Stereoselectivity of NC-1100, a Ca-entry blocker.

1. Stereoselectivity of NC-1100 in Ca-entry blocking activity was tested in the guinea pig taenia caecum. 2. Racemic, (-)- and (+)-NC-1100 shifted the contraction-response curve of CaCl2 towards higher concentration in a parallel manner suggesting a competition. 3. (-)-NC-1100 was about 3 times as potent as (+)-NC-1100. 4. Potency of racemic NC-1100 was intermediate between those of (-)- and (+)-NC-1100.