Characterization of voltage-gated potassium currents in dorsal root ganglion neurons of neonatal rats

J. Kim, Jun Jung Sung Jun Jung, Jeong Kim Sang Jeong Kim, J. Kim

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Abstract

Dorsal root ganglion (DRG) is composed of neuronal cell bodies of primary afferents with diverse functions. Various types of ion channels present on DRG neurons may reflect those functions. In the present study, voltage-gated potassium currents in DRG neurons of neonatal rats were characterized by whole-cell voltage clamp method. Two types of delayed rectifier and three types of transient potassium currents were identified according to their electrophysiological properties. The delayed rectifier currents were named I(Ke) (early inactivating) and I(Kl) (late inactivating). Steady state inactivation of I(Ke) began from -100 mV lasting until -20 mV. I(Kl) could be distinguished from I(Ke) by its inactivation voltage range, from -70 mV to +10 mV. Three transient currents were named I(Af) (fast inactivation), I(Ai) (intermediate inactivation kinetics), and I(As) (slow inactivation). I(Af) showed fast inactivation with time constant of 10.6±2.0 msec, I(Ai) of 36.9±13.9 msec, and I(As) of 60.6±2.9 msec at +30 mV, respectively. They also had distinct steady state inactivation range of each. Each cell expressed diverse combination of potassium currents. The cells most frequently observed were those which expressed both I(Kl) and I(Af), and they had large diameters. The cells expressing I(Ke) and expressing I(Ke), I(Ai), and I(As) usually had small diameters. Judging from cell diameter, capsaicin sensitivity or action potential duration, candidates for nociceptor were the cells expressing I(Ke), expressing I(Ke) and I(Ai), and expressing I(Ke) and I(As). The types and distribution of potassium currents in neonatal rat DRG were similar to those of adult rat DRG (Gold et al, 1996b).

Original languageEnglish (US)
Pages (from-to)613-624
Number of pages12
JournalKorean Journal of Physiology and Pharmacology
Volume1
Issue number6
Publication statusPublished - Dec 1 1997

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Keywords

  • Characterization
  • Dorsal root ganglion
  • Neonatal rat
  • Potassium current
  • Voltage clamp

ASJC Scopus subject areas

  • Physiology
  • Pharmacology

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