1,4-Dihydropyridine activators in the tiamdipine series.

The pharmacologic and radioligand binding properties of 5-nitro analogs of the 1,4-dihydropyridine Ca2+ channel antagonist, tiamdipine (2-(2-aminoethylthio)methyl-3-carbomethoxy-5-carbomethoxy-6-m ethyl-4-(3-nitrophenyl)-1,4-dihydropyridine) and its N-formyl derivative have been measured in rat tail artery, guinea pig ileum and rat heart. The enantiomers of both analogs showed activator and antagonist properties, the latter being exhibited at lower concentrations.