ikan buntal

sape pernah makan ikan buntal a.k.a puffer fish a.k.a diodontid spp..pernah?..pernah?..
saye pon tak pernah..ekeke

ikan buntal is highly poisonous because it contains a neurotoxin known as tetrodotoxin (TTX).this toxin is highly concentrated mainly in gonads (telur), intestines, liver, and skin of this fish.as some people may already know, puffer fish is famous in japan as it is one of the japan's traditional delicacies called fugu. but do you know, between 1993-2006, there were 23 reported cases of puffer fish poisoning in Japan involving fishermen eating their catch of puffer fish. also, do you know that the incidence of TTX poisoning worldwide is around 250 cases in which its mortality rate is 60%. having said that, of 10 people poisoned by this neurotoxin, 6 of them will DIE! scary right?..hell yeah..but people still eat the fish.

about TTX
it is a product of bacteria called pseudomonas tetrodonis which may live in the fish. TTX is colourless, heat stable, and sparingly soluble in water. however, it is highly soluble in strong acidic solution. not only in puffer fish, TTX can also be found in blue-ringed octopus, certain newts, frogs, salamanders, and horse crabs. the most important thing, it has both neurotoxic, and cardiotoxic effects.
the lethal dose for TTX is between 8-20ug/kg.

the effects of TTX
when someone ingested TTX by consuming puffer fish, the symptoms may be shown 30 minutes after ingestion. sometimes, the symptoms may be delayed up to 4 hours after ingestion.
the effect starts with paresthesia or numbness of the lips and tongue. this may be followed by tingling sensation. he will also experince muscle weakness, nausea, vomiting, ataxia, and skin blistering. in severe cases, the victim may get, cyanosis, cardiac arrhythmia, general paralysis and eventually death. evans MH stated that the death of TTX poisoning is due to paralysis of diaphragm resulting in respiratory failure.

ok, now we know what someone will get when he/she ingested TTX. but how do these symptoms occur?

TTX selectively targets voltage-gated sodium channels which are important in generating action potentials. it binds to the extracellular pore on sodium channels resulting in action potential blockade. there are two types sodium channels involving TTX binding site. TTX resistance voltage-gated sodium channels and TTX sensitive voltage-gated sodium channels. TTX-r channel is primarily found in cardiac muscles whereas TTX-s channels dominate the rest tissues in the body such as skeletal muscles, brain, kidney, and so on. thus, the organs with the latter channels were compromised more than cardiac muscles. in skeletal muscle, failure in generating action potential will cause muscle paralysis.
although the brain is dominated by TTX-s sodium channels, the neurotoxin a.k.a TTX cannot cross blood brain barrier (BBB). therefore, brain is not hugely affected by TTX toxin. that's why the victim is conscious even though immobile. evans MH, 1969, reported that TTX levels are highest in kidney and heart of victim's body but lowest in blood and brain.

to be continued..


p/s: as a matter of fact, i was revising for my neurotox paper...and was trying to memorise about TTX...so yeah..this entry is boring.. ;-p