CALCIUM CURRENT CHARACTERIZATION IN DISSOCIATED ADULT GUINEA-PIG JUGULAR GANGLION NEURONS

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 Ca2+ current was inhibited by omega (omega)-conotoxin GVIA (Cg (inTX; 10 mu M); the dihydropyridine antagonist nifedipine (NIF; 10 mu M), inhibited a large fraction of the CgTX/NIF-insensitive current. The remaining CgTX/NIF-insensitive current was completely inhibited by omega-agatoxin IVA (AgIVA; 100 nM). These results demonstrated that the whole-cell Ca2+ channel current consisted only of N-, L-P-type components. Of these currents, only the L-type was partially inhibited by both histamine and carbachol (0.001-100 mu M).