title: Ionic basis of the resting membrane potential in cultured rat sympathetic neurons.
abstract: The conductances which determine the resting membrane potential of rat superior cervical ganglia (SCG) neurons were investigated using perforated voltage- and current-clamp whole-cell techniques. The resting potential of SCG cells varied from -47 to -80 mV (-58.3 +/- 0.8 mV, n = 55). Blockade of M and h currents induced a depolarisation (7.4 +/- 0.7 mV, n = 22) and a hyperpolarisation (7.2 +/- 0.7 mV, n = 20) respectively; however, no correlation between the amplitude of these currents and the resting potential was found. The inhibition of the Na/K pump also induced membrane depolarisation (3.2 +/- 0.2 mV, n = 8). Inhibition of voltage-gated currents unmasked a voltage-independent resting conductance reversing at -50 mV. The reversal potential of the voltage-independent conductance, which included the electrogenic contribution of the Na/K pump, was strongly correlated with the resting potential (R = 0.87, p < 0.0001, n = 30). Ionic substitution experiments confirmed the existence of a voltage-independent conductance (leakage) with four components, a main potassium conductance, two minor sodium and chloride conductances and a small contribution of the Na/K pump. It is concluded that the resting potential of SCG cells strongly depends on the reversal potential of the voltage-independent conductance, with voltage-activated M and h currents playing a prominent stabilising role.
authors.affiliation: Section of Physiology, Department of Functional Biology, Faculty of Sciences, University of Vigo, Lagoas-Marcosende, 36200, Spain.
authors.forename: J Antonio
authors.initials: JA
authors.lastname: Lamas
authors.forename: Antonio
authors.initials: A
authors.lastname: Reboreda
authors.forename: Verónica
authors.initials: V
authors.lastname: Codesido
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials / Q000502:physiology; D018408:Patch-Clamp Techniques; D051381:Rats; D017783:Superior Cervical Ganglion / Q000166:cytology* / Q000502:physiology*
chemical_list: D007473:Ion Channels