Fig. 2.
Selectivity of pharmacological responses of Cav subtypes to dihydropyridine compounds. (A) Representative current traces illustrating effects of nifedipine and BAY K8644 on Cav1.2 (i) and Cav2.2 (ii) channels. The currents were elicited with test pulses to 10 mV (Cav1.2) and 30 mV (Cav2.2); the holding potential was −90 mV with 60-s CP to −50 mV. (B) Dose–response curves of the compounds effect on Cav1.2 (i) and Cav2.2 (ii) channels. Data presented as mean±SD; n=4. Data were fit to the Hill equation with coefficient in the range 0.6–2.0. Nifedipine inhibited Cav1.2 channels (IC50=0.016 μM) and had no effects on Cav2.2 channels. BAY K8644 produced twofold potentiation of Cav1.2 channels (EC50=0.006 μM), but inhibited Cav2.2 channel (IC50=14.3 μM).