Pharmacology of AmCa_V4. (A) Representative current traces recorded with an oocyte expressing AmCa_V4 in response to a shortened activation protocol. AmCa_V4 current was not inhibited by 10 µM TTX. (B) Known blockers and agonists of Ca_V channels had no effect on AmCa_V4. (C) Representative current traces recorded with an oocyte expressing AmCa_V4 in response to a shortened activation protocol in the Ca²⁺ solution. After recording the original current level, the oocyte chamber was perfused with the Ca²⁺ solution supplemented with 100 µM cadmium and then with the Ca²⁺ solution supplemented with 100 µM zinc. (D) Average block of AmCa_V4 after the addition of different concentrations of cadmium and zinc to the extracellular solution (n = 3). The cumulative dose–response experiments were conducted separately for cadmium and zinc. Data are expressed as means ± SEM.