A major role for calcium-dependent potassium current in action potential repolarization in adrenal chromaffin cells.
To determine the extent which Ca dependent K current (IKCa) contributes during an action potential (AP), bovine chromaffin cells were voltage-clamped using a pre-recorded AP as the command voltage waveform. Based on (1) differential sensitivity of IKCa and Ca-independent K current (IK) to tetraethylammonium; (2) measurements of AP currents under conditions where Ca activation of IKCa had been abolished; and (3) blockade by charybdotoxin, IKCa comprised 70-90% of the outward K current during AP repolarization. In addition, observations are made concerning the form of AP-evoked Ca current.
Pancrazio
J J
JJ
Department of Anesthesiology, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
Johnson
P A
PA
Lynch
C
C
D000200:Action Potentials / Q000502:physiology*; D000313:Adrenal Medulla / Q000166:cytology*; D000818:Animals; D002118:Calcium / Q000502:physiology*; D002417:Cattle; D002460:Cell Line; D018999:Charybdotoxin; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000502:physiology*; D012604:Scorpion Venoms; D013757:Tetraethylammonium Compounds; D013779:Tetrodotoxin
D015221:Potassium Channels; D012604:Scorpion Venoms; D013757:Tetraethylammonium Compounds; D018999:Charybdotoxin; D013779:Tetrodotoxin; D002118:Calcium