title: Modulatory effects of histamine on cat carotid body chemoreception.
abstract: Histamine has been proposed to be an excitatory transmitter between the carotid body (CB) chemoreceptor (glomus) cells and petrosal ganglion (PG) neurons. The histamine biosynthetic pathway, its storage and release, as well as the presence of histamine H1, H2 and H3 receptors have been found in the CB. However, there is only indirect evidence showing the presence of histamine in glomus cells, or weather its application produces chemosensory excitation. Thus, we studied the histamine immunocytochemical localization in the cat CB, and the effects of histamine, and H1, H2 and H3 receptor blockers on carotid sinus nerve (CSN) discharge, using CB and PG preparations in vitro. We found histamine immunoreactivity in dense-cored vesicles of glomus cells. Histamine induced dose-dependent increases in CSN discharge in the CB, but not in the PG. The H1-antagonist pyrilamine reduced the CB responses induced by histamine, the H2-antagonists cimetidine and ranitidine had no effect, while the H3-antagonist thioperamide enhanced histamine-induced responses. Present data suggests that histamine plays an excitatory modulatory role in the generation of cat CB chemosensory activity.
authors.affiliation: Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Del Rio
authors.forename: Esteban A
authors.initials: EA
authors.lastname: Moya
authors.forename: Cecilia S
authors.initials: CS
authors.lastname: Koenig
authors.forename: Kunio
authors.initials: K
authors.lastname: Fujiwara
authors.forename: Julio
authors.initials: J
authors.lastname: Alcayaga
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Iturriaga
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002344:Carotid Body / Q000166:cytology* / Q000378:metabolism*; D002415:Cats; D002628:Chemoreceptor Cells / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D004305:Dose-Response Relationship, Drug; D006632:Histamine / Q000378:metabolism* / Q000494:pharmacology; D017442:Histamine Agonists / Q000494:pharmacology; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D054828:Histamine H3 Antagonists / Q000494:pharmacology; D000860:Hypoxia / Q000503:physiopathology; D066298:In Vitro Techniques; D008297:Male; D016253:Microscopy, Immunoelectron / Q000379:methods; D009538:Nicotine / Q000494:pharmacology; D018722:Nicotinic Agonists / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011738:Pyrilamine / Q000494:pharmacology; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D017442:Histamine Agonists; D006634:Histamine H1 Antagonists; D054828:Histamine H3 Antagonists; D018722:Nicotinic Agonists; D010880:Piperidines; D009538:Nicotine; D006632:Histamine; D014446:Tyrosine 3-Monooxygenase; D011738:Pyrilamine; C052075:thioperamide; D000109:Acetylcholine