Electrophysiologic study of Lercanidipine and its enantiomers.

Lercanidipine is a new dihydropyridine (DHP) derivative with calcium antagonistic properties. In vitro and in vivo experiments have shown that it relaxes vascular musculature without exerting negative inotropic effects. The two ester groups present in positions 3 and 5 of the DHP ring lead to the existence of two enantiomers. We studied the electrophysiologic properties of lercanidipine and its enantiomers in multicellular preparations (i.e., rabbit and guinea pig papillary muscles) and patch-clamped isolated guinea pig ventricular myocytes. Lercanidipine (1 μM) affected neither action potential characteristics nor contraction amplitude of papillary muscles. It did not reduce sodium current or L-type calcium current (ICa) recorded from cells kept at a normal polarized membrane potential (-80 mV), both at low (0.2 Hz) and high stimulation frequency (1 Hz). (R)-Lercanidipine decreased (10.6 ± 1.6 vs. 12.1 ± 1.2 pA/pF; p < 0.05) and (S)-lercanidipine increased ICa (17.1 ± 1.0 vs. 12 8 ± 0.9 pA/pF;p