Potassium currents contributing to action potential repolarization in dissociated cultured rat superior cervical sympathetic neurones.
Pharmacological blocking agents were used to assess the contributions of different K(+)-currents to spike-repolarization and early spike-afterhyperpolarization recorded in dissociated, tissue-cultured rat superior cervical sympathetic neurones using both patch-clamp and impalement microelectrode techniques. Effects of 4-aminopyridine (4-AP) and tetraethylammonium (TEA), in concentrations which selectively reduced the delayed rectifier current IK(DR) and Ca(2+)-activated K(+)-current IK(Ca, fast), respectively, indicated that IK(DR) made a significant contribution to both spike repolarization and spike afterhyperpolarization under all recording conditions, whereas the contribution of IK(Ca,fast) depended on the level of intracellular Ca(2+)-buffering. No evidence for a significant role for the transient current IK(A) could be adduced in these experiments.
Marsh
S J
SJ
Department of Pharmacology, University College London, U.K.
Brown
D A
DA
D015761:4-Aminopyridine / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002104:Cadmium / Q000494:pharmacology*; D019256:Cadmium Chloride; D002118:Calcium / Q000494:pharmacology*; D002478:Cells, Cultured; D002712:Chlorides / Q000494:pharmacology*; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005728:Ganglia, Sympathetic / Q000502:physiology*; D007700:Kinetics; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D002712:Chlorides; D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D002104:Cadmium; D004533:Egtazic Acid; D019789:Tetraethylammonium; D015761:4-Aminopyridine; D019256:Cadmium Chloride; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium