Effects of pimozide on noradrenergic transmission in rabbit isolated ear arteries

Eur J Pharmacol. 1977 Nov 15;46(2):101-11. doi: 10.1016/0014-2999(77)90245-x.

Abstract

In the rabbit ear artery both dopamine and noradrenaline inhibit stimulation-induced (S-I) transmitter noradrenaline efflux. Pimozide, which is reported to be a specific dopamine receptor antagonist, was used to further study the effects of dopamine on transmitter efflux. In a concentration of 0.2 micrometer pimozide blocked the inhibition of S-I efflux produced by 0.5 micrometer dopamine but not that produced by 0.5 micrometer noradrenaline. In a concentration of 10 nM, pimozide enhances transmitter release and vasoconstrictor responses to sympathetic nerve stimulation; this may be due to blockade of feedback inhibition of transmitter release by endogenous dopamine. In a concentration of 1 micrometer, pimozide reduced transmitter release and vasoconstrictor responses to sympathetic nerve stimulation. Vasoconstrictor responses to noradrenaline and histamine are antagonized by pimozide in a noncompetitive manner.

MeSH terms

  • Animals
  • Anura
  • Arteries / innervation*
  • Cocaine / pharmacology
  • Dopamine / pharmacology
  • Drug Interactions
  • Electric Stimulation
  • Heart Atria / drug effects
  • Histamine / pharmacology
  • In Vitro Techniques
  • Norepinephrine / physiology*
  • Pimozide / pharmacology*
  • Rabbits
  • Sympathetic Nervous System / physiology
  • Synaptic Transmission / drug effects*
  • Vasoconstrictor Agents

Substances

  • Vasoconstrictor Agents
  • Pimozide
  • Histamine
  • Cocaine
  • Dopamine
  • Norepinephrine