Properties of whole cell currents in isolated olfactory neurons from the chilean toad Caudiverbera caudiverbera.
Isolated olfactory neurons from the chilean toad Caudiverbera caudiverbera were found to possess a same set of currents. Outward currents, made of a delayed rectifier and a Ca(2+)-dependent component, were blocked by replacing K+ by Cs+ in the patch pipette, in the presence of millimolar concentrations of tetraethylammonium and 4-aminopyridine in the external solution. Inward currents were made of a transient and a maintained component. The transient was abolished in the absence of external Na+ and was blocked by tetrodotoxin, with an apparent dissociation constant (KDapp) of 25.4 +/- 0.3 nM. The maintained inward currents were suppressed on removing external Ca2+, could be carried also by Ba2+, and were selectively blocked by Cd2+ (KDapp = 3.2 +/- 1.3 microM). A variety of agents found to block the maintained Ca2+ inward currents, including Co2+ and Ni2+, at millimolar concentrations, and nifedipine, verapamil, amiloride, and the amiloride analogue benzamil, at micromolar concentrations, were also effective in either modifying the gating of, or in blocking, the transient inward currents.
Delgado
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R
Centro de Estudios Cientificos de Santiago, Facultad de Ciencias, Universidad de Chile.
Labarca
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P
D000818:Animals; D001001:Anura; D002118:Calcium / Q000502:physiology; D002413:Cations, Divalent / Q000494:pharmacology; D002469:Cell Separation; D004553:Electric Conductivity; D004594:Electrophysiology; D008959:Models, Neurological; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009833:Olfactory Pathways / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009994:Osmolar Concentration
D002413:Cations, Divalent; D002118:Calcium