Powerful clinical and scientific experience suggests a close link between erectile dysfunction and heart disease. Studies like the Health Professionals Follow-up Study have revealed the risk factors for erectile dysfunction to be very similar to those for heart disease. Hypertension, smoking, diabetes, high cholesterol, obesity, and physical inactivity all strongly predict sexual dysfunction in men, as they do heart disease.1
Crossref | Google ScholarSee all References A 1985 study found that ED accounted for 400,000 outpatient visits and 30,000 hospital admissions per year in the United States, with a direct total cost of $146 million.4x4Feldman, HA, Goldstein, I, Hatzichristou, DG, Krane, RJ, and McKinlay, JB. Impotence and its medical and psychosocial correlates: results of the Massachusetts Male Aging Study. J Urol. 1994; 151: 54–61
Not surprisingly, they found that diabetic patients rated kidney disease and blindness as the two most important complications of their condition. Diabetic men with ED ranked ED as the third most important complication of diabetes, followed on average in order by foot ulcers, high blood pressure, high cholesterol, migraine headaches, sleeping disorders, and mild indigestion. Diabetic men without ED found ED slightly less important, ranking it behind foot ulcers and high blood pressure, although all three were grouped fairly close together (mean ranks were 4.59, 4.23, and 4.52, respectively). Interestingly, in men both with and without ED, subjects were willing to pay more per month to avoid ED than all other conditions except blindness and kidney disease (mean values for diabetic patients with ED were £50.5, £88.0, and £66.1, respectively). In summary, erectile function is important to diabetic men, and when ED is present, it has a significant negative effect on quality of life.
The use of penile support device such as penile cast worn externally during intercourse has been tried to provide length and rigidity to the penile shaft (24). Each device can be customised to the patient’s penile size and provided an option for patients who are seeking non-pharmaceutical/non-invasive treatment, or have end-organ failure who may not be candidates for, or unable to afford, penile prosthesis implant.

In particular, patients are classified into three categories (low, intermediate, high) depending on their CV risk profile. Individuals with controlled hypertension belong to the low-risk group where sexual dysfunction can be safely managed with the approved medical therapies regardless of the number or class (with the exception of b-blockers and diuretics) of agents of the patient’s antihypertensive regime. Moreover, patients of this group can safely initiate or reinstitute sexual activity without any need for additional cardiovascular evaluation.
medicines called alpha-blockers such as Hytrin (terazosin
HCl), Flomax (tamsulosin HCl), Cardura (doxazosin
mesylate), Minipress (prazosin HCl), Uroxatral (alfuzosin HCl),
 Jalyn (dutasteride and tamsulosin HCl), or Rapaflo (silodosin).
Alpha-blockers are sometimes prescribed for prostate
problems or high blood pressure. In some patients, the use
of Sildenafil with alpha-blockers can lead to a drop in blood pressure or to fainting
Ginseng is the most common ingredient among top-selling supplements for men’s sexual health (36). The English word ginseng derives from the Chinese term renshen. Ren means “person” and shen means “plant root”. This plant has been named in this manner as its roots resemble the lower limbs of a human, Traditionally, ginseng has been used to restore and enhance the normal well-being of the body. The effects are due to ginseng’s reactions with the central nervous system, metabolism, immune function and cardiovascular system. The principal active compounds are triterpene saponins known as ginsenosides. Animal studies have suggested that specific ginsenosides may be responsible for ginseng-mediated effects on copulatory behavior (37). Ginsenoside induces smooth muscle relaxation by hyperpolarizing the smooth muscle membrane via activation of large-conductance KCa channels (38).
Abstract | Full Text | Full Text PDF | PubMed | Scopus (259) | Google ScholarSee all References Sildenafil should be used with caution in patients with liver dysfunction or renal impairment, as well as in patients taking any medications that inhibit the P-450 pathway such as cimetidine or erythromycin.3x3Zusman, RM, Morales, A, Glasser, DB, and Osterloh, IH. Overall cardiovascular profile of sildenafil citrate. Am J Cardiol. 1999; 83: 35C–44C
Penile erection is largely a vascular process, and the penile endothelium and smooth muscle tissue are very sensitive to functional and structural changes. Vasculogenic ED results from an impairment of endothelial dependent or independent smooth muscle relaxation (functional vascular ED, initial stages), occlusion of the cavernosal arteries by atherosclerosis (structural vascular ED, late stages), or a combination of these.3 Current data support a complex interplay between endothelial dysfunction, subclinical inflammation, and androgen deficiency (Figure 1). The relationship between ED and CAD at the clinical level is supported by this common pathophysiological basis. The ‘artery size’ hypothesis explains why patients with CAD frequently report ED before CAD detection.10 According to this hypothesis, for a given atherosclerotic burden, the smaller penile arteries suffer obstruction earlier than the larger coronary arteries (Figure 2). The same concept holds also true in the case of non-obstructing atherosclerosis: since the smaller penile artery have a greater endothelial surface and erection requires a large degree of vasodilation to occur when compared with arteries in other organs, the same degree of endothelial dysfunction will be symptomatic in these smaller vessels but subclinical in the larger ones (i.e. coronaries). In the same context, accelerated arterial ageing (as indicated by increased arterial stiffening that also affects large arteries of ED patients) may be a common background.11,12 Erectile dysfunction is associated with an incremental inflammatory and endothelial-pro-thrombotic activation.13 Interestingly, this activation is equal to that found in CAD patients with no ED, while when these two conditions are combined the burden is additive. Androgen deficiency may be also implicated in the common pathogenetic pathways of ED and CVD; however, this warrants further substantiation.2

People sometimes refer to ED as "impotence," although the two aren't really the same condition. ED is the physical inability to develop or maintain an erection that is rigid enough for sex. Impotence is a broader term. While one cause of it is ED, impotence may also involve a lack of sexual desire, an inability to ejaculate, or problems with orgasm.
Phosphodiesterase Inhibitors. The cornerstone of first-line therapy is the PDE-5 inhibitor. No other class of oral agents approaches the efficacy of PDE-5 inhibitors. Yohimbine, trazodone, phentolamine, L-arginine, and OTC herbal remedies have been used with very limited success. The superiority of yohimbine over placebo in the treatment of organic ED is a matter of dispute.9 A recent trazodone study failed to detect any difference between trazodone and placebo on sexual function.10 Oral phentolamine, although available in Mexico, has not been approved by the US FDA for the treatment of ED. Apomorphine, a central dopaminergic receptor drug, has recently been voluntarily withdrawn from FDA consideration for the treatment of ED. The efficacy of ginkgo biloba and Korean red ginseng has yet to be demonstrated by randomized, placebo-controlled trials.
Erectile dysfunction is an accurate predictor of heart attacks and strokes in the future. Psychogenic components play a role in erectile dysfunction, but the most common and primary cause in most men is organic vascular insufficiency, meaning not enough blood gets to the penis. Erectile dysfunction usually occurs one to five years before a male manifests overt signs of cardiovascular disease. The first sign may be death.
Currently, the preferred treatment for erectile dysfunction includes sildenafil (Viagra), vardenafil (Levitra) and tadalafil (Cialis). However, numerous experts have raised concerns about the use of these drugs in patients with chronic heart failure who also take nitrates (or other medications that relax and widen blood vessels). This drug combination has been shown to be dangerous, because it can increase the risk for a life-threatening drop in blood pressure.
Before taking any medication for erectile dysfunction, including over-the-counter supplements and herbal remedies, get your doctor's OK. Medications for erectile dysfunction do not work in all men and might be less effective in certain conditions, such as after prostate surgery or if you have diabetes. Some medications might also be dangerous if you:
The diagnosis of ED in a patient may affect its management in two ways.30 The first relates to the fact that the ED patient, irrespective of whether he has or has not established CVD, is ‘reclassified’ into a higher risk category for future CV events. Management in this case is altered in the sense that more aggressive treatment of risk factors, as well as a close follow-up, is warranted. Implementation of biomarkers in this setting is desirable.
These medications don’t work for everyone but they are easy to use and work for around 60% of people who try them. They work by making it easier to get an erection by reducing the effect of (inhibiting) the chemical PDE-5. This chemical is used in the body to make sure there isn’t too much blood in the penis during an erection, but if you have erectile dysfunction then this chemical ends up over-compensating.
A cold slice of watermelon can do more than just satisfy thirst and hunger during the warm summer months; it can help with bedroom satisfaction. Citrulline, the amino acid found in high concentrations of watermelon, is found to improve blood flow to the penis. A 2011 study revealed men who suffered from mild to moderate ED and took L-citrulline supplementation showed an improvement with their erectile function and were very satisfied. Natural watermelon juice, or “nature’s Viagra,” can also be easier on the stomach, since taking pills like Viagra can cause nausea and diarrhea.
Abstract | Full Text | Full Text PDF | PubMed | Scopus (24) | Google ScholarSee all References Withdrawal of sexual stimulation causes a return of sympathetic tone and degradation of cGMP, predominantly by phosphodiesterase type 5 (PDE-5) within the trabecular smooth muscle.11x11Nehra, A. Intracavernosal therapy: when oral agents fail. Curr Urol Rep. 2001; 2: 468–472

Joel Fuhrman, M.D. is a board-certified family physician, six-time New York Times bestselling author and internationally recognized expert on nutrition and natural healing, who specializes in preventing and reversing disease through nutritional methods. Dr. Fuhrman coined the term “Nutritarian” to describe his longevity-promoting, nutrient dense, plant-rich eating style.
Most importantly, herbal supplements are not well regulated in the United States.  Studies have shown that 40-50% of herbal supplements do not even contain the supposed main ingredient, and many contain substances that are not listed which may have dangerous side effects2.  Another study found that over two thirds of the products tested had substituted other plant species for the plants listed on the label, and a third of products also contained other fillers or contaminants3.  A study by the New York State Attorney General of herbal products sold at GNC, Target, Walgreens, and Walmart found that four out of every five products didn’t contain the ingredient they claimed!  Fourteen US states and territories have petitioned Congress to regulate the herbal supplements industry.
Abnormalities in the vascular, neural, endocrine, muscular, or psychiatric systems can result in ED.2,3 EDDM is due to multisystemic disease. Atrophy or apoptosis of cavernosal smooth muscle can occur due to loss of Bcl-2 expression in cavernosal smooth muscle and lead to ED. Abnormal amounts of advanced glycation end products is a common occurrence. These chemicals may have an effect on potassium channels that facilitate intracellular calcium release and subsequent cavernosal smooth muscle relaxation. Connective tissue synthesis is increased due to transforming growth factor-beta. The decrease in smooth muscle and the increase in collagen decreases the compliance of the erectile tissue. Neuropathic damage to both the somatic and autonomic nerves has been clearly defined in DM. Partial occlusion of the pelvic or intracavernosal arteries, hypogonadotropic hypogonadism, and depression associated with a chronic illness (DM) can all play a primary or secondary role in the development of EDDM. On a molecular level, studies have demonstrated decreased levels of endothelial and neuronal nitric acid synthase (NS) and decreased cavernosal artery and sinusoidal response to nitric oxide. Abnormalities in nitric oxide rapidly render the functional syncytium of the corpora cavernosa unable to synchronously relax. As the patient with diabetes ages, the concentration of constrictors, including endothelin, prostanoids, and possibly angiotensin, increases as the production of the relaxants, including nitric oxide, vasointestinal peptide, and prostacyclin, decreases.
Hey folks, It's great to have met you, I really do hope that you enjoyed this article and found it helpful and informative. I Suffered from ED for a few years before taking a short while to reverse it after going down the usual route of those little blue (and expensive) pills, (not an actual cure but a treatment to temporarily relieve the symptoms).Be sure to check out My Highly Recommended products and start taking positive steps in the right direction to cure your erectile dysfunction. And don't forget to grab your free copy of The Testosterone Report and The Morning Wood Report
The drugs you take to lower your blood pressure may earn you lower marks in the bedroom, by leading to a bout of erectile dysfunction (ED), or the inability to get or maintain an erection during sex. High blood pressure medications such as beta blockers and diuretics do their life-saving job by lessening blood flow to your vital organs—and that includes down under. Less blood flow means no erection. The good news for guys is that not all high blood pressure medication cause ED. Talk with your doctor about switching to the ones that don't.
If you take a diuretic, you should stay on it until high blood pressure is under control. If erection problems persist, or blood pressure goes back up, then your doctor might switch to a drug that's less likely to cause erectile dysfunction. Or, a combination of medications might work better to control high blood pressure and lower the risk of erectile dysfunction.
Penile erection is largely a vascular process, and the penile endothelium and smooth muscle tissue are very sensitive to functional and structural changes. Vasculogenic ED results from an impairment of endothelial dependent or independent smooth muscle relaxation (functional vascular ED, initial stages), occlusion of the cavernosal arteries by atherosclerosis (structural vascular ED, late stages), or a combination of these.3 Current data support a complex interplay between endothelial dysfunction, subclinical inflammation, and androgen deficiency (Figure 1). The relationship between ED and CAD at the clinical level is supported by this common pathophysiological basis. The ‘artery size’ hypothesis explains why patients with CAD frequently report ED before CAD detection.10 According to this hypothesis, for a given atherosclerotic burden, the smaller penile arteries suffer obstruction earlier than the larger coronary arteries (Figure 2). The same concept holds also true in the case of non-obstructing atherosclerosis: since the smaller penile artery have a greater endothelial surface and erection requires a large degree of vasodilation to occur when compared with arteries in other organs, the same degree of endothelial dysfunction will be symptomatic in these smaller vessels but subclinical in the larger ones (i.e. coronaries). In the same context, accelerated arterial ageing (as indicated by increased arterial stiffening that also affects large arteries of ED patients) may be a common background.11,12 Erectile dysfunction is associated with an incremental inflammatory and endothelial-pro-thrombotic activation.13 Interestingly, this activation is equal to that found in CAD patients with no ED, while when these two conditions are combined the burden is additive. Androgen deficiency may be also implicated in the common pathogenetic pathways of ED and CVD; however, this warrants further substantiation.2
If your doctor says it's OK, you may be able to stop taking blood pressure medications temporarily to see if your sex life improves. To make sure your blood pressure remains within a safe range, you may need frequent blood pressure readings while you're not taking the blood pressure lowering medication that may be causing your sexual difficulties. This can be done with a home blood pressure monitoring device for convenience.
With atherosclerosis, the blood vessels are not able to dilate properly, which is called endothelial dysfunction (see the Figure). Cholesterol builds up in the blood vessel walls and forms plaques, which make the vessels narrow and slow down blood flow. When a plaque becomes very advanced, it can completely stop blood from passing through, which is what happens in a heart attack. Atherosclerosis affects not only the blood vessels supplying the heart (coronary arteries), but also blood vessels throughout the entire body. Atherosclerosis causes angina (chest pain that is often exertional), heart attacks, strokes, claudication (pain in the legs with walking), and ED. Atherosclerosis affects different people in different places, but it often affects the penis first, then the heart and brain, and the legs last. Because the first stage of atherosclerosis, endothelial dysfunction, usually affects the penis first, ED can be a warning sign that a heart attack or a stroke may follow, often in the next 3 to 5 years. This warning sign can be a good thing if it alerts you and your doctor that you have atherosclerosis, because then you can take steps to treat the atherosclerosis and prevent a heart attack or stroke.
However, sildenafil should be used carefully with nitrates because their combination can result in severe hypotension and death.68 Both short- and long-acting nitrates are commonly prescribed to treat angina, but they have no prognostic benefit. In addition, there are numerous alternatives to treat angina, such as ranolazine and ivabradine, which do not interact with PDE5 inhibitors. As a result, patients with ED wishing to take PDE5 inhibitors can safely discontinue their nitrates and replace this treatment with the other anti-anginal agents.68
Diuretics: Also called water pills, this medication is a common treatment for reducing blood pressure. They work by getting rid of unnecessary water and salt in the urine. This essentially helps lower blood pressure and can make it easier for the heart to pump blood. Unfortunately, diuretics can reduce the blood flow to the penis, making erections difficult to achieve. Zinc levels have been known to diminish due to diuretic use, which may lead to a decreased production of overall testosterone.
Chlamydia and erectile dysfunction: What's the link? Some people who have chlamydia also experience erectile dysfunction (ED), which involves problems getting or maintaining an erection. Chlamydia can infect the prostate gland, leading to prostatitis, pain, and ED. In this article, learn more about the link between this common infection and ED, and treatments for both. Read now
Abstract | Full Text | Full Text PDF | PubMed | Scopus (66) | Google ScholarSee all References Overall, sexual intercourse does not lead to an extremely exaggerated heart rate or blood pressure level when performed in a familiar setting with one's usual partner.82x82Hellerstein, HK and Friedman, EH. Sexual activity and the postcoronary patient. Arch Intern Med. 1970; 125: 987–999
Actually the first simple step to managing your blood pressure is to start tracking it! Get an inexpensive blood pressure cuff at CVS or on Amazon. Download the free Hello Heart app (iOS, Android) from the iTunes Store and Google Play.  Start recording your daily blood pressure. Just the simple act of daily recording can have a very beneficial effect.
The connection between diabetes and ED is related to your circulation and nervous system. Poorly controlled blood sugar levels can damage small blood vessels and nerves. Damage to the nerves that control sexual stimulation and response can impede a man’s ability to achieve an erection firm enough to have sexual intercourse. Reduced blood flow from damaged blood vessels can also contribute to ED.
Crossref | PubMed | Scopus (539) | Google ScholarSee all References The MMAS found the total prevalence of minimal to severe ED to be 52% and estimated that more than 617,000 new cases were expected to occur annually in the United States.4x4Feldman, HA, Goldstein, I, Hatzichristou, DG, Krane, RJ, and McKinlay, JB. Impotence and its medical and psychosocial correlates: results of the Massachusetts Male Aging Study. J Urol. 1994; 151: 54–61
PubMed | Google ScholarSee all References A dose-related phenomenon with propranolol use was suggested by another study, which showed that patients receiving propranolol dosages exceeding 120 mg/d developed ED at a higher rate than patients who received lower dosages of the same medication.43x43Warren, SC and Warren, SG. Propranolol and sexual impotence [letter]. Ann Intern Med. 1977; 86: 112
The discovery in 1992 of the second messenger of cavernosal smooth muscle relaxation was the critical step that led to the era of nonhormonal oral drug therapy for ED. In 1998, the multicenter trial of sildenafil in the treatment of ED was published in the New England Journal of Medicine, and the era of the phosphodiesterase type 5 (PDE-5) inhibitor began.1 For 5 years, sildenafil was the primary therapy for men with EDDM. Recently, 2 new PDE-5 inhibitors, vardenafil and tadalafil, were introduced.
It's an all too common problem: Roughly half of men with diabetes—and up to 25 percent of men overall—experience erectile dysfunction (ED) at some point in their lives. And it's a complicated problem, too, with diverse physical origins and complex emotional ramifications. Yet diabetes-related ED needn't be a no-sex sentence for men. There are ways to avoid this disorder and to treat it at any age. While much of the research on ED is still in its infancy, here is what science has to say so far.

If your physician advises you that the risks of taking an erectile dysfunction medication are too high, he or she can advise you of other treatment options that can enable you to resume sexual activity without risks of complications. These might also include screening to try to determine if your erectile dysfunction has a physiological basis in need of medical intervention, can be corrected through lifestyle changes or if it may have psychological roots. After all, a heart attack or diagnosis of heart disease can lead to depression, which can also affect libido. Talk with your doctor to establish a safe, effective plan for resuming intimacy after your heart disease diagnosis.
Based on this testing, EDDM patients were treated with behavioral therapy, intracavernosal (papaverine, PGE-1, or Trimix) or intraurethral PGE-1, a vacuum constriction device (VCD), or implantation of a penile prosthesis. Novel surgical procedures, ligation of incompetent cavernosal veins or penile revascularization, were seldom efficacious with EDDM and were soon abandoned. Although these nonsurgical therapies were efficacious, they were not widely requested because of their invasive or mechanical nature.
Vascular disease: Vascular diseases are those that affect the blood vessels. These diseases include atherosclerosis (hardening of the arteries), hypertension (high blood pressure), and high cholesterol. These diseases, which account for 70% of physical-related causes of ED, restrict blood flow to the heart, the brain, and--in the case of ED--to the penis. Atherosclerosis alone accounts for 50%-60% of ED cases in men over age 60.
 Other treatment options such as penile self-injection therapy, external vacuum pumps and the medicated urethral system for erection are on rare occasions an effective long-term treatment. A very small percentage of men will continue with these treatments as evidenced by a very high drop out rate and a very low refill rate for these treatments. These procedures require extensive planning which interfere with sexual spontaneity and are really not a realistic long-term treatment for young patients with permanent ED. 
Crossref | PubMed | Scopus (24) | Google ScholarSee all References Almost every class of antihyper-tensive medication has been implicated in causing ED; however, most of these studies, published as case reports or patient surveys, have been relatively subjective and uncontrolled.4x4Feldman, HA, Goldstein, I, Hatzichristou, DG, Krane, RJ, and McKinlay, JB. Impotence and its medical and psychosocial correlates: results of the Massachusetts Male Aging Study. J Urol. 1994; 151: 54–61
Testosterone cypionate and testosterone enanthate injections are used for replacement therapy in patients with low testosterone. Other formulations, such as gels and patches, are recommended in older patients with chronic conditions.57 Serum prostate specific antigen should be measured before starting testosterone replacement, then 3–6 months after starting the treatment, followed by annual measurement.74

In DM patients with a documented androgen deficiency, testosterone replacement may correct or facilitate the treatment of ED.7 A transdermal testosterone gel or patch, or intramuscular testosterone cypionate are the alternatives. Oral testosterone is contraindicated in the United States due to hepatotoxicity, but a new product has been developed that allows for buccal absorption of testosterone. Thyroid supplements rarely alleviate EDDM.
Undoubtedly, heart disease is and will continue to be one of the major health problems of modern society. Approximately one death every forty seconds occurs due to cardiovascular (CV) disease in the United States alone and arterial hypertension is one of the greatest culprits for it[1]. Considering the fact that around 25% of the global population suffer from arterial hypertension, predicted to reach 1.5 billion people in the foreseeable future, it is easily deducted that a respectful part of the general population is under major and constant CV risk[2,3].
PubMed | Google ScholarSee all References This prolonged excretion half-life produces enhanced erections up to 36 hours after oral dosing, thereby potentially allowing for more spontaneous engagement of intercourse. The efficacy of tadalafil in the treatment of ED has been proved in randomized double-blind, placebo-controlled trials.78x78Porst, H, Padma-Nathan, H, Giuliano, F, Anglin, G, Varanese, L, and Rosen, R. Efficacy of tadalafil for the treatment of erectile dysfunction at 24 and 36 hours after dosing: a randomized controlled trial. Urology. 2003; 62: 121–125
David F. Penson, MD, MPH, is an associate professor of urology and preventive medicine in the Keck School of Medicine at the University of Southern California, in Los Angeles. Hunter Wessells, MD, is an associate professor of urology at the University of Washington School of Medicine and chief of urology at Harborview Medical Center in Seattle, Wash.
Testosterone therapy (TTh) should be reserved for patients who (i) are symptomatic (ED or reduced libido) of testosterone deficiency45 and (ii) they have biochemical evidence of low testosterone (TT <8 nmol/L or 2.3 ng/mL). In men with borderline TT (8–12 nmol/L or 2.3–3.5 ng/mL), a TTh trial (for 3–6 months and continuation if effective) may be envisaged. While adding a PDE5 inhibitor can be considered in men who have not improved with TTh, the usual clinical scenario is to add TTh in patients who have not responded to PDE5 inhibitors. Improvement is dependent on the testosterone levels with better results being obtained at lower levels of TT.45 Despite evidence of benefit in patients with pre-existing cardiovascular conditions (angina or heart failure), it should be emphasized that TTh is not a medication with cardiovascular indications.
Abstract | PubMed | Scopus (136) | Google ScholarSee all References Other candidate mechanisms linking ED and cigarette smoking include hypercoagulability and increased platelet aggregation, increased release of free fatty acids and catecholamines, changes in NO synthetic pathways, and a possible direct toxic effect on vascular endothelium.13x13Chung, WS, Shim, BS, and Park, YY. Hemodynamic insult by vascular risk factors and pharmacologic erection in men with erectile dysfunction: Doppler sonography study. World J Urol. 2000; 18: 427–430
"Just because there is evidence doesn't mean it's good evidence," says Andrew McCullough, MD, associate professor of clinical urology at New York University Langone Medical Center in New York City, and one of the original clinical investigators for the ED drug Viagra (sildenafil). "And before men with ED start down the naturopathic route, it's smart to make sure that there isn't some underlying medical condition that needs to be corrected." Moreover, it is estimated that 30 million American men have erectile dysfunction, and 70% of cases are a result of a potentially deadly condition like atherosclerosis, kidney disease, vascular disease, neurological disease, or diabetes. Additionally, ED can also be caused by certain medications, surgical injury, and psychological problems.

Relaxation of erectile tissue requires nitric oxide from nonadrenergic-noncholinergic neurons and the endothelium.21 Penile tissue from diabetic men with ED demonstrates impaired neurogenic and endothelium-mediated relaxation of smooth muscle,22 increased accumulation of advanced glycation end products (AGEs),23 and upregulation arginase, a competitor with nitric oxide synthase for its substrate L-arginine.24 Normal responses to direct smooth muscle relaxants in most of these studies implies that the impairments are due to decreased synthesis, release, or activity of nitric oxide. The fundamental mechanisms mediating these changes are thought to be the same as for other diabetic complications: increased polyol pathway flux, intracellular accumulation of AGEs, activation of protein kinase C, and increased flux through the hexosamine pathway.25

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