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VOLTAGE-DEPENDENT calcium (Ca2) channel currents in freshly dissociated adult guinea-pig jugular ganglion neurons were examined and characterized using the whole-cell patch-clamp technique. Electrophysiological analysis demonstrated a high-threshold current, but no low-threshold or T-type current. A fraction of the total Ca2current was inhibited by omega (ω)-conotoxin GVIA (Cg (in TX; 10 μM); the dihydropyridine antagonist nifedipine (NIF; 10 μM), inhibited a large fraction of the CgTX-insensitive current. The remaining CgTX/NIF-insensitive current was completely inhibited by ω-agatoxin IVA (AgIVA; 100 nM). These results demonstrated that the whole-cell Ca2channel current consisted only of N-, L-P-type components. Of these currents, only the L-type was partially inhibited by both histamine and carbachol (0.01–100 μM).