title: Increase in neuroexcitability of unmyelinated C-type vagal ganglion neurons during initial postnatal development of visceral afferent reflex functions.
abstract: BACKGROUND
  Baroreflex gain increase up closely to adult level during initial postnatal weeks, and any interruption within this period will increase the risk of cardiovascular problems in later of life span. We hypothesize that this short period after birth might be critical for postnatal development of vagal ganglion neurons (VGNs).
  
  
  METHODS
  To evaluate neuroexcitability evidenced by discharge profiles and coordinate changes, ion currents were collected from identified A- and C-type VGNs at different developmental stages using whole-cell patch clamping.
  
  
  RESULTS
  C-type VGNs underwent significant age-dependent transition from single action potential (AP) to repetitive discharge. The coordinate changes between TTX-S and TTX-R Na(+) currents were also confirmed and well simulated by computer modeling. Although 4-AP or iberiotoxin age dependently increased firing frequency, AP duration was prolonged in an opposite fashion, which paralleled well with postnatal changes in 4-AP- and iberiotoxin-sensitive K(+) current activity, whereas less developmental changes were verified in A-types.
  
  
  CONCLUSIONS
  These data demonstrate for the first time that the neuroexcitability of C-type VGNs increases significantly compared with A-types within initial postnatal weeks evidenced by AP discharge profiles and coordinate ion channel changes, which explain, at least in part, that initial postnatal weeks may be crucial for ontogenesis in visceral afferent reflex function.
authors.affiliation: Department of Pharmacology, Harbin Medical University, Harbin, China.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Qian
authors.forename: Dong-Jie
authors.initials: DJ
authors.lastname: Liu
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Li-Min
authors.initials: LM
authors.lastname: Han
authors.forename: Mei
authors.initials: M
authors.lastname: Yuan
authors.forename: Jun-Nan
authors.initials: JN
authors.lastname: Li
authors.forename: Bing
authors.initials: B
authors.lastname: Xu
authors.forename: Xiao-Long
authors.initials: XL
authors.lastname: Lu
authors.forename: Pan-Xiang
authors.initials: PX
authors.lastname: Cao
authors.forename: Hao-Yan
authors.initials: HY
authors.lastname: Wang
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Pan
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Wang
authors.forename: Guo-Fen
authors.initials: GF
authors.lastname: Qiao
authors.forename: Bai-Yan
authors.initials: BY
authors.lastname: Li
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology; D000200:Action Potentials / Q000502:physiology*; D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D009413:Nerve Fibers, Myelinated / Q000502:physiology; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000502:physiology*; D026941:Sodium Channel Blockers / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D014630:Vagus Nerve / Q000502:physiology*; D017833:Visceral Afferents / Q000502:physiology*
chemical_list: D010455:Peptides; D026902:Potassium Channel Blockers; D026941:Sodium Channel Blockers; D013779:Tetrodotoxin; C064719:iberiotoxin; D015761:4-Aminopyridine
keywords: Action potential; Ion channel; Patch-clamp technique; Postnatal development; Visceral afferent