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|Section2= |Section3= }} Ryanodine is a poisonous alkaloid 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 muscular contractions. The effect of micromolar-level binding is paralysis. This is true for both mammals and insects. == See also == * Ryanoid, a class of insecticides with the same mechanism of action as ryanodine 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「ryanodine」の詳細全文を読む スポンサード リンク
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