Voltage-clamp studies of a slow inward current in bullfrog sympathetic ganglion cells.
Voltage-dependent inward membrane currents of bullfrog sympathetic ganglion cells were analyzed with the voltage clamp method. Two distinct inward currents, a tetrodotoxin (TTX)-sensitive fast inward current (INa) and a TTX-insensitive slow inward current (Isi), were recorded in Ringer solution. The Isi was markedly depressed by removal of external Ca2+ and by the addition of Mn2+, Co2+ or D-600. This suggests that the Isi is, almost exclusively, due to Ca2+. These results indicate that under physiological conditions a Ca2+ influx is induced during initiation of action potentials in these ganglion cells.
D000818:Animals; D004594:Electrophysiology; D005728:Ganglia, Sympathetic / Q000502:physiology*; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology; D007552:Isotonic Solutions; D008564:Membrane Potentials; D011892:Rana catesbeiana / Q000502:physiology*; D000077331:Ringer's Solution; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D013997:Time Factors
D007473:Ion Channels; D007552:Isotonic Solutions; D013757:Tetraethylammonium Compounds; D013779:Tetrodotoxin; D019789:Tetraethylammonium; D000077331:Ringer's Solution