Elevated potassium shortens action potential duration by altering outward currents in chick dorsal root ganglia neurons.
Dissociated embryonic chick dorsal root ganglion (DRG) neurons maintained in culture exhibit a mixed Na+/Ca2+ action potential. The characteristic "shoulder" on the repolarizing phase is due to the relatively prolonged inward Ca2+ current. DRG neurons grown in an elevated K+ medium (25 versus. 5 mM) lack the plateau phase of the action potential. Voltage-clamp analysis showed that this plastic change in action potential duration is not due to the loss of the inward Ca2+ current but is partly due to the appearance of a Ca2(+)-dependent, 4-aminopyridine-(4-AP)-sensitive transient outward current. Faster activation of the purely voltage-dependent delayed rectifier outward current also contributes to the rapid repolarization observed in neurons cultured in elevated K+ medium.
Yang
J
J
Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110.
Zorumski
C F
CF
D015761:4-Aminopyridine / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002118:Calcium / Q000502:physiology*; D002478:Cells, Cultured; D002642:Chick Embryo; D005727:Ganglia, Spinal / Q000196:embryology / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology / Q000502:physiology*; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D013757:Tetraethylammonium Compounds; D013779:Tetrodotoxin; D015761:4-Aminopyridine; D011188:Potassium; D002118:Calcium