Pharmacological dissection of HVA-<i>I_Ca</i> in zebrafish DRG neurons.

<p><b><i>A</i></b>, <i>Left</i>, Time courses of <i>I_Ca</i> amplitude during serial application of nifedipine (10 µM), ω-agatoxin IVA (0.5 µM), ω-conotoxin GVIA (3 µM), SNX-482 (300 nM) and CdCl₂ (100 µM). <i>I_Ca</i> was evoked every 10 s by 70 ms test pulses to 0 mV from a holding potential of −80 mV. The horizontal bars indicate the duration of drug application. <i>Right</i>, superimposed current traces obtained at different time points during drug application (labeled as a–f). <b><i>B</i></b>, Bar graph representing the mean <i>I_Ca</i> inhibition (%) produced by application of the indicated antagonists or toxins. Error bars represent s.e.m. The number of neurons tested is indicated in parentheses. <b><i>C</i></b>, Effect of non-dihydropyridine Ca²⁺ channel agonist FPL 64176 (FPL) on <i>I_Ca</i> in DRG neurons. FPL (1 µM) was applied to rat superior cervical ganglion (SCG) neurons as a positive control (left panel). Note that FPL applied to zebrafish DRG <i>I_Ca</i> display neither an increase in macroscopic inward currents nor greatly prolonged trajectory of the tail currents (right panel).