Figure 5. Effect of Cd²⁺, nifedipine, and efonidipine on Ca²⁺ currents in dissociated STN neurons.

50 μM Cd²⁺ (upper traces) and 10 μM nifedipine (middle traces) both show little inhibition of LVA Ca²⁺ current (elicited at –40 mV from a holding potential of –120 mV; left) yet substantial inhibition of HVA Ca²⁺ current (elicited at 0 mV from a holding potential of –80 mV; middle) in the same dissociated STN neuron. 5 μM efonidipine (lower traces) exerts substantial inhibition of both LVA (left) and HVA (right) Ca²⁺ currents in the same neuron. The average inhibitory effect on LVA Ca²⁺ currents (elicited at –40 mV) by 50 μM Cd²⁺ (n = 5), 100 μM Cd²⁺ (n = 4), 10 μM nifedipine (n = 4), and 5 μM efonidipine (n = 4) is shown in the right panel. Scale bars: 50 pA/5 ms.