Phencyclidine blocks two potassium currents in spinal neurons in cell culture.
We studied the effects of phencyclidine (PCP) on the transient and delayed outward K+ currents recorded from spinal cord neurons grown (10-20 days) in cell culture. Sodium channels were blocked with tetrodotoxin (1 microM) and solutions containing low calcium concentrations in the presence of Mg2+ or Co2+ (5 mM) were used to reduce Ca2+ currents. PCP decreased the amplitude and prolonged the decay phase of the action potentials recorded at a holding potential of -70 mV. PCP (0.1-0.5 mM) was more effective than tetraethylammonium (TEA) or 4-aminopyridine (4-AP) in reducing both transient and delayed currents. The amplitude of the transient current during control experiments was always larger than that of the delayed current. It appeared that 4-AP (5 mM) was more potent in blocking the transient current, while TEA (10 mM) modified the delayed current more effectively. Both currents were also reduced by about 10% when the cell soma was perfused with Co2+. This suggested that a small fraction of the total outward current is a Ca2+-activated K+ current. The PCP-induced blockade of K+ currents in central neurons coupled with the profound synaptic effects of the drug may provide the basis for explaining the psychopathology of this hallucinogenic agent.
D015761:4-Aminopyridine; D000631:Aminopyridines / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D004622:Embryo, Mammalian; D007473:Ion Channels / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010622:Phencyclidine / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D000631:Aminopyridines; D007473:Ion Channels; D013757:Tetraethylammonium Compounds; D015761:4-Aminopyridine; D010622:Phencyclidine; D011188:Potassium