Responses induced by acetylcholine and ATP in the rabbit petrosal ganglion.
Acetylcholine and ATP appear to mediate excitatory transmission between receptor (glomus) cells and the petrosal ganglion (PG) neuron terminals in the carotid body. In most species these putative transmitters are excitatory, while inhibitory effects had been reported in the rabbit. We studied the effects of the application of acetylcholine and ATP to the PG on the carotid nerve activity in vitro. Acetylcholine and ATP applied to the PG increased the carotid nerve activity in a dose-dependent manner. Acetylcholine-induced responses were mimicked by nicotine, antagonized by hexamethonium, and enhanced by atropine. Bethanechol had no effect on basal activity, but reduced acetylcholine-induced responses. Suramin antagonized ATP-induced responses, and AMP had little effect on the carotid nerve activity. Our results suggest that rabbit PG neurons projecting through the carotid nerve are endowed with nicotinic acetylcholine and purinergic P2 receptors that increase the carotid nerve activity, while simultaneous activation of muscarinic cholinergic receptors reduce the maximal response evoked by nicotinic cholinergic receptor activation.
Soto
Carolina R
CR
Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile. c_soto_r@yahoo.com
Ortiz
Fernando C
FC
Vargas
Romina V
RV
Arroyo
Jorge
J
Alcayaga
Julio
J
D000109:Acetylcholine / Q000494:pharmacology*; D000200:Action Potentials / Q000187:drug effects; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D018723:Bethanechol / Q000494:pharmacology; D002344:Carotid Body / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D004594:Electrophysiology; D005726:Ganglia, Parasympathetic / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D018738:Hexamethonium / Q000494:pharmacology; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009475:Neurons, Afferent / Q000187:drug effects; D009538:Nicotine / Q000494:pharmacology; D018722:Nicotinic Agonists / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D011817:Rabbits
D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D018722:Nicotinic Agonists; D018733:Nicotinic Antagonists; D018723:Bethanechol; D018738:Hexamethonium; D009538:Nicotine; D001285:Atropine; D000255:Adenosine Triphosphate; D000109:Acetylcholine