Figure 9. Pharmacological dissection of HVA-I_Ca in zebrafish DRG neurons.

A, Left, Time courses of I_Ca 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_Ca 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. Right, superimposed current traces obtained at different time points during drug application (labeled as a–f). B, Bar graph representing the mean I_Ca 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. C, Effect of non-dihydropyridine Ca²⁺ channel agonist FPL 64176 (FPL) on I_Ca 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_Ca display neither an increase in macroscopic inward currents nor greatly prolonged trajectory of the tail currents (right panel).