[lit-ideas] Re: Pharma Pills
- From: "Andreas Ramos" <andreas@xxxxxxxxxxx>
- To: <lit-ideas@xxxxxxxxxxxxx>
- Date: Fri, 3 Jun 2005 00:04:19 -0700
>> These pills work by constricting the blood vessels.
>
> Actually, they work by relaxing the relevant smooth muscle tissue
> allowing an _increased_ flow of arterial blood to the penis. It's true
> that the (relevant) veins constrict during an erection but this happens
> in any case.
Actually, it's even more complicated. It works by blocking an enzyme, which
leads to the
results that Robert described. I looked it up and found the following (below).
yrs,
andreas
www.andreas.com
The sildenafil citrate enters the bloodstream and flows throughout the body.
The sildenafil
citrate attaches to the PDE5 enzyme in his penis and disables most of it. When
the man
becomes sexually aroused, the brain sends the normal message to the NANC cells
in his penis,
which produce nitric oxide as usual. The nitric oxide creates cGMP, which
starts relaxing
the arteries in his penis. Since the PDE5 has been disabled, the cGMP in the
penis does not
break down. Instead, it builds up and lets the arteries in the penis fully
dilate. His penis
inflates with blood, and the man gets a full erection.
Viagra has several side effects. The first problem comes because Viagra happens
to have a
spill-over effect. It blocks PDE5 (an enzyme), but it also has an effect on
PDE6. It turns
out that PDE6 is used in the cone cells in the retina, so it can have an effect
on color
vision. Many people who take it notice a change in the way they perceive green
and blue
colors, or they see the world with a bluish tinge for several hours. For this
reason, pilots
cannot take it within 12 hours of a flight. The second problem comes for people
who are
taking drugs like nitroglycerin for angina. Nitroglycerin works by increasing
nitric oxide,
and it helps with angina by opening up the arteries that supply the heart with
oxygen. If
you take nitroglycerin and Viagra together, the increased nitric oxide plus the
blocking of
PDE5 can lead to problems. Other problems with Viagra can include little things
like
headaches (the drug, as a side effect in some men, opens up arteries in the
brain's lining
and causes excess pressure) and big things like heart attacks. The possibility
of heart
attacks is one reason why Viagra is a prescription drug rather than an
over-the-counter drug
like aspirin. Occasional patients who take Viagra® get painful, long-lasting
erections and
have to see a doctor to solve the problem. Finally, there is some concern that
some men,
especially younger men who take Viagra recreationally and who don't really need
it for
physical reasons, may end up with a dependency on the drug. That is, they may
become unable
to maintain an erection without taking Viagra.
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