Figure 4
Ca V 2.2 channel splice isoforms inhibited similarly by ziconotide. Ziconotide inhibits CaV2.2 channel currents in a dose-dependent manner. CaV2.2 cDNAs for each splice isoform were transiently expressed in tsA201 cells together with necessary auxiliary subunits. Calcium channel currents in cells expressing e37a and e37b-CaV2.2 splice isoforms were inhibited by increasing amounts of ziconotide applied to the bath. A, representative calcium currents in the presence of different concentrations of ziconotide for each splice isoform (e37a and e37b). Currents were activated by voltage step to 0 mV from a holding potential of -100 mV. B, Partial dose–response curve showing the potency of ziconotide to inhibit CaV2.2 calcium currents activated by a voltage-step to 0 mV, from cells expressing either e37a or e37b-CaV2.2 channels.