Ionic Basis of the Resting Membrane Potential in Cultured Rat Sympathetic Neurons

Neuroreport. 2002 Apr 16;13(5):585-91. doi: 10.1097/00001756-200204160-00010.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Ion Channels / physiology*
  • Membrane Potentials / physiology
  • Patch-Clamp Techniques
  • Rats
  • Superior Cervical Ganglion / cytology*
  • Superior Cervical Ganglion / physiology*

Substances

  • Ion Channels