Histamine potentiates neuronal excitation by blocking a calcium-dependent potassium conductance

Agents Actions. 1984 Apr;14(3-4):534-7. doi: 10.1007/BF01973865.

Abstract

Histaminergic neurones send their axons to the whole forebrain. The diffuse projection is consistent with a modulatory role of these pathways. In hippocampal slices from rats a mechanism for this modulation is described, on pyramidal neurones of the CA 1 area: Strong excitations induced by intracellular current injection, ionophoretic administration of glutamate or synaptic stimulation normally restrict themselves by the activation of the calcium-dependent potassium current (gK(Ca) ). This current causes a long lasting afterhyperpolarization and an accommodation of firing. Their block by histamine and impromidine (reversed by metiamide and cimetidine) leads to a profound potentiation of excitatory signals. It is suggested that HA, through H2 receptors, accelerates the removal of intracellular free Ca++ ions.

MeSH terms

  • Animals
  • Calcium / physiology*
  • Histamine / pharmacology*
  • Imidazoles / pharmacology
  • Impromidine
  • In Vitro Techniques
  • Membrane Potentials / drug effects
  • Neural Conduction / drug effects*
  • Neurons / drug effects
  • Neurons / physiology
  • Potassium / physiology*
  • Rats
  • Synaptic Transmission / drug effects

Substances

  • Imidazoles
  • Histamine
  • Impromidine
  • Potassium
  • Calcium