Toxin-resistant calcium currents in embryonic mouse sensory neurons

Neuroscience. 1997 Sep;80(1):267-76. doi: 10.1016/s0306-4522(97)00101-2.

Abstract

We characterized toxin-insensitive calcium currents expressed by acutely dissociated embryonic dorsal root ganglion neurons. In the presence of 3 microM omega-conotoxin-GVIA, 3 microM nitrendipine and either 500 nM omega-agatoxin-IVA or 500 nM omega-conotoxin-MVIIC to inhibit N-, L- and P/Q-type currents, respectively, all neurons expressed two residual currents: a T-type and another which we referred to as toxin-resistant current. The toxin-resistant current (i) consisted of an inactivating and a sustained components, (ii) had a threshold of activation and a steady-state inactivation comprised between that of the T-type current and that of the other high-voltage-activated currents, (iii) had the same permeability for barium and calcium used as charge carriers, (iv) was highly sensitive to both cadmium and nickel; and (v) was insensitive to 500 microM amiloride which abolished the T-type at this concentration. The properties of the toxin-resistant current are very similar to those of the currents expressed in oocytes following injection of alpha(1E) subunits which we demonstrated to be present in these neurons. Therefore a component of the toxin-resistant current calcium channels in sensory neurons may be closely related to those calcium channels formed by alpha(1E) subunits.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium Channel Blockers / toxicity*
  • Calcium Channels / drug effects
  • Calcium Channels / physiology*
  • Embryo, Mammalian / drug effects
  • Embryo, Mammalian / physiology
  • Ganglia, Spinal / drug effects
  • Ganglia, Spinal / physiology*
  • Mice
  • Neurons, Afferent / drug effects
  • Neurons, Afferent / physiology
  • Patch-Clamp Techniques
  • Peptides / toxicity
  • Toxins, Biological / toxicity*
  • omega-Conotoxins*

Substances

  • Calcium Channel Blockers
  • Calcium Channels
  • Peptides
  • Toxins, Biological
  • omega-Conotoxins
  • omega-conotoxin-MVIIC