Actions of noradrenaline on myenteric neurons in the guinea pig gastric antrum

J Auton Nerv Syst. 1992 Nov;41(1-2):67-77. doi: 10.1016/0165-1838(92)90128-4.


We used intracellular electrophysiological recording to study the actions of noradrenaline on myenteric neurons in the guinea pig gastric antrum. Noradrenaline caused a dose-dependent inhibition of the stimulus-evoked cholinergic fast excitatory postsynaptic potentials (EPSPs). Noradrenaline had no effect on the postsynaptic response to acetylcholine, suggesting a presynaptic site of action. The slow EPSP was also presynaptically inhibited by noradrenaline. In only 5% of the neurons, noradrenaline caused a postsynaptic depolarization, accompanied by increased input resistance and enhanced excitability. Studies with adrenergic antagonists and agonists revealed that the presynaptic inhibitory effect was mediated by an alpha 2-receptor, while the postsynaptic excitatory effect seemed to be mediated by an alpha 1 receptor. We conclude that noradrenaline inhibits neurotransmitter release from cholinergic and non-cholinergic nerve terminals in the myenteric plexus of the antrum and that it excites a subpopulation of antral neurons. Both mechanisms may contribute to the neurally mediated inhibitory action of noradrenaline on gastric contractility.

Publication types

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

MeSH terms

  • Acetylcholine / pharmacology
  • Animals
  • Clonidine / pharmacology
  • Gastrointestinal Motility / drug effects
  • Guinea Pigs
  • In Vitro Techniques
  • Male
  • Membrane Potentials / physiology
  • Muscle Contraction / physiology
  • Myenteric Plexus / cytology*
  • Myenteric Plexus / drug effects
  • Neurons / drug effects*
  • Norepinephrine / pharmacology*
  • Pyloric Antrum / innervation
  • Pyloric Antrum / physiology*
  • Synapses / drug effects
  • Synaptic Transmission / drug effects


  • Clonidine
  • Acetylcholine
  • Norepinephrine