Functional Na+/K+ pump in rat dorsal root ganglia neurons

Neuroscience. 1999;93(2):723-9. doi: 10.1016/s0306-4522(99)00122-0.


Steady-state Na+/K+ pump current (Ip) in isolated adult rat dorsal root ganglia neurons was studied to determine if the plasma membrane Na+/K+ pump activity is uniform across the population of dorsal root ganglia neurons. Cells were voltage-clamped at -40 mV and holding current (Ih) was recorded using whole-cell patch-clamp techniques under conditions that stimulate the Na+/K+ pump (60 mM intracellular Na+ and 5.4 mM extracellular K+). Ip was defined as the 1 mM ouabain-sensitive fraction of Ih. Data suggest the existence of three subpopulations of dorsal root ganglia neurons having mean steady-state Ip densities of 1.6+/-0.1, 3.8+/-0.2 and 7.5+/-0.4 pA/pF. Neurons with small Ip had an average soma perimeter of 95+/-3 microm, while neurons with medium and large Ip density had significantly larger soma sizes (131+/-8 and 141+/-7 microm, respectively). Neurons with a large Ip density had a significantly lower specific membrane resistance (Rm; mean 4.0+/-0.3 kohm x cm2) than neurons with medium or small Ip density (19+/-6 and 31+/-6 kohm x cm2, respectively). Regardless of these differences, in all groups of neurons Ip had a low sensitivity to ouabain (Ip half inhibition by ouabain was observed at 80-110 microM). These data suggest that the Na+/K+ pump site density and/or its activity is not uniform throughout the dorsal root ganglia neuron population; however, this non-uniformity does not appear to relate to the functional expression of the different alpha isoforms of the Na+/K+ pump. The major functional Na+/K+ pump in the dorsal root ganglia neuron plasma membrane appeared to be the low ouabain affinity (alpha1) isoform.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Cell Size
  • Cells, Cultured
  • Electric Stimulation
  • Electrophysiology
  • Enzyme Inhibitors / pharmacology
  • Ganglia, Spinal / cytology
  • Ganglia, Spinal / enzymology*
  • Ganglia, Spinal / ultrastructure
  • In Vitro Techniques
  • Male
  • Membrane Potentials / physiology
  • Neurons / drug effects
  • Neurons / enzymology*
  • Neurons / ultrastructure
  • Ouabain / pharmacology
  • Patch-Clamp Techniques
  • Rats
  • Rats, Sprague-Dawley
  • Sodium-Potassium-Exchanging ATPase / antagonists & inhibitors
  • Sodium-Potassium-Exchanging ATPase / metabolism*


  • Enzyme Inhibitors
  • Ouabain
  • Sodium-Potassium-Exchanging ATPase