A hyperpolarization-activated cation current (Ih) contributes to resting membrane potential in rat superior cervical sympathetic neurones

Pflugers Arch. 1998 Aug;436(3):429-35. doi: 10.1007/s004240050653.

Abstract

Using perforated-patch voltage-clamp recording, a prominent hyperpolarization-activated inward cation current (Ih) has been identified in dissociated, cultured and replated, superior cervical sympathetic (SCG) neurones from 17-day-old rats. Ih was identified as a slowly activated inward current on hyperpolarizing from -60 mV, with an extrapolated null potential (in 3 mM [K+]out) of -42 mV. The activation range for Ih was -40 to -100 mV, with a half-activation voltage (V0.5) of -63 mV. The current was suppressed by 1 mM Cs+ but not by 1 mM Ba2+. The reversal potential for the current change induced by Cs+ agreed with the null potential for Ih. Ih conferred strong inward rectification to the current-voltage curve negative to -55 mV in both voltage-clamp and current-clamp recording. This inward rectification was reduced by 1 mM Cs+. In a sample of eight cells with initial resting membrane potentials between -51 and -64 mV, Cs+ increased the resting potential of all cells by between 2.5 and 21 mV. These results indicate that Ih contributes a tonic inward (depolarizing) component to the maintenance of the resting membrane potential in SCG neurones.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Cyclic Nucleotide-Gated Cation Channels
  • Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels
  • Ion Channels / physiology*
  • Kinetics
  • Membrane Potentials / physiology
  • Nerve Tissue Proteins / physiology*
  • Neurons / physiology*
  • Patch-Clamp Techniques
  • Potassium Channels
  • Rats
  • Superior Cervical Ganglion / cytology
  • Superior Cervical Ganglion / physiology*

Substances

  • Cyclic Nucleotide-Gated Cation Channels
  • Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels
  • Ion Channels
  • Nerve Tissue Proteins
  • Potassium Channels