The Poison Tetrodotoxin
Duality
in nature is a peculiar thing. More often than not, bright beautiful
colors are often nature's way of saying "I am poisonous, stay away, do
not eat me!". Most predators know this and keep their distance, giving
wide berth to such organisms, save one: The Most Successful Predator on
this Planet. Man. Even the most successful predator on this
planet has its moments. 100-200 of people become ill each year after
eating "fugu", or pufferfish each year. Roughly half of these intoxifications
are fatal, even with immediate treatment.(Dr. Chein-Yuan Kao,
Brooklyn Medical Center) Anhydrotetrodotoxin
4-epitetrodotoxin, or Tetrodotoxin, as it is more easily referred to, is
10,000 times more lethal than cyanide. It is perhaps the most potent
toxin present in nature, save two others, which occur in bacteria.(Light,1998)
Tetrodotoxin is present in a other animals besides pufferfish, with the
blue-ringed octopus, harlequin frogs, and rough-skinned newts making the
list. Tetrodotoxin has even been isolated from certain strains of
algae, along with more marine life such as some snails, crabs and even
a type of flatworm. While tetrodotoxin is not exclusively owned by
just pufferfish, our chances of coming into contact with this poison is
surely greater with them.
Tetrodotoxin
affects the nervous system in such a way as to prevent the propagation
of nerve impulses. While it does not cross the blood-brain barrier,
it inhibits the ability of our nerves to send messages to other parts of
our body.
Confused?
Here's how it works. We all use electrical impulses to send messages
from our brain to other parts of our body to tell them to do things (yes,
I knew you knew that, but I had to start somewhere). These messages
fire from dendrite to axon within the nerve cells, ultimately reaching
their destination, in this case a muscle fiber (such as in the heart).
The "messages" involve the passage of sodium (Na+) ions and potassium (K+)
ions across the axon, along the nerve cell membrane. All you
really need to understand is that your nerves need both of these ions to
produce the electrical messages (action potentials). Ultimately,
this sends the right message to the muscle fiber shown in the diagram here.
Now, you have these two ions running up and down the cell interacting with
only each other and the cell membrane (simply put). Sodium and potassium
are moving in and out of the cell membrane (like the "skin" of the axon)
causing changes and carrying the electrical message. Again, your
body needs both of them in order to get the signal across. Tetrodotoxin
binds itself to the sodium ion, preventing it from moving in and out of
the membrane. As you can guess, this pretty much shuts down the entire
"message-sending" process, and the impulse never gets to its destination.
Now, knowing that we really need to do this (you said you did earlier,
right?) you can imagine what tetrodotoxin would do to us if it got into
really vital nerve cells.
Here are some
actual nerve cells. This image was taken from an electron microscope
observing stained nerve cells. A little tetrodotoxin and... well,
you get the picture. Actually, let's describe some of the symptoms
of fugu poisoning. So let's say your sushi chef had a little too
much sake the night before and goofed a bit while preparing your meal of
pufferfish--
The first
signs that something is awry is a slight numbness in the lips and tongue
(the sodium ions can't carry the messages, remember?). This numbness
soon increases and spreads to certain parts of your face and throat.
Some reported initial symptoms also included involuntary muscle spasms,
weakness, dizziness, and loss of speech.(2001,mednets.org)
There is excessive salivation and sweating, along with slowed heart rate
and a drop in body temperature. Victims soon experience respiratory distress,
marked by rapid, shallow breathing. The secondary stage of the poisoning
involves increased paralysis, to the point where even sitting becomes difficult.
From this point on it's pretty much downhill. After another increase
in paralysis, mental impairment and convulsions (yes, probably in that
order) ensue. This is followed by an inevitable case of cardiac arrhythmia.
Wait! It's not over yet. Do you remember earlier when I mentioned
that tetrodotoxin doesn't cross the brain-blood barrier? This basically
means that your brain, although composed of nerve cells, is not directly
affected by this toxin. There have been reports of fugu poisoning
survivors that they were completely lucid during the entire event, finally
recovering to tell the tale. (M. Lester, 1996) This may
come as no surprise to you voodoo enthusiasts out there (funny to see you
guys in the LFS buying shrimp and bloodworms), since your voodoo zombie
master (no disrespect, I don't know what else to call you?) uses tetrodotoxin
in his zombie powder. Yes, it's true, this toxin is the main ingredient
in zombie making practices in Haiti and West Africa. (Light,
1998) (If you're a zombie or just want more information,
go to google.com and search "Clarvius Narcisse", a zombie case documented
by ethnobotonists.)
But I digress--
Death usually
occurs within 4 to 6 hours, with a known range of about 20 minutes to 8
hours. If you've survived this ordeal, consider yourself lucky. Since
there is no antidote, medical professionals are left with no alternative
but to treat the symptoms. This is accomplished by removing remaining
toxins in your stomach with a charcoal lavage and techniques involving
life-support in an artificial respirator.
Let me reiterate,
bright colors usually mean "do not eat me".
