Noise of the slowly inactivating Na current in suprachiasmatic nucleus neurons.
Slow depolarization induces a riluzole-sensitive persistent Na current (INa,P) in several types of neurons and a pharmacologically similar slowly inactivating Na current (INa,S) in rat suprachiasmatic nucleus neurons. In isolated suprachiasmatic nucleus neurons, INa,S fluctuations were analyzed to characterize the Na channel responsible for INa,S. The single-channel current near resting potential was -0.53+/-0.04 pA in an external solution containing 151 mM Na+ and 5 mM Na+ in the patch pipette. Tetrodotoxin completely blocked INa,S and single-channel current noise; 25 microM riluzole also suppressed INa,S and current noise by about 80% without a significant effect on mean single-channel current. The data suggest that single-channel noise is due to the opening of channels mediating INa,S with a conductance of about 3.4 pS.
Kononenko
Nikolai I
NI
Department of Biomedical Sciences, Anatomy and Neurobiology Section, Colorado State University, Fort Collins, CO 80523, USA.
Dudek
F Edward
FE
D000818:Animals; D004558:Electric Stimulation / Q000379:methods; D004560:Electricity; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D016014:Linear Models; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques / Q000379:methods; D051381:Rats; D019782:Riluzole / Q000494:pharmacology; D026941:Sodium Channel Blockers / Q000494:pharmacology; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology*; D013493:Suprachiasmatic Nucleus / Q000166:cytology*; D013779:Tetrodotoxin / Q000494:pharmacology
D018691:Excitatory Amino Acid Antagonists; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D013779:Tetrodotoxin; D019782:Riluzole