title: Evidence for two types of nicotinic receptors in the cat carotid body chemoreceptor cells.
abstract: Current concepts on the location and functional significance of nicotinic receptors in the carotid body rest on alpha-bungarotoxin binding and autoradiographic studies. Using an in vitro preparation of the cat carotid body whose catecholamine deposits have been labeled by prior incubation with the tritiated natural precursor [3H]tyrosine, we have found that nicotine induces release of [3H]catecholamines in a dose-dependent manner (IC50 = 9.81 microM). We also found that mecamylamine (50 microM) completely abolished the nicotine-induced release, while alpha-bungarotoxin (100 nM; approximately 20 times its binding Kd) only reduced the release by 56%. These findings indicate that chemoreceptor cells, and perhaps other carotid body structures, contain nicotinic receptors that are not sensitive to alpha-bungarotoxin and force a revision of the current concepts on cholinergic mechanisms in the carotid body chemoreception.
authors.affiliation: Departamento de Bioquímica y Biología Molecular y Fisiología, Facultad de Medicina, Universidad de Valladolid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Obeso
authors.forename: M A
authors.initials: MA
authors.lastname: Gómez-Niño
authors.forename: L
authors.initials: L
authors.lastname: Almaraz
authors.forename: B
authors.initials: B
authors.lastname: Dinger
authors.forename: S
authors.initials: S
authors.lastname: Fidone
authors.forename: C
authors.initials: C
authors.lastname: González
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D002038:Bungarotoxins / Q000378:metabolism; D002344:Carotid Body / Q000502:physiology*; D002395:Catecholamines / Q000378:metabolism*; D002396:Catechols / Q000378:metabolism; D002415:Cats; D002628:Chemoreceptor Cells / Q000502:physiology*; D066298:In Vitro Techniques; D007700:Kinetics; D008464:Mecamylamine / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009538:Nicotine / Q000494:pharmacology*; D011978:Receptors, Nicotinic / Q000145:classification / Q000187:drug effects / Q000502:physiology*; D014316:Tritium; D014443:Tyrosine / Q000378:metabolism
chemical_list: D002038:Bungarotoxins; D002395:Catecholamines; D002396:Catechols; D011978:Receptors, Nicotinic; D014316:Tritium; D015102:3,4-Dihydroxyphenylacetic Acid; D014443:Tyrosine; D008464:Mecamylamine; D009538:Nicotine; C034221:catechol