Ryanodine series

The general mechanism of Ca2+ wave propagation is believed to be as follows. An event occurs that results in a small rise of intracellular Ca2+ near an SR release receptor (either ryanodine receptor or inositol-1,4,5-trisphosphate [InsPs] receptor). The release of SR Ca2+ results in a local increase of cytoplasmic Ca2+. The nascent cytoplasmic Ca2+ then diffuses to adjacent release sites, causing further SR release. This process is a regenerative process and will remain so as long as the receptors are functional and the SR Ca2+ stores are sufficient. The Ca2+ wave can then be envisioned as a series of SR Ca2+ release events that are dependent upon local Ca2+ concentrations, receptor function, receptor density and diffusion of cytoplasmic Ca2+. The rate of propagation of the Ca2+ wave is possibly dependent upon any of these processes. 

O-acetate (162), which possesses a bridgehead double bond, was established by X-ray analysis. The structures of the congeners were then related to this by a series of spectral correlations. Cinnzeylanine (163) and its desacetoxy alcohol, cinnzeylanol, are insecticidal polyhydroxylated pentacyclic diterpenoids, which were isolated from Cinnamonum zeylanicum. Their structure, which is similar to that of ryanodine, was established by X-ray analysis. 

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