The effect of atropine on the activation of 5-hydroxytryptamine3 channels in rat nodose ganglion neurons

Neuroscience. 1994 Oct;62(4):1287-92. doi: 10.1016/0306-4522(94)90360-3.


It has been suggested that changes in brain 5-hydroxytryptamine3 receptor function may contribute to some behavior disorders, such as anxiety, schizophrenia and drug abuse. We are using the whole-cell version of the patch-clamp technique to study the function of 5-hydroxytryptamine3 channels in neurons freshly dissociated from rat nodose ganglion. In these cells, 5-hydroxytryptamine elicits an inward current over the concentration range of 0.25-100 microM (EC50 = 2.62 microM) by activating 5-hydroxytryptamine3 receptors. The muscarinic cholinergic antagonist atropine reduced the amplitude of 5-hydroxytryptamine activated inward current in a concentration-dependent manner. Other muscarinic antagonists, scopolamine, dexetimide, the M1 muscarinic receptor antagonist pirenzepine, the M2 receptor antagonist methoctramine and the M3 receptor antagonist 4-DAMP methiodide also inhibited 5-hydroxytryptamine-induced inward current. Atropine did not appear to change the reversal potential of this current. In the presence of 5 microM atropine, the concentration-response curve for 5-hydroxytryptamine current was shifted to the right in a parallel fashion. The EC50 value for 5-hydroxytryptamine was increased from 2.62 to 8.76 microM. Schild plots of increasing atropine and 5-hydroxytryptamine concentrations revealed a pA2 value of 5.74 for atropine (apparent KD = 1.8 microM). These observations suggest that atropine competitively antagonizes the activation of a receptor for the neurotransmitter serotonin, a novel action of muscarinic antagonists in the nervous system. This effect of atropine may contribute to the clinical symptoms seen in severe atropine intoxication.

MeSH terms

  • Animals
  • Atropine / pharmacology*
  • Electric Conductivity
  • Ion Channels / drug effects*
  • Ion Channels / metabolism
  • Male
  • Muscarinic Antagonists / pharmacology
  • Neurons / metabolism*
  • Neurons / physiology
  • Nodose Ganglion / cytology
  • Nodose Ganglion / metabolism*
  • Nodose Ganglion / physiology
  • Osmolar Concentration
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Cell Surface / physiology
  • Serotonin / metabolism*


  • Ion Channels
  • Muscarinic Antagonists
  • Receptors, Cell Surface
  • Serotonin
  • Atropine