Fig. 4.

Exogenous CP2 and SCP_b have significant effects on barium currents in B21. A1: B21 was held at −50 mV, and inward currents were induced by a 150-ms step to 0 mV. Currents were induced under control conditions (no peptide), in the presence of 1 μM CP2, after peptide washout, and in the presence of 2 mM Cd²⁺. Note the potentiating effect of the CP2. A2: group data for experiments in which currents were induced before, during, and after exogenous CP2 (n = 4). A3: currents were induced as described for A1 after preincubation in 10 μM nifedipine. Note the reduction in the magnitude of the current induced. A4: group data for experiments using the protocol shown in A3 (n = 3). B1: B21 was held at −50 mV, and inward currents were induced by a 150-ms step to 30 mV. Currents were induced under control conditions (no peptide), in the presence of 1 μM SCP_b, after peptide washout, and in the presence of 2 mM Cd²⁺. Note that SCP_b reduced the magnitude of the induced current. B2: group data for experiments in which currents were induced before, during, and after exogenous SCP_b (n = 5). B3: currents were induced as described for B1 after preincubation in 10 μM nifedipine. Note that the magnitude of the induced current is no longer altered by SCP_b application. B4: group data for experiments using the protocol shown in B3 (n = 3).