Erectile Dysfunction Part Two: Physical Causes
In part one of this series, I discussed erectile dysfunction (ED) and some of its psychological causes. The mental aspects of erection and arousal in men are murky at best, partially because each man has such a different relationship to arousal. Many myths and cultural values can aggravate the discomfort a man feels when he finds himself not always able to get an erection when he wants to.
In talking about the physical causes of erectile dysfunction, however, we encounter just as much cultural murkiness, as evidenced by the flurry of excitement, condemnation and profiteering — particularly around Viagra (sildenafil), the drug most commonly used to treat erectile dysfunction. However, in exploring the physical causes of erection and erectile dysfunction, we do have the advantage of fairly good science. That’s a cultural side effect of male erection and heterosexual intercourse ending in ejaculation tending to be thought of by science as the only real significant sexual activity. Regardless, the physical process of erection and the causes of erectile dysfunction are very well understood.
The Physical Process of Erection
As mentioned in part one of this series, erection occurs when a change in the muscles and nerves of the penis allow blood to flow into it but not to flow out. Cock rings restrict this outflow because the blood vessels by which blood leaves the penis are on the outside of the penis, close to the skin, where the influent blood vessels are on the inside. They therefore allow blood to flow in but inhibit it from flowing out. Cock rings can be helpful in maintaining erection (and many men find that they like the feeling of a cock ring), but if you’re experiencing frequent erectile dysfunction, please make sure you get checked out thoroughly by a doctor, because erection problems can be indicative of a larger health concern.
Physical Causes of Erection Problems
The most common cause of inhibited erection is when the blood flowing into the penis is not rich in oxygen. This causes an increase in the substance TGF-B1, which produces collagen, and a decrease in prostaglandin E1, which causes the relaxation of the smooth muscle whose relaxation allows blood to flow into the penis. Because TGF-B1 produces collagen, and collagen contributes to muscle wasting and the formation of scar tissue, too high a level of TGF-B1 will cause a loss of muscle elasticity in the penis, meaning the increased influent blood flow and decreased effluent is more difficult to achieve.
Low oxygen levels in the blood can be caused by a number of different factors, but the most common cause is ischemia, or the blockage of blood vessels. This is essentially the same medical condition that contributes to heart attack, often caused by a buildup of plaque on artery walls due to high levels of “bad” cholesterol in the blood. This process, atherosclerosis, reduces the available blood flowing through the body and therefore makes it difficult for the body to maintain optimal oxygen levels in the blood. It’s also one reason why older men, who are at greater risk for atherosclerosis, show greater frequency of erectile dysfunction.
Diabetes also contributes quite frequently to erectile dysfunction — as much as 40 percent of cases, according to the U.C. Davis Medical Center web site. Up to half of men with type 1 or type 2 diabetes report erection problems. While atherosclerosis often occurs with diabetes, diabetic nerve damage can also contribute to erectile dysfunction.
Similarly, high blood pressure (hypertension) can contribute to or cause erectile dysfunction, which was thought for may years to be caused more by the drugs used to treat hypertension than the condition itself. Recent research has suggested that hypertension itself may sometimes cause erectile dysfunction; regardless, it is a well-documented fact that drugs which lower blood pressure make it more difficult for many men to achieve erection. Newer drugs like angiotensin-converting enzyme (ACE inhibitors) and angiotensin-receptor blockers (ARBs) show a lower incidence of erectile side effects, and in some cases ARBs even seem to help erectile problems.
Lastly, men under treatment for depression may experience erectile difficulties. Most antidepressants cause some form of sexual side effects, which in some cases are more common in men than women. Some drugs inhibit erection, while others inhibit both erection and desire. Prozac (fluoxetine), Paxil (paroxetine) and similar drugs in the SSRI (selective serotonin reuptake inhibitors) class are often cited as causing sexual side effects; less commonly associated with sexual problems are Celexa (citalopram) and Welbutrin (bupropion) — and in some cases, Welbutrin is even used to treat lessened sexual desire.
These are a few of the most common physical causes of erectile dysfunction. Other causes include hormone abnormalities (including high estrogen levels), Parkinson’s disease, multiple sclerosis, prostate cancer and the treatments associated with those diseases and many others — including chemotherapy and radiation therapy.
In part three of this series, I’ll talk about specific treatments offered for ED — not just Viagra, but the many herbal supplements that claim to treat ED.