It may seem odd, that a drug whose claim to fame is fighting pain, rose to the level of superstar in the world of meds used to combat cardiovascular disease.
To understand what is happening we need to eaves drop on cell conversations.
Cells chit chat using the eicosanoid language
Cells are continuously chatting to the cells in the neighbourhood via the eicosanoid language.
Listening in on the cell chit chat is quite difficult, because cells whisper to one another so the chemicals only exist for a very brief period of time, at extremely low levels. Scientists are still trying to learn the language, but they have identified a number of these chemicals.
Some of the more well known chemicals in the language are
- Prostaglandins – PGE2, PGF
- Leukotrienes – LX1
- Thromboxanes – TX1
The language has lots of words each carrying its own particular message. Translating all of the words is very complex so to keep things simple, scientists just translate the gist of the conversation.
The conversation between the cells is either
- happy i.e. “everything is okay” – this message is communicated by “good” eicosanoids or
- very negative i.e. “I’m in trouble, help” – this message is communicated by “bad” eicosanoids
Platelets, also sometimes called thrombocytes, are actually not really cells at all, they are little bits that have broken off a giant cell called a megakarocyte.
Platelets are really a very special type of glue that is used to plug holes and hold things together. But in order for them to be useful, they need to be sticky when there is a hole and not sticky when there isn’t. They know what to do because they listen to the eicosanoids.
When they hear cells screaming because they are in trouble, they get all excited. They join in the chorus and start producing lots of thromboxanes. Scientists classify thromboxanes as “bad” eicosanoids because they are being produced when there is TROUBLE.
The thromboxanes help the platelets turn sticky and they start to join up with one another in a process called platelet aggregation, so they can plug up the hole.
Endothelial cells often in trouble in cardiovascular disease
The cells in people with cardiovascular disease tend to be sending out the message “Help I am in trouble” all the time because
- high blood pressure, creates pressure in the pipes which causes little tears in the blood vessels which need to be plugged and
- high sugar levels cut into the endothelial cells lining the blood vessels
The platelets are kept busy trying to “help”. The rush in to plug up “holes”
Platelet plugs block blood vessels
If the platelet clumping gets out of hand, it can end up blocking the blood vessel, which stops the oxygen supply to the cells and causes the surrounding cells to die.
How big the block is, and where the block is, determines what goes wrong
- in an ordinary blood vessel – the block is a thrombosis
- in a cardiac artery – the block is a myocardial infarction or heart attack.
- in a brain blood vessel – the block causes a stroke
Big blocks in the wrong place can KILL.
So how does aspirin work ?
Officially aspirin breaks an enzyme known as the cyclooxygenase enzyme.
It is a bit unusual to find a drug actually breaking an enzyme, most drugs just interfere with the functioning of the enzyme but aspirin really breaks the enzyme. Once aspirin meets up with the enzyme it no longer works. This is why aspirin works in heart disease and none of the other painkiller do.
Cyclooxygenase is one of the main enzymes producing the eicosanoids. It makes both good eicosanoids and bad eicosanoids depending on the cell type and membrane composition.PS. Diet influences the membrane composition.
Aspirin kills the cell chit chat temporarily
By breaking the cyclooxygenase enzyme – aspirin silences the cells. They just stop talking to each other.
Since no messages, good or bad, are being sent, the level of agitation in the cells lining the blood vessels largely goes unnoticed, temporarily.
But the gag on cell talking, only lasts a very short time, because aspirin doesn’t stick around in the body for very long. As soon as the aspirin has left the body, the body cells immediately make new enzyme and resume conversations.
Platelets are silenced permanently
The overall gag on cell talk, does mean that the platelets are less likely to pick up cries for help. But the cells will recover relatively quickly and start squealing, so this is not enough to protect from cardiovascular disease.
But because platelets are not really cells, they don’t have any way of replacing the destroyed cycloxygenase enzyme like regular cells. An encounter with aspirin means the platelet’s enzyme is broken. The platelets float around for the rest of their rather short lives, unable to glue anything. No working platelets means even if their are screams for help, the platelets can’t help because they cannot stick together to form a plug / clot.
No plug / clot means no blockages of blood vessels so you are less likely to have a heart attack or stroke.
|Diabetics should dump the baby aspirin since it’s not enough to prevent cardiovascular disease||Tweedle dum and tweedle dee lacked fat cell membrane synergy||Brushing your teeth is good for your heart|
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