No matter what the cause of erectile dysfunction, it is likely to cause feelings of stress and other emotional reactions. It’s also not uncommon for erection problems to cause tension in a relationship, particularly if one or both partners withdraws emotionally and the problem is not talked about. And it’s possible for a man’s renewed ability to have intercourse after a period of no sexual activity to stir up relationship issues.
Erectile dysfunction can occur as a side effect of medication taken for another health condition. Common culprits are high blood pressure meds, antidepressants, some diuretics, beta-blockers, heart medication, cholesterol meds, antipsychotic drugs, hormone drugs, corticosteroids, chemotherapy, and medication for male pattern baldness, among others.
The body’s source for nitric oxide production is the amino acid L-arginine, which is naturally found in many foods. The average American ingests about 3,000–5,000 mg of L-arginine per day, as it is an amino acid naturally contained in many foods. Meats of all varieties, nuts, and dairy products are rich in L-arginine, so the body is accustomed to intake levels of several thousand milligrams every day.
Your doctor may also choose to lower your dose of certain medications. Or your provider may switch the type of drug you’re taking if it’s interfering with your sex life. Some medicines used for managing blood pressure, insomnia, anxiety, depression, seizures and prostate problems increase the risk for erectile dysfunction. Beta-blockers (for high blood pressure), SSRIs (often used to treat depression) and the class of drugs called benzodiazepines (like Ativan, Xanax, Librium and Valium) are commonly tied to ED. You may want to speak to your doctor about this.
Now that we better appreciate the complex sequence of events necessary for erections to occur, it’s no surprise that testosterone alone yields less than perfect results. Erectile dysfunction represents more than just low testosterone, which is just one facet of the spectrum of dysfunctional phenomena that cause sexual dysfunction. Nonetheless, when testosterone is combined with popular drugs like Viagra®, success is enhanced to an even greater degree—orgasmic function improves, along with erectile capacity and libido.20 Testosterone also activates penile nitric oxide; ultrasound studies have demonstrated a 27% increase in arterial blood flow into the penis with testosterone supplementation.23
A number of drugs are known to cause ED in patients with DM (Table 1). For example, many EDDM patients are on antihypertensive medications. Replacement of thiazides or beta-blockers with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers may be sufficient to regain erectile ability.5 Furthermore, discontinuation of selective serotonin reuptake inhibitors, if these drugs are not essential for patient well-being, may be therapeutic. Careful monitoring following drug discontinuation will help to determine if ED is due to the medication or other underlying disorders. The benefits of continued drug therapy with these drugs should always be weighed against the likelihood of causing ED and impacting on the patient's QOL.
Another risk factor is that men with type 2 diabetes may produce less than normal amounts of testosterone, a condition called hypogonadism. A 2007 study found that one-third of men with type 2 diabetes had low testosterone levels. Those men were also more likely to have ED, though the link may have to do with weight, not diabetes per se. Being overweight or obese is a risk factor for hypogonadism.
Previous studies reported that there is a strong chance of future cardiac events when ED occurs in younger men compared with older men.11 Another study suggested that there is consistent association across age groups.12 A study of men with diabetes found that ED acts as an indicator of cardiovascular events after adjusting for other illnesses, psychological aspects and the usual cardiovascular risk factors.13 Another large-scale study comprising 25,650 men with pre-existing ED suggested that these men had a 75 % increased risk of peripheral vascular disease.14 Moreover, some studies demonstrated a relationship between ED score and number of diseased coronary arteries and plaque burden in coronary arteries.2,15
Sexual problems might mean you have a broken heart, literally. The most common sexual problem in men is erectile dysfunction (ED). ED affects up to 30 million men in the United States. Surprisingly, ED might be a sign of heart problems. It is important to discuss sexual health with your doctor. Not only can your doctor prescribe medications to improve sexual function, but together you may be able to prevent a major heart problem like a heart attack. This article outlines the steps that you should take if you think you have ED.
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.
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

Does drinking water improve erectile dysfunction? Erectile dysfunction or ED is a common concern for men. Everyday factors, such as hydration levels, may affect a person's ability to get or maintain an erection. Drinking water may, therefore, help some men with ED. In this article, learn about the link between hydration and ED, and other factors that can cause ED. Read now
• Blood Vessels: Diabetes damages blood vessels, especially the smallest blood vessels such as those in the penis. Diabetes can also cause heart disease and other circulatory problems. Proper blood flow is absolutely crucial to achieving erection. “Erection is a hydraulic phenomenon that occurs involuntarily,” says Arturo Rolla, MD, of Harvard University School of Medicine. “Nobody can will an erection!” Anything that limits or impairs blood flow can interfere with the ability to achieve an erection, no matter how strong one’s sexual desire.
Cardiovascular disease and erectile dysfunction (ED) are closely interrelated disease processes. Erectile dysfunction reportedly affects 10 million to 20 million men in the United States and more than 100 million men worldwide. Each year, about 500,000 persons in the United States survive a myocardial infarction, and an estimated 11 million have existing cardiovascular disease, making the issue of sexual function and cardiac disease relevant to many patients. We explore the relationship between ED and the presence of cardiovascular disease in the general population. We also review the prevalence and pathophysiological associations of ED and cardiovascular disease. The risks of sexual activity for patients with cardiovascular disease are discussed, as are prevention and treatment strategies for ED in this patient population.
Three FDA-approved oral medications, sildenafil, tadalafil, and vardenafil are available. These drugs are phosphodiesterase type 5 (PDE-5) inhibitors that can prolong levels of cGMP in tissue allowing improved smooth muscle relaxation, thus facilitating an erection. PDE-5 inhibitor drugs are effective in 56-63% of diabetic men with ED. More stringent glycemic control can improve these results. Men with testosterone deficiency may benefit from a combination of oral ED medication and testosterone supplementation.
Unfortunately, government agencies often are slow to respond to new scientific information and economic and political forces make it difficult for our population to receive clear information informing them that heart disease is nutritionally induced and totally avoidable with dietary excellence. Sadly, even the American Heart Association advocates a diet that has been shown to actually increase heart disease.
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].
Crossref | PubMed | Scopus (71) | Google ScholarSee all References However, a double-blind, placebo-controlled study of 22 middle-aged men with hypercholesterolemia treated for 6 weeks with pravastatin or lovastatin showed improved erectile function with both medications.54x54Kostis, JB, Rosen, RC, and Wilson, AC. Central nervous system effects of HMG CoA reductase inhibitors: lovastatin and pravastatin on sleep and cognitive performance in patients with hypercholesterolemia. J Clin Pharmacol. 1994; 34: 989–996

Severe testosterone deficiency, known as “hypogonadism,” is present in approximately 2–35% of men with erectile dysfunction.19 However, lesser degrees of deficiency are common, perhaps present in the majority, depending on the definition of “low” applied, the method of measurement, and the parameter being used to define testosterone (total, free, or bioavailable) deficiency.19,20 Most authorities agree that a total testosterone level below 300 ng/dL is clearly low, and that 300–400 ng/dL is low to low-to-normal. Most studies using testosterone replacement for erectile dysfunction have attempted to achieve blood levels of 450–850 ng/dL.
Experimental in vivo studies have implicated central and peripheral neuropathy, impaired neurotransmission, and endothelial dysfunction in the pathogenesis of diabetic ED.26,27 Copulatory behavior and penile reflexes are uniformly impaired 4–12 months after the onset of diabetes in the BB rat.26,27 McVary et al.26 found that peripheral neuropathy accounts for only part of the dysfunctional findings, and that spinal sexual reflexes were also severely impaired.
Erectile dysfunction is common in the CVD patient. It is an important component of the quality of life and it also confers an independent risk for future CV events. The usual 3-year time frame between the onset of ED symptoms and a CV event offers an opportunity for risk mitigation. Thus, sexual function should be incorporated into CVD risk assessment for all men. Algorithms for the management of patient with ED have been proposed according to the risk for sexual activity and future CV events. A comprehensive approach to cardiovascular risk reduction (comprising of both lifestyle changes and pharmacological treatment) improves overall vascular health, including sexual function. Proper sexual counselling improves the quality of life and increases adherence to medication. Testosterone assessment may be useful for both diagnosis of ED, risk stratification and further management. There are issues to be addressed, such as whether PDE5 inhibition reduces CV risk. Management of ED requires a collaborative approach and the role of the cardiologist is pivotal.
Figure. Progression of atherosclerosis. Endothelial dysfunction occurs early in atherosclerosis and prevents blood vessels from dilating properly. When the blood vessels that supply the penis are not able to dilate during sexual stimulation because of endothelial dysfunction, the penis cannot fill with blood, and the man develops erectile dysfunction. As atherosclerosis progresses, plaques build up in blood vessels and blood flow is slowed, further worsening erectile function. A heart attack occurs when an atherosclerotic plaque in a coronary artery ruptures, a blood clot forms over the plaque, and blood flow to the heart muscle is completely blocked. Atherosclerotic risk factors (black arrows) worsen cardiovascular health; modification of these risk factors (red arrows) improves cardiovascular health.
Sexual dysfunction is a common, underappreciated complication of diabetes. Male sexual dysfunction among diabetic patients can include disorders of libido, ejaculatory problems, and erectile dysfunction (ED). All three forms of male dysfunction can cause significant bother for diabetic patients and can affect their quality of life. Despite this, health care providers often do not specifically ask their male diabetic patients about sexual function. This results in considerable underdiagnosis because patients are often reluctant or embarrassed to initiate discussion of these issues themselves. By not recognizing sexual dysfunction as a common organic sequel-lae of diabetes that should be addressed and treated, providers are missing an important opportunity to improve their patients' daily existence and quality of life.
Diabetes occurs when you have too much sugar circulating in your bloodstream. There are two main types of diabetes: type 1 diabetes, which affects less than 10 percent of those who have diabetes, and type 2 diabetes, which accounts for over 90 percent of diabetes cases. Type 2 diabetes often develops as a result of being overweight or inactive. Approximately 30 million Americans have diabetes, and about half of them are men.
Abstract | Full Text | Full Text PDF | PubMed | Scopus (164) | Google ScholarSee all References Several double-blind, placebo-controlled studies have shown vardenafil to be more effective than placebo in the treatment of ED secondary to a wide range of other etiologies as well.71x71Hellstrom, WJ, Gittelman, M, Karlin, G..., and Vardenafil Study Group. Sustained efficacy and tolerability of vardenafil, a highly potent selective phosphodiesterase type 5 inhibitor, in men with erectile dysfunction: results of a randomized, double-blind, 26-week placebo-controlled pivotal trial. Urology. 2003; 61: 8–14
The safety of PDE5 inhibitors in patients with IHD has been shown in multiple trials. Arruda-Olson et al. investigated the safety of sildenafil during exercise stress tests in patients with IHD to ascertain whether the drug induces or exacerbates myocardial ischaemia. This was a prospective, randomised crossover study that demonstrated safety of sildenafil when given 1 hour before an exercise stress test.69 Another study that investigated 120 trials of sildenafil revealed that the rates of MI and cardiovascular death with sildenafil are as low as with placebo.70
Abstract | Full Text PDF | PubMed | Scopus (16) | Google ScholarSee all References These medications cause intracavernosal pressure changes in animal models, and human studies have noted deleterious effects on erectile function, decreased libido, and ejaculatory problems.42x42Weiss, RJ. Effects of antihypertensive agents on sexual function. Am Fam Physician. 1991; 44: 2075–2082

The vascular endothelium has an important role in angiogenesis and vascular repair by producing regulatory substances, including NO, prostaglandin, endothelins, prostacyclin and angiotensin II. These regulatory factors regulate the blood flow to the penis by controlling smooth muscle contractility and subsequent vasoconstriction and vasodilatation. Generally, in erectile tissue, increased blood flow through the cavernosal artery increases shear stress and produces NO, which further relaxes the vascular smooth muscles and increases blood flow in the corpora cavernosa.54 These events cause penile erection. However, in ED, endothelial NO synthesis is reduced and there is increased endothelial cell death (Figure 2).55
Erectile dysfunction usually precedes cardiovascular events by 3 to 5 years. Therefore, sexual function should be incorporated into cardiovascular disease risk assessment for all men. Recently, algorithms for the management of patients with erectile dysfunction according to the risk for sexual activity and future cardiovascular events were proposed[91]. A comprehensive approach to cardiovascular risk reduction (comprising of both lifestyle changes and pharmacological treatment) will result in significant benefits on overall vascular health, including sexual function. Proper sexual counselling will exert beneficial effects on the quality of life of hypertensive patients with erectile dysfunction and will improve adherence to antihypertensive drug therapy[91].
Logically, ED secondary to testosterone deficiency should be treated by testosterone replacement. Testosterone levels in men decrease with age.4 Both epidemiological and observational studies have demonstrated that reduced testosterone is associated with increased cardiovascular risk. One meta-analysis showed lower testosterone and higher 17β oestradiol as significant risk predictors despite adjustment for age and body mass index.4 Patients with coronary artery disease (CAD) have been found to have lower testosterone levels than controls, and there is inverse correlation between testosterone and the incidence of major cardiovascular disease (CVD).4 A significant negative correlation has been reported between total testosterone levels and Framingham risk score.4 However, it has been pointed out that ‘It is unclear if this is a causal association or due to low testosterone being a biomarker of poor health’.4 Testosterone replacement as a treatment for …
Ginkgo biloba. Known primarily as a treatment for cognitive decline, ginkgo has also been used to treat erectile dysfunction -- especially cases caused by the use of certain antidepressant medications. But the evidence isn't very convincing. One 1998 study published in the Journal of Sex & Marital Therapy found that it did work. But a more rigorous study, published in Human Pharmacology in 2002, failed to replicate this finding. "Ginkgo has come out of fashion in the past few years," says Ronald Tamler, MD, assistant professor of medicine and codirector of the men's health program at Mount Sinai Medical Center in New York City. "That's because it doesn't do much. I can say that in my practice, I have not seen ginkgo work -- ever."
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.
Crossref | PubMed | Scopus (71) | Google ScholarSee all References However, a double-blind, placebo-controlled study of 22 middle-aged men with hypercholesterolemia treated for 6 weeks with pravastatin or lovastatin showed improved erectile function with both medications.54x54Kostis, JB, Rosen, RC, and Wilson, AC. Central nervous system effects of HMG CoA reductase inhibitors: lovastatin and pravastatin on sleep and cognitive performance in patients with hypercholesterolemia. J Clin Pharmacol. 1994; 34: 989–996

In Eastern medicine, animal products are commonly used for their perceived health benefits. The philosophy “like nourishes like”, suggests that consuming the organ of an animal will bring benefits to the corresponding organ in one’s body is a common belief. Men seeking greater potency have turned to eating penises from goats, bull, deer, horses, seals and other mammals in the form of cooked dishes or herbal preparations. While there is no scientific evidence supporting this practice, the cultural beliefs remain strong and supplements containing extracts from animal penises are readily available in the form of capsules, often mixed with herbal compounds pitching similar erectogenic properties. A significant proportion of these potency-inducing supplements in Asia have been found to contain PDE5-inhibitors substrates such as tadalafil and sildenafil (30). However uncontrolled use of illicit PDE5-inhibitors under the guise of natural supplements remains a health threat to the general public.


In a 2005 study, three months of twice-daily sets of kegel exercises combined with biofeedback and advice on lifestyle changes, such as quitting smoking, losing weight, and limiting alcohol, worked far better than just giving the participants advice. “Wearing tight pants will affect impotence along with some other medical conditions like diabetes and heart disease,” which can also affect a man’s degree of impotence, Dr. Jennifer Burns, specializing in family practice with an emphasis on gastrointestinal health at the BienEtre Center, told Medical Daily.


Ischaemic heart disease (IHD), also known as coronary artery disease (CAD), is a predominant manifestation of cardiovascular disease (CVD). CVD is the leading cause of morbidity and mortality, accounting for 17.3 million deaths globally every year; this figure is expected to grow to 23.6 million by the year 2030. Eighty per cent of these deaths occur in lower- and middle-income countries.5 ED and IHD are highly prevalent and occur concomitantly because they share the same risk factors, including diabetes, hypertension, hyperlipidaemia, obesity and smoking.
Smoking is an independent risk factor for ED. Tobacco smoking causes direct toxicity to endothelial cells, including decreased eNOS activity, increased adhesion expression and impaired regulation of thrombotic factors.6 A meta-analysis of 19 studies by Tengs and Osgood suggested that 40 % of the impotent men studied were current smokers compared with 28 % who had never smoked.49
And yes, this may all seem easier said than done, when it comes to a condition that is more often than not the subject of jokes—or the cause of embarrassment. Talking to your doctor is the first step in dealing with this complication, which can wreak havoc on your quality of life. Keeping diabetes in check and enjoying a healthy lifestyle can make a huge difference in reducing ED risk, but if that isn't enough, there are successful treatments. Sex brings a range of physical and psychological benefits, whether you have diabetes or not. Preventing or reversing ED isn't just about sex—it's a step toward better health and a more satisfying life.

Penile implants - are generally used if physical damage (like an accident) makes the anatomical parts needed for an erection not work. These are inserted by surgery and can provide a permanent treatment choice if others fail to work. The implants can be semi-rigid or inflatable. They can be pretty expensive and are not usually available on the NHS.

Sexual dysfunction is a common, underappreciated complication of diabetes. Male sexual dysfunction among diabetic patients can include disorders of libido, ejaculatory problems, and erectile dysfunction (ED). All three forms of male dysfunction can cause significant bother for diabetic patients and can affect their quality of life. Despite this, health care providers often do not specifically ask their male diabetic patients about sexual function. This results in considerable underdiagnosis because patients are often reluctant or embarrassed to initiate discussion of these issues themselves. By not recognizing sexual dysfunction as a common organic sequel-lae of diabetes that should be addressed and treated, providers are missing an important opportunity to improve their patients' daily existence and quality of life.
Abstract | Full Text PDF | PubMed | Scopus (19) | Google ScholarSee all References However, there has been disagreement regarding the effects of diuretics on erectile function; many studies found that only rarely have these medications been implicated convincingly as the cause of a patient's ED.36x36Wein, AJ and Van Arsdalen, KN. Drug-induced male sexual dysfunction. Urol Clin North Am. 1988; 15: 23–31

On any matter relating to your health or well-being, please check with an appropriate health professional. No statement herein is to be construed as a diagnosis, treatment, preventative, or cure for any disease, disorder or abnormal physical state. The statements herein have not been evaluated by the Foods and Drugs Administration or Health Canada. Dr. Marchione and the doctors on the Bel Marra Health Editorial Team are compensated by Bel Marra Health for their work in creating content, consulting along with formulating and endorsing products.
Talk with your doctor about your sexual health. Do not be shy or embarrassed. Your doctor has probably dealt with this issue before. If your doctor is an older man, he might even have ED. First, your doctor will figure out what is causing your ED, which can usually be done just by talking with you. Next, your doctor will look for risk factors for atherosclerosis (the Table) by asking you questions, checking your blood pressure, and performing a few blood tests. Identifying and successfully treating atherosclerotic risk factors can reduce the chance of developing major vascular events (heart attacks and strokes).
Three FDA-approved oral medications, sildenafil, tadalafil, and vardenafil are available. These drugs are phosphodiesterase type 5 (PDE-5) inhibitors that can prolong levels of cGMP in tissue allowing improved smooth muscle relaxation, thus facilitating an erection. PDE-5 inhibitor drugs are effective in 56-63% of diabetic men with ED. More stringent glycemic control can improve these results. Men with testosterone deficiency may benefit from a combination of oral ED medication and testosterone supplementation.
We need to keep in mind that angioplasty and bypass surgery have some significant adverse outcomes, including heart attacks, stroke and death. These invasive procedures only attempt to treat a small segment of the diseased heart, usually with only a temporary benefit. The patients treated with angioplasty and bypass will continue to experience progressive disability and most often die a premature death as a result of their heart disease.
Abstract | Full Text PDF | PubMed | Scopus (29) | Google ScholarSee all References After controlling for diabetes mellitus, tobacco use, and hyperlipidemia, hypertension was not found to be an independent predictor of vasculogenic ED in 440 impotent men as measured by the PBI.7x7Virag, R, Bouilly, P, and Frydman, D. Is impotence an arterial disorder? a study of arterial risk factors in 440 impotent men. Lancet. 1985; 1: 181–184
ED is a common complication of diabetes and people with diabetes are also prone to developing cardiovascular complications.48 The risk of ED is relatively high in patients with known CVD. This was supported by a study of men with known CVD, in which ED was substantially predictive of all-cause mortality and the composite of CVD death, admission for heart failure, MI and stroke.17 Macroangiopathy, microangiopathy and endothelial dysfunction are among the mechanisms by which diabetes causes ED.
A sexually competent male must have a series of events occur and multiple mechanisms intact for normal erectile function. He must 1) have desire for his sexual partner (libido), 2) be able to divert blood from the iliac artery into the corpora cavernosae to achieve penile tumescence and rigidity (erection) adequate for penetration, 3) discharge sperm and prostatic/seminal fluid through his urethra (ejaculation), and 4) experience a sense of pleasure (orgasm). A man is considered to have ED if he cannot achieve or sustain an erection of sufficient rigidity for sexual intercourse. Most men, at one time or another during their life, experience periodic or isolated sexual failures. However, the term “impotent” is reserved for those men who experience erectile failure during attempted intercourse more than 75% of the time.
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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