title: Kv1.3 channels regulate synaptic transmission in the nucleus of solitary tract.
abstract: The voltage-gated K(+) channel Kv1.3 has been reported to regulate transmitter release in select central and peripheral neurons. In this study, we evaluated its role at the synapse between visceral sensory afferents and secondary neurons in the nucleus of the solitary tract (NTS). We identified mRNA and protein for Kv1.3 in rat nodose ganglia using RT-PCR and Western blot analysis. In immunohistochemical experiments, anti-Kv1.3 immunoreactivity was very strong in internal organelles in the soma of nodose neurons with a weaker distribution near the plasma membrane. Anti-Kv1.3 was also identified in the axonal branches that project centrally, including their presynaptic terminals in the medial and commissural NTS. In current-clamp experiments, margatoxin (MgTx), a high-affinity blocker of Kv1.3, produced an increase in action potential duration in C-type but not A- or Ah-type neurons. To evaluate the role of Kv1.3 at the presynaptic terminal, we examined the effect of MgTx on tract evoked monosynaptic excitatory postsynaptic currents (EPSCs) in brain slices of the NTS. MgTx increased the amplitude of evoked EPSCs in a subset of neurons, with the major increase occurring during the first stimuli in a 20-Hz train. These data, together with the results from somal recordings, support the hypothesis that Kv1.3 regulates the duration of the action potential in the presynaptic terminal of C fibers, limiting transmitter release to the postsynaptic cell.
authors: Rammelkamp Center for Education and Research, MetroHealth Medical Center, Cleveland, OH 44109-1998, USA.
authors: Angelina
authors: A
authors: Ramirez-Navarro
authors: Patricia A
authors: PA
authors: Glazebrook
authors: Michelle
authors: M
authors: Kane-Sutton
authors: Caroline
authors: C
authors: Padro
authors: David D
authors: DD
authors: Kline
authors: Diana L
authors: DL
authors: Kunze
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001016:Aortic Bodies / Q000378:metabolism; D001703:Biophysics / Q000379:methods; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000235:genetics*; D066298:In Vitro Techniques; D051664:Kv1.3 Potassium Channel / Q000235:genetics / Q000378:metabolism*; D008297:Male; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques / Q000379:methods; D026902:Potassium Channel Blockers / Q000494:pharmacology; D017729:Presynaptic Terminals / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012604:Scorpion Venoms / Q000494:pharmacology; D026941:Sodium Channel Blockers / Q000494:pharmacology; D017552:Solitary Nucleus / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects; D013779:Tetrodotoxin / Q000494:pharmacology; D050599:Vesicular Glutamate Transport Protein 2 / Q000378:metabolism
chemical_list: D051664:Kv1.3 Potassium Channel; D026902:Potassium Channel Blockers; D012333:RNA, Messenger; D012604:Scorpion Venoms; D026941:Sodium Channel Blockers; D050599:Vesicular Glutamate Transport Protein 2; D013779:Tetrodotoxin; C077910:margatoxin