Modulation of a transient outward current in serotonergic neurones by alpha 1-adrenoceptors

Nature. 1985 Jun;315(6019):501-3. doi: 10.1038/315501a0.


The excitability of various neurones in the mammalian central nervous system (CNS), ranging from motoneurones to serotonergic neurones, is enhanced by alpha 1-adrenoceptor agonists. Excitations mediated via alpha 1-adrenoceptors are associated with a slow depolarization and an increase in input resistance, probably resulting from a decrease in resting potassium conductance. However, the involvement of voltage-dependent transient currents in mediating alpha 1 excitatory effects has not been evaluated. An early transient outward current has been described which is important in regulating the frequency of repetitive firing; it is activated by depolarizing voltage steps from potentials more negative than rest and blocked by 4-aminopyridine. This current, which has been termed 'IA', was found originally in invertebrates and subsequently in various vertebrate neurones. The present single-electrode voltage-clamp study demonstrates an early transient outward current (IA) in serotonergic neurones which is suppressed by noradrenaline and the alpha 1-agonist phenylephrine; a suppression of IA may account in part for the acceleration of pacemaker activity induced by alpha 1-agonists in serotonergic neurones.

Publication types

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

MeSH terms

  • Animals
  • Cadmium / pharmacology
  • Calcium / physiology
  • Cells, Cultured
  • Electric Conductivity
  • Ion Channels / physiology*
  • Kinetics
  • Norepinephrine / pharmacology
  • Phenylephrine / pharmacology
  • Potassium / physiology*
  • Prazosin / pharmacology
  • Raphe Nuclei / physiology*
  • Rats
  • Receptors, Adrenergic, alpha / drug effects
  • Receptors, Adrenergic, alpha / physiology*
  • Serotonin / physiology*


  • Ion Channels
  • Receptors, Adrenergic, alpha
  • Cadmium
  • Phenylephrine
  • Serotonin
  • Potassium
  • Calcium
  • Norepinephrine
  • Prazosin