Picrotoxin is a poisonous crystalline plant compound, first isolated by Pierre Boullay in 1812. Found primarily in the fruit of the climbing plant Anamirta cocculus, it has a strong physiological action. It acts as a non-competitive channel blocker for the GABAA receptor chloride channels. It is therefore a channel blocker rather than a receptor antagonist. As GABA itself is an inhibitory neurotransmitter, infusion of picrotoxin has stimulant and convulsant effects. As such, picrotoxin can be used to counter barbiturate poisoning, that can occur during general anesthesia or during a large intake outside of the hospital. Picrotoxin is an equimolar mixture of two compounds, picrotoxinin (C15H16O6) and picrotin (C15H18O7). Picrotoxin is classified as an illegal performance-enhancing "Class 1 substance" by the American Quarter Horse Association.
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