BBR 2160 is a dihydropyridine derivative belonging to the group of the so-called tiampidine. BBR 2160 has calcium-antagonistic properties in cardiac tissue. Intracellular microelectrodes have been used to characterize the electrophysiological properties of BBR 2160 on guinea-pig papillary muscle and sheep Purkinje fibres. BBR 2160 (10(-7) and 10(-6) M) dose dependently decreased the contractility of driven papillary muscle and Purkinje fibre. This effect was associated with a lowering of the plateau phase and a shortening of action potential duration in papillary muscle.