Ryanodine

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Ryanodine

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MeSH	Ryanodine
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Ryanodine is a poisonous diterpenoid found in the South American plant Ryania speciosa (Salicaceae). It was originally used as an insecticide.

The compound has extremely high affinity to the open-form ryanodine receptor, a group of calcium channels found in skeletal muscle, smooth muscle, and heart muscle cells. It binds with such high affinity to the receptor that it was used as a label for the first purification of that class of ion channels and gave its name to it.

At nanomolar concentrations, ryanodine locks the receptor in a half-open state, whereas it fully closes them at micromolar concentration. The effect of the nanomolar-level binding is that ryanodine causes release of calcium from calcium stores as the sarcoplasmic reticulum in the cytoplasm, leading to massive muscle contractions. The effect of micromolar-level binding is paralysis. This is true for both mammals and insects.

See also

• Diamide insecticides, a class of insecticides with the same mechanism of action as ryanodine
• Ryanodine receptor
• Dihydropyridine channel

Further reading

• Bertil Hille, Ionic Channels of Excitable Membranes, 2nd edition, Sinauer Associates, Sunderland, MA, 01375, Template:ISBN