Inhibitory effect of UK 14,304 on ICa2+ in the presence of ω-agatoxin IVA (ATX), a P/Q-type channel toxin. A, UK 14,304 inhibited ICa2+ in the presence ATX. ICa2+ was activated by depolarizing the membrane potential from −70 mV to −10 mV. B, UK14,304 inhibits ICa2+ in the presence of ATX. Currents recorded in the presence of ATX and UK 14,304 were normalized to the control current in the same neuron. ATX alone reduced ICa2+ significantly (P < 0.05). In the presence of ATX, UK 14,304 (1 μM) further inhibited ICa2+ (P < 0.05). The inhibitory effect of UK 14,304 was reversible by washing with ATX-containing Krebs’ solution (n = 4).