Voltage-gated potassium currents within the dorsal vagal nucleus: inhibition by BDS toxin.
Voltage-gated potassium (Kv) channels are essential components of neuronal excitability. The Kv3.4 channel protein is widely distributed throughout the central nervous system (CNS), where it can form heteromeric or homomeric Kv3 channels. Electrophysiological studies reported here highlight a functional role for this channel protein within neurons of the dorsal vagal nucleus (DVN). Current clamp experiments revealed that blood depressing substance (BDS) and intracellular dialysis of an anti-Kv3.4 antibody prolonged the action potential duration. In addition, a BDS sensitive, voltage-dependent, slowly inactivating outward current was observed in voltage clamp recordings from DVN neurons. Electrical stimulation of the solitary tract evoked EPSPs and IPSPs in DVN neurons and BDS increased the average amplitude and decreased the paired pulse ratio, consistent with a presynaptic site of action. This presynaptic modulation was action potential dependent as revealed by ongoing synaptic activity. Given the role of the Kv3 proteins in shaping neuronal excitability, these data highlight a role for homomeric Kv3.4 channels in spike timing and neurotransmitter release in low frequency firing neurons of the DVN.
Dallas
Mark L
ML
School of Medicine, University of Leeds, Leeds LS2 9JT, UK. m.l.dallas@leeds.ac.uk
Morris
Neil P
NP
Lewis
David I
DI
Deuchars
Susan A
SA
Deuchars
Jim
J
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D053444:Inhibitory Postsynaptic Potentials / Q000502:physiology; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009434:Neural Pathways / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009498:Neurotoxins / Q000633:toxicity*; D018408:Patch-Clamp Techniques; D024642:Potassium Channels, Voltage-Gated / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D051670:Shaw Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D017552:Solitary Nucleus / Q000166:cytology / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D014630:Vagus Nerve / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D000906:Antibodies; C492014:Kcnc4 protein, rat; D009498:Neurotoxins; D024642:Potassium Channels, Voltage-Gated; D051670:Shaw Potassium Channels