Tetrodocain

Tetrodotoxin (also known as TTX) is a potent neurotoxin. Its name derives from Tetraodontiformes, an order that includes pufferfish, porcupinefish, ocean sunfish, and triggerfish; several of these species carry the toxin. Although tetrodotoxin was discovered in these fish and is most commonly associated with them, it is found in a wide variety of other animals.

Chemistry

Tetrodotoxin is a sodium channel blocker. It inhibits the firing of action potentials in neurons by binding to the voltage-gated sodium channels in nerve cell membranes and blocking the passage of sodium ions (responsible for the rising phase of an action potential) into the neuron. This prevents the nervous system from carrying messages and thus muscles from flexing in response to nervous stimulation.

Sources

Tetrodotoxin is found in two marine creatures – the blue-ringed octopus and the pufferfish. However, the toxin is not produced by the animals themselves but by a bacteria that is hosted by them.

Toxicity

Tetrodotoxin is extremely toxic. The median lethal dose for humans is around 2-3 milligrams. The toxin causes numbness, high blood pressure, and, in severe cases, cardiac arrest. There is no known antidote for tetrodotoxin.

Treatment

Treatment of tetrodotoxin poisoning is primarily supportive. The patient is monitored for respiratory failure and may require artificial respiration. If caught early, gastric lavage can remove some of the toxin. Activated charcoal can also be used to bind the toxin in the stomach and intestines.

See also

• Neurotoxin
• Pufferfish
• Blue-ringed octopus