It is established that diterpenoid alkaloid songorine in micromolar concentrations in the presence of ATP, activates like diazoxide and 1-O-benzoylnapelline, the mito KATP-channel (IC50 = 1.0 mu M) and also dose-dependently inhibits opening of the Ca2+ -dependent megapore of isolated rat liver mitochondria (IC50 = 35.2 +/- 3.1 mu M).