title: Chemosensitivity of unmyelinated axons in isolated human gastric vagus nerve.
abstract: Vagal afferent neurons from the stomach may be activated not only by chemical stimuli in the mucosa but also by circulating factors. In the present study, we have used electrophysiological techniques to characterize functional activity of several receptors for chemical mediators on unmyelinated axons in isolated fascicles of human gastric vagus nerve. Application of agonists at the nicotinic acetylcholine receptor (nAChR), 5-HT(3) subtype of serotonin receptor, and the transient receptor potential vanilloid receptor-1 (TRPV1) resulted in a change in the height and/or threshold of the C-fiber compound action potential. These effects were blocked by specific antagonists of nAChR (mecamylamine), 5-HT(3) (Y-25130), and TRPV1 (capsazepine). We conclude that the chemosensitivity of unmyelinated vagal axons can be studied using isolated segments of human gastric vagus nerve. The presence of receptors indicates that circulating factors may modify vagal afferent neurons also by effects on the axonal membrane.
authors.affiliation: Department of Anesthesiology, University of Munich, Germany. philip.lang@med.uni-muenchen.de
authors.forename: Philip M
authors.initials: PM
authors.lastname: Lang
authors.forename: Peter
authors.initials: P
authors.lastname: Grafe
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000368:Aged; D001369:Axons / Q000187:drug effects / Q000502:physiology; D002211:Capsaicin / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002628:Chemoreceptor Cells / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005753:Gastric Mucosa / Q000294:innervation* / Q000502:physiology*; D006801:Humans; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008875:Middle Aged; D036421:Nerve Fibers, Unmyelinated / Q000187:drug effects / Q000502:physiology*; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology*; D018722:Nicotinic Agonists / Q000494:pharmacology; D009620:Nodose Ganglion / Q000187:drug effects / Q000502:physiology; D009924:Organ Culture Techniques; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000502:physiology; D044406:Receptors, Serotonin, 5-HT3 / Q000187:drug effects / Q000502:physiology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D050916:TRPV Cation Channels / Q000187:drug effects / Q000502:physiology; D014630:Vagus Nerve / Q000187:drug effects / Q000502:physiology*; D017833:Visceral Afferents / Q000187:drug effects / Q000502:physiology*
chemical_list: D018722:Nicotinic Agonists; D011978:Receptors, Nicotinic; D044406:Receptors, Serotonin, 5-HT3; D017366:Serotonin Receptor Agonists; D050916:TRPV Cation Channels; C494482:TRPV1 protein, human; D002211:Capsaicin