ryanodine

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, ...