A method for modulating calcium channels, increasing the density of calcium channels in vascular and cardiac tissue with no changes in inotropic or pressor response, comprising administering to a warm-blooded animal in need thereof a pharmaceutically-effective amount of a compound having formula (I) wherein R and R are independently hydrogen, C1-C4 alkyl, -CO-(C1-C6 alkyl), or -CH2Ar, -CO-Ar, wherein Ar is phenyl or substituted phenyl; R is selected from the group consisting of pyrrolidine, hexamethyleneimino, and piperidino; or a pharmaceutically-acceptable salt thereof.