamus, le limbic system, ma le cerebral cortex. O le mea lea, o feʻau faʻamalosi poʻo faʻalavelave e mafai ona tuʻuina atu i nofoaga autu o le faʻavaeina o le tui e faʻafaigofie pe faʻalavelaveina le fausiaina. E lua auala e mafai ona faʻatulagaina e faʻamatalaina ai le faʻalavelaveina o le faʻavaeina o le psychogenic dysfunction: faʻasaina tuusaʻo o le ogatotonu o le faiʻai e ala i le faʻateleina o le faʻalavelave masani suprasacral ma le faʻafefe tele o le alofa poʻo le maualuga o le maualuga o le catecholamine peripheral, lea e mafai ona faʻateleina ai le muso lamolemole penile. leo e puipuia ai le malolo e tatau mo le fausiaina.41 O su'esu'ega a manu o lo'o fa'aalia ai o le fa'aosoina o neura fa'aalofa po'o le fa'aogaina o le epinephrine e mafua ai le pa'u o le penis ua tu.42, 43 I le falemaʻi, o le maualuga o le serum norepinephrine ua lipotia i tagata mamaʻi e maua i le psychogenic ED nai lo faʻatonuga masani poʻo tagata mamaʻi ma vasculogenic ED.44

O Bancroft ma Janssen na fa'apea o le tali atu i feusuaiga a tama e fa'alagolago i le paleni i le va o le fa'aosofia ma le fa'alavelave i totonu ole CNS.45 O lo'o latou fa'ata'ita'ia fesili fa'afeusuaiga ma fa'afeusuaiga fa'aoso fa'afeusuaiga e mafai ona fesoasoani e iloa ai pe o le a sili atu le manuia o le fa'ai'uga a le tagata ma'i ile psychotherapy po'o togafitiga fa'afoma'i.

Neurogenic

Ua faʻatatauina o le 10 i le 19% o le ED e mafua mai i le neurogenic.46, 47 Afai o se tasi e aofia ai mafuaʻaga iatrogenic ma fefiloi ED, o le faʻateleina o le neurogenic ED atonu e sili atu le maualuga. E ui o le i ai o se faʻafitauli o le neurogenic poʻo le neuropathy e le aofia ai isi mafuaʻaga, faʻamaonia o le ED o le neurogenic i le amataga e mafai ona luitauina. Talu ai ona o le fa'atūina o se mea e tupu i le neurovascular, so'o se fa'ama'i po'o fa'aletonu e a'afia ai le fai'ai, va'ai, neura cavernous ma pudendal e mafai ona fa'atupu le fa'aletonu.

O le MPOA, o le paraventricular nucleus, ma le hippocampus ua manatu o se nofoaga taua e tuʻufaʻatasia mo le faʻafeusuaiga ma le faʻavaeina o penile.48 O faiga fa'aleaganu'u i nei itulagi, e pei o le ma'i o Parkinson, stroke, encephalitis, po'o le epilepsy lobe tino, e masani ona feso'ota'i ma ED. Ole a'afiaga ole Parkinsonism e ono mafua ile le paleni ole auala ole dopaminergic.49 O isi manu'a i le fai'ai ua maitauina e feso'ota'i ma le ED o tuma, tu'uvalea, fa'ama'i Alzheimer, Shy-Drager syndrome, ma manu'a.

I tamaloloa o loʻo i ai se manuʻa o le vaʻa, o latou galuega erectile e faʻalagolago tele i le natura, nofoaga, ma le lautele o le faʻamaʻi. I le faaopoopo atu i le ED atonu foi na latou faaletonu le ejaculation ma le orgasm. Reflexogenic fausia e faʻasaoina i le 95% o tagata mamaʻi o loʻo i ai faʻamaʻi maeʻa pito i luga, ae naʻo le 25% oi latou o loʻo i ai faʻamaʻi uma pito i lalo e mafai ona ausia se faʻavae.50 E foliga mai o sacral parasympathetic neurons e taua tele i le faʻasaoina o le faʻavaeina o le reflexogenic. Ae ui i lea, o le auala thoracolumbar e mafai ona totogi mo le leiloa o le sacral lesion e ala i fesoʻotaʻiga synaptic.10 In these men, minimal tactile stimulation can trigger erection, albeit of short duration, requiring continuous stimulation to maintain erection. Other disorders at the spinal level (e.g., spina bifida, disc herniation, syringomyelia, tumor, transverse myelitis, and multiple sclerosis) may affect the afferent or the efferent neural pathway in a similar manner.

Ona o le sootaga vavalalata i le va o neura cavernous ma totoga pelvic, o le taotoga i luga o nei totoga o se mafuaaga masani o le le atoatoa. O le aʻafiaga o iatrogenic impotence mai faʻasologa eseese ua lipotia mai e faapea: prostatectomy radical, 43% i le 100%; prostatectomy perineal mo faʻamaʻi mama, 29%; fa'amama fa'ama'i, 15% i le 100%; ma sphincterotomy fafo i le 3- ma le 9-itula tulaga, 2% i le 49%.51-56

O le faʻaleleia atili o le malamalama i le neuroanatomy o le pelvic ma cavernous neura ua iʻu ai i le toe faʻaleleia o taotoga mo le kanesa o le saʻo, vevela, ma le prostate, ma maua ai se faʻaitiitia o aʻafiaga o le le atoatoa o le iatrogenic.53 Mo se faʻataʻitaʻiga, o le faʻaofiina o le nerve-sparing radical prostatectomy ua faʻaitiitia ai le aʻafiaga o le le atoatoa mai le toeitiiti 100% i le 30-50%.57, 58 Toe fa'aleleia o le erectile galuega pe a mae'a le taotoga o le pelvic e mafai ona ave i le 6 i le 24 masina. O togafitiga muamua ma le intracavernous alprostadil poʻo le oral sildenafil ua faʻaalia e faʻaleleia ai le toe faʻaleleia o galuega erectile.59, 60 E talitonuina o le fa'aogaina o vaila'au fa'apitoa e puipuia ai suiga o le tino e feso'ota'i ma se fa'asolo pe leai fo'i i le taimi e toe fa'aleleia ai neura.

I tulaga o le gau o le pelvic, ED e mafai ona mafua mai i le manua o le nerve cavernous poʻo le le atoatoa o le vascular poʻo mea uma e lua. I se su'esu'ega a manu i isumu matutua, le ava malosi, le lava o vaitamini, po'o le ma'i suka e ono a'afia ai a'a neura ma e ono i'u ai i le le lava o neurotransmitters. I le ma'i suka, o le fa'aleagaina o le neurogenic ma le endothelium-faalagolago malolo e mafua ai le le lava o le NO.4 Because there is no direct means to test the autonomic innervation of the penis, clinicians should be cautious in making the diagnosis of neurogenic ED. NADPH diaphorase staining of the NANC nerve fibers in penile biopsy specimens has been proposed as an indicator of neurogenic status.61 O lo'o tu'uina atu fo'i e Stief ma pa'aga se su'esu'ega e tasi e ono mafai ona fa'aogaina le gaioioiga eletise mo le su'esu'eina o galuega a neura.62 Further studies are needed before these tests can be used routinely in clinical practice.

Bemelmans ma paaga na faia somatosensory evoked gafatia ma sacral reflex latencies i tagata mamaʻi e leai se faʻamaʻi faʻamaʻi o le neurologic ma iloa ai o le 47% e le itiiti ifo ma le tasi le fuaina o le neurophysiologic e le masani ai ma o se faʻalavelave e masani ona maua i tagata matutua matutua.63 O le faʻaitiitia o le lagona o le penile i le faʻatupulaia o le matua na lipotia foi e Rowland ma tagata faigaluega.64 E taua tele le sao mai le itutinosa i le ausiaina ma le faatumauina o le fausia o le reflexogenic, ma o le a sili atu le taua o le sao pe a faasolosolo malie ona leiloa e tagata matutua le fausiaina o le psychogenic. O le mea lea, o suʻesuʻega faʻapitoa e tatau ona avea ma se vaega taua o le iloiloga mo ED i tagata mamaʻi uma e iai pe leai foi se faʻafitauli o le neurologic.

Endocrinologic

O le Hypogonadism o se suʻesuʻega e le masani ai i le faitau aofaʻi o tagata mamaʻi. Androgens e aʻafia ai le tuputupu aʻe ma le atinaʻeina o tama tane ma uiga faʻafeusuaiga lona lua; o latou aafiaga i le libido ma amioga feusuai ua mautu lelei. I se iloiloga o tala faʻasalalau mai le 1975 i le 1992, Mulligan ma Schmitt faʻauʻu: (1) testosterone faʻaleleia le fiafia i feusuaiga; (2) fa'ateleina e le testosterone le tele o faiga fa'afeusuaiga; ma (3) fa'atuputeleina e le testosterone le tele o fa'ata'otoga i le po ae e la'ititi pe leai fo'i se a'afiaga i fa'atupu fa'anatura po'o le va'aia.65 O se suʻesuʻega e faʻatatau i le po ma le maualuga o le testosterone i tamaloloa, na lipotia mai ai o le faʻailoga mo faʻanofo masani i le po e tusa ma le 200 ng/dl.66 Men with lower serum testosterone levels often have abnormal nocturnal erection parameters compared to men with normal levels of testosterone. However, exogenous testosterone therapy in impotent men with borderline low testosterone levels reportedly has little effect on potency.67

E tele tagata suʻesuʻe na suʻesuʻeina le faʻaogaina o le aafiaga o androgen. Ua lipotia mai e Beyer ma Gonzales-Mariscal o le testosterone ma le dihydrotestosterone e nafa ma le male pelvic thrusting ma le estradiol poʻo le testosterone mo le tuʻiina o le pelvic tamaʻitaʻi i le taimi o le faʻamalosi.68 I isumu, ua fa'ailoa mai le fa'a'ese'ese e fa'aitiitia ai le tafega o alatoto, fa'aoso le tafega, ma fa'aitiitia ai le tusa ma le afa o le tali erectile i le fa'aosoina o le neura cavernous.69, 70 Togafitiga faʻatasi ma le flutamide, estradiol, poʻo se gonadotropin-releasing hormone antagonist faʻaopoopo i le castration e atili faʻavaivaia ai le tali erectile. E ui ina faʻaitiitia le gaioiga NOS penile i nei manu, o mea o loʻo i totonu o le neuronal NOS (nNOS) ma le endothelial NOS (eNOS) e le faʻaititia tele i togafitiga. E fa'atupuina fo'i e le fa'a'a'amea le tali atu ole α-adrenergic ole musele lamolemole penile, fa'ateleina le apoptosis ile corpus cavernosum i isumu, ma fa'aitiitia ai maso lamolemole trabecular ile lapiti.71-73 I le falemaʻi, o le tele o tamaloloa i le umi o le androgen ablation therapy mo le kanesa prostate ua lipotia mai le leaga o le libido ma le ED.

So'o se fa'aletonu o le hypothalamic-pituitary axis e mafai ona mafua ai le hypogonadism. Hypogonadotropic hypogonadism e mafai ona fanau mai pe mafua mai i se tuma po'o se manu'a; hypergonadotropic hypogonadism e mafai ona tupu mai se tuma, manu'a po'o se taotoga i le su'esu'e, po'o le mumps orchitis.

Hyperprolactinemia, whether from a pituitary adenoma or drugs, results in both reproductive and sexual dysfunction. Symptoms may include loss of libido, ED, galactorrhea, gynecomastia, and infertility. Hyperprolactinemia is associated with low circulating levels of testosterone, which appear to be secondary to inhibition of gonadotropin-releasing hormone secretion by the elevated prolactin levels.74

ED also may be associated with both the hyperthyroid and the hypothyroid state. Hyperthyroidism is commonly associated with diminished libido, which may be caused by the increased circulating estrogen levels, and less often with ED. In hypothyroidism, low testosterone secretion and elevated prolactin levels contribute to ED.

Arteriogenic

Atherosclerotic or traumatic arterial occlusive disease of the hypogastric-cavernous-helicine arterial tree can decrease the perfusion pressure and arterial flow to the sinusoidal spaces, thus increasing the time to maximal erection and decreasing the rigidity of the erect penis. In the majority of patients with arteriogenic ED, the impaired penile perfusion is a component of the generalized atherosclerotic process. Michal and Ruzbarsky found that the incidence and age at onset of coronary disease and ED are parallel.75 Common risk factors associated with arterial insufficiency include hypertension, hyperlipidemia, cigarette smoking, diabetes mellitus, blunt perineal or pelvic trauma, and pelvic irradiation.76-78 Na lipotia mai e Shabsigh ma paaga o suʻesuʻega faʻaletonu penile vascular na faʻateleina ona o le numera o faʻalavelave faʻalavelave mo ED faʻateleina.79 On arteriography, bilateral diffuse disease of the internal pudendal, common penile, and cavernous arteries has been found in impotent patients with atherosclerosis. Focal stenosis of the common penile or cavernous artery is most often seen in young patients who have sustained blunt pelvic or perineal trauma.77 O le uila umi-mamao ose tulaga lamatia foi mo vasculogenic ma neurogenic ED.80, 81

I se tasi lipoti, o alii maʻi suka ma tagata matutua e maualuga le aʻafiaga o faʻamaʻi fibrotic o le cavernous artery, faʻatasi ai ma le faʻalauteleina o le vavalalata, faʻamalama, ma le faʻamaʻi o le luminal.75 O le nikotina e mafai ona afaina ai le erectile e le gata i le faʻaitiitia o le tafe toto i le penis ae faʻapea foʻi i le polokaina o le faʻamalieina o maso lamolemole tino ma puipuia ai le faʻalavelave masani.82, 83

O le faaletonu o le erectile ma le ma'i fatu fatu e tutusa uma tulaga lamatia e pei o le toto maualuga, ma'i suka, hypercholesterolemia ma le ulaula. 84, 85O manu'a i alatoto pudendal e sili atu ona taatele i tama vaivai nai lo le faitau aofa'i o tagata matutua tutusa.86 O le mea lea e mafai ai ona avea le faaletonu o le erectile ma se fa'aaliga o fa'ama'i fa'alatele po'o fa'ama'i.87

Mechanism of Arteriogenic ED

1. Suiga Fausia

In ED due to arterial insufficiency, there is a decrease in oxygen tension in corpus cavernosum blood compared to that measured in patients with psychogenic ED.88 Since PGE1 and PGE2 formation is oxygen-dependent, an increase in oxygen tension is associated with elevation of PGE2 and suppression of TGF-β1-induced collagen synthesis in rabbit and human corpus cavernosum.89, 90 I le isi itu, o le fa'aitiitia o le okesene e mafai ona fa'aitiitia ai musele lamolemole trabecular cavernous ma ta'ita'i atu ai i le tafega o le venous.91, 92

O se lumen vaiti po'o le fa'atuputeleina o le pa i le lumen ratio i totonu o alatoto e saofagā i le fa'ateleina o le tete'e o le toto toto i le toto maualuga.93 Na maua fo'i le fa'ateleina o le tete'e i totonu o le penile vasculature o isumu toto maualuga (SHR), ma o nei suiga na mafua mai i suiga fa'avae o le alatoto ma le erectile.94-96 O le faʻateleina o le faʻalauteleina o le matrix extracellular e aʻafia uma ai le interstitium ma neural structures o le penis.

2. Vasoconstriction

Enhanced basal and myogenic tone has been observed in arteries from hypertensive rats. Enhanced sympathetic nerve activity accompanies hypertension has also been reported in man and hypertensive animals.97, 98 O le faʻaleleia atili o le vasoconstriction o le penile vasculature i le SHR na faʻaosoina e le infusion o le phenylephrine na mafua ona o le hypertrophy o le puipui vascular ae le o le suiga o neurotansmitters agaalofa.94

3. Fa'aletonu le Vasodilatation e faalagolago ile Endothelium

In patients with essential hypertension, endothelium-dependent vasodilatation elicited by infusion of agonists such as acetylcholine, bradykinin, or flow, is diminished.99-101 O fa'amaoniga lata mai ua fa'ailoa mai ai o le fa'aletonu tele o le endothelial i le ta'amilosaga o le fatu e mafai ona va'ai ai fa'alavelave tetele.102, 103 O le faaletonu o le Endothelial e fuaina e pei o le acetylcholine-induced vasorelaxation ua iloagofie i alatoto laiti mai tagata mama'i e maua i le toto maualuga.104, 105 However, there is a lack of study of penile endothelial function in hypertensive men.

In the SHR, the relaxing effect of acetylcholine is blunted both in large and in small arteries, and endothelial dysfunction appears to develop with the appearance of hypertension.106 O le malologa e faalagolago i le Endothelium e fa'aosoina e le acetylcholine e fa'aletonu fo'i i fasi tino mai le SHR ma e toe fa'afo'isia nei fa'amālōlō pe a iai le indomethacin.107 O le fa'aleagaina o le fa'amalologa fa'alagolago i le endothelium e mafai ona fa'atatau i le angiotensin II thromboxane ma le superoxide i alatoto mai le SHR po'o le toto maualuga.108-112

Cavernsal (Venogenic)

Failure of adequate venous occlusion has been proposed as one of the most common causes of vasculogenic impotence.113 Veno-occlusive dysfunction may result from the following pathophysiologic processes:

  1. Le i ai po'o le atina'eina o alavai lapopo'a o lo'o tafe ai le corpora cavernosa.
  2. Degenerative changes (Peyronie’s disease, old age, and diabetes) or traumatic injury to the tunica albuginea (penile fracture) resulting in inadequate compression of the subtunical and emissary veins. In Peyronie’s disease, the inelastic tunica albuginea may prevent the emissary veins from closing.114 Iacono ma tagata faigaluega ua faʻaalia e faapea o le faʻaitiitia o filo faʻamalosi i totonu o le tunica albuginea ma le suiga o le microarchitecture e ono fesoasoani i le le atoatoa i nisi o tamaloloa.115, 116 Changes in the subtunical areolar layer may impair the veno-occlusive mechanism, as is occasionally seen in patients after surgery for Peyronie’s disease.117
  3. Structural alterations in the fibroelastic components of the trabeculae, cavernous smooth muscle, and endothelium may result in venous leak.
  4. Le lava le fa'amalieina o maso lamolemole trabecular, e mafua ai le le lava o le sinusoidal faʻalauteleina ma le le lava o le faʻamalosi o le subtunical venules, e mafai ona tupu i se tagata popole ma le tele o le leo o le adrenergic poʻo se tagata maʻi e le lava le faʻamalolo o le neurotransmitter. Ua faʻaalia o le suia o le α adrenoceptor poʻo le faʻaitiitia o le NO faʻamalolo e mafai ona faʻateleina ai le leo lamolemole maso ma faʻaleagaina ai le malolo i le tali atu i le faʻamalolo maso.118
  5. Maua venous shunt—o le i'uga o le faasa'oga faagaoi o le priapism—e ono mafua ai le fa'asolosolo pea o glans/cavernosum po'o le cavernosum/spongiosum shunting.

Fibroelastic Component

Loss of compliance of the penile sinusoids associated with increased deposition of collagen and decreased elastic fibers may be seen in diabetes, hypercholesterolemia, vascular disease, penile injury, or old age.119, 120 Sattar and coworkers reported a significant difference in the mean percentage of elastic fibers in the penis: 9% in normal men, 5.1% in patients with venous leakage, and 4.3% in patients with arterial disease.121 I se faʻataʻitaʻiga manu o vasculogenic ED, Nehra ma paʻaga na faʻaalia ai o le faʻalauteleina o le cavernosal e fesoʻotaʻi ma musika lamolemole ma e mafai ona faʻaaogaina e vaʻai ai tala faʻasolopito.92 Moreland and colleagues have shown that prostaglandin E1 taofiofia le faʻaogaina o le collagen e ala i le suia o le tuputupu aʻe-β1 i maso lamolemole cavernous o le tagata, o lona uiga o le tui intracavernous o le prostaglandin E1 atonu e aoga i le puipuia o le fibrosis intracavernous.89

Musumu Malu

Talu ai ona o le maso lamolemole tino e pulea le gaioiga vascular e oʻo atu i le faʻavaeina, o le suiga o le maso lamolemole ma le ultrastructure e mafai ona faʻamoemoe e aʻafia ai le tali erectile. I se suʻesuʻega o le penile a le tagata, Sattar ma paaga na faʻaalia se eseesega tele i le va o le pasene o le maso lamolemole cavernous i tane malosi masani, pisia i le antidesmin (38.5%) poʻo le antiactin (45.2%), ma i le vaega venous (antidesmin). , 27.4%; antiactin, 34.2%) poʻo le vaega arteriogenic (antidesmin, 23.7%, antiactin, 28.9%).121 O se su'esu'ega fa'aolaola in vitro ua fa'aalia ai le fa'aletonu o le neurogenic ma le endothelium e feso'ota'i ma le fa'amalieina o musele lamolemole penile i tama ma'i suka.4 I vasculogenic ma neurogenic ED, o le maso lamolemole ua faaleagaina e mafai ona avea ma mea autu, faʻateleina le mafuaʻaga autu.122 O Pickard ma tagata faigaluega ua faʻaalia foi le faʻaleagaina o le malolo faʻaosoina o neura ma le α-adrenergic-faʻamalosia le faʻaitiitia o maso cavernous faʻapea foʻi ma le faʻaitiitia o maso i totonu o tamaloloa e maua i le venous poʻo le fefiloi venous / artery le malosi.123

O alavai o le ion e matua'i a'afia lava i mea fa'aolaola o le gaioiina o maso, ma o le suia o ala o le ion e ono i ai se aafiaga loloto i le gaioiina o maso. Na lipotia mai e Fan ma paaga se suiga o le maxi-K+ channel in cells from impotent patients and suggested that impairment in the function or regulation of potassium channels might contribute to the decreased hyperpolarizing ability, altered calcium homeostasis, and impaired smooth muscle relaxation in impotence patients.124 I suʻesuʻega a manu, na faʻaalia ai e Junemann ma paaga le faʻaleagaina o maso lamolemole ma le leiloa o fesoʻotaʻiga cell-to-cell i lapiti na fafagaina se meaʻai maualuga-cholesterol mo le 3 masina.82 In a rabbit model of vasculogenic impotence, Azadzoi and associates demonstrated that veno-occlusive dysfunction could be induced by cavernosal ischemia.125

Gap Junction

O nei fesoʻotaʻiga fesoʻotaʻiga fesoʻotaʻiga e nafa ma le tuʻufaʻatasia ma le faʻamaopoopoina o tali erectile, e ui lava e leʻi faʻamalamalamaina a latou aafiaga pathophysiologic.126, 127 I fa'ama'i fa'ama'i tuga, e va'aia le leiloa po'o le fa'aitiitia o le fa'afeso'ota'i o le membrane ona o le i ai o alava collagen i le va o sela fe'avea'i.128 O nei su'esu'ega o lo'o fa'aalia ai o le le lelei po'o le leiloa o gap junctions e ono suia ai le gaioiina o maso lamolemole.

Faamama

E ala i le tuʻuina atu o vailaʻau vasoactive, o le endothelium o le corpus cavernosum e mafai ona suia le leo o le maso lamolemole lata ane ma afaina ai le atinaʻeina poʻo le faʻasaina o se faʻavae. LEAI, prostaglandin, ma le polypeptide endothelins ua faʻamaonia i totonu o le endothelial cell.5, 91 Activation of cholinergic receptors on the endothelial cell by acetylcholine or stretching of the endothelial cells as a result of increased blood flow may elicit underlying smooth muscle relaxation through the release of NO. Diabetes and hypercholesterolemia have been shown to alter the function of endothelium-mediated relaxation of the cavernous muscle and impair erection.129

In summary, considerable events can cause erectile dysfunction. In addition no one cause may be involved independently. A cascade of issues (including psychological as well as organic) can lead the to the impotent state. A continued understanding of the organic causes of erectile dysfunction will allow the physician to discover therapies for correction as well as provide reassurance to the patient.

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