title: ATP responses in the embryo chick ciliary ganglion cells.
abstract: The ATP responses in ciliary neurons acutely dissociated from chick ciliary ganglia were investigated using the nystatin perforated patch recording mode. ATP induced a transient inward current at a holding potential of -50 mV in a concentration-dependent manner. The half-maximum effective concentration of ATP was 8.2 microM and the Hill coefficient was 0.9. The current-voltage relationship of the ATP response revealed a strong inward rectification at potentials more positive than -30 mV and the reversal potential was near 0 mV. The relative potencies of purinoceptor agonists were in the order of ATP > 2-methylthio-ATP > ADP. Neither adenosine, AMP nor alpha, beta-methylene-ATP induced any response. The ATP-induced inward current was blocked by suramin, a selective P2 purinoceptor antagonist, in a concentration-dependent manner. The half-maximum inhibitory concentration was 4.5 microM. The cytosolic Ca2+ concentration was increased by ATP and suramin inhibited the increase in a concentration-dependent manner. These results suggest that ATP operates non-selective cation channels by acting on P2y purinoceptors and has a role in the excitation of ciliary neurons.
authors.affiliation: Department of Neurology, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Abe
authors.forename: M
authors.initials: M
authors.lastname: Sorimachi
authors.forename: Y
authors.initials: Y
authors.lastname: Itoyama
authors.forename: K
authors.initials: K
authors.lastname: Furukawa
authors.forename: N
authors.initials: N
authors.lastname: Akaike
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002642:Chick Embryo; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D005726:Ganglia, Parasympathetic / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D013498:Suramin / Q000494:pharmacology
chemical_list: D013498:Suramin; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D002118:Calcium