Serotonin modulates calcium-dependent plateau of action potentials recorded from bull frog A-type sensory neurons which is omega-conotoxin GVIA-sensitive, but dihydropyridine-insensitive.
Tetraethylammonium-treated bull frog sensory neurons exhibit a calcium-dependent plateau on the falling limb of the action potential, which is reduced in duration by 5-HT. The portion of the calcium-dependent plateau which is reduced by 5-HT is blocked by omega-conotoxin GVIA but is not reduced by nifedipine or enhanced by Bay K 8644. The lack of effect of 5-HT, when retested after exposure of a previously 5-HT sensitive neuron to conotoxin favors the hypothesis that 5-HT reduces the duration of the calcium-dependent plateau by inactivating voltage-dependent calcium channels, rather than by increasing a voltage-dependent potassium current.
Scroggs
R S
RS
Department of Pharmacology, University of Illinois College of Medicine, Chicago 60612.
Anderson
E G
EG
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002118:Calcium / Q000502:physiology*; D004095:Dihydropyridines / Q000494:pharmacology*; D005727:Ganglia, Spinal / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008978:Mollusk Venoms / Q000494:pharmacology*; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology*; D009543:Nifedipine / Q000494:pharmacology; D011892:Rana catesbeiana / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology*; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D020866:omega-Conotoxin GVIA
D004095:Dihydropyridines; D008978:Mollusk Venoms; D013757:Tetraethylammonium Compounds; D012701:Serotonin; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; C038806:1,4-dihydropyridine; D020866:omega-Conotoxin GVIA; D009543:Nifedipine; D002118:Calcium