Abstract
High-speed countercurrent chromatography using a two-phase solvent system was found to be the method of choice for purifying an endogenous Ca2+ channel modulator. The solvent system composed of n-butanol, acetic acid and water (4:1:5) was most suitable for resolving the active material from other unknown substances of low molecular weight. Countercurrent chromatography proved useful in validating the presence in rat brain of an endogenous ligand for dihydropyridine-sensitive Ca2+ channels. Moreover, the degree of purity of the active material obtained by countercurrent chromatography is suitable for consecutive analysis by mass spectrometry or nuclear magnetic resonance.