title: Purinergic and adrenergic transmission and their presynaptic modulation in canine isolated perfused splenic arteries.
abstract: Vasoconstrictions induced by periarterial electrical stimulation were analysed pharmacologically in the canine isolated perfused splenic artery. Phentolamine enhanced the vasoconstrictions at 1 Hz but inhibited those at 10 Hz. Suramin and P2x purinoceptor desensitization with alpha,beta-methylene ATP abolished the phentolamine-enhanced and -resistant vasoconstrictions. alpha,beta-Methylene ATP inhibited the vasoconstrictions at 1 Hz and by exogenous ATP but did not change those at 10 Hz and by exogenous noradrenaline. Suramin reduced the vasoconstrictions by the electrical stimulations and alpha,beta-methylene ATP but did not affect those by exogenous ATP. Prazosin did not affect the vasoconstrictions at 1 Hz but inhibited those at 10 Hz. Rauwolscine enhanced the prazosin-resistant vasoconstrictions. These results suggest that the electrical stimulation at 1 Hz releases purinergic transmitters (ATP or a closely related compound) as a dominant candidate for the vasoconstrictions, and a co-released noradrenaline may inhibit the release of purinergic transmitters through presynaptic alpha 2-adrenoceptors in the canine splenic artery.
authors.affiliation: Department of Pharmacology, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: L M
authors.initials: LM
authors.lastname: Ren
authors.forename: T
authors.initials: T
authors.lastname: Nakane
authors.forename: S
authors.initials: S
authors.lastname: Chiba
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005260:Female; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010477:Perfusion; D011224:Prazosin / Q000494:pharmacology*; D017729:Presynaptic Terminals / Q000187:drug effects*; D013157:Splenic Artery / Q000187:drug effects*
chemical_list: D000255:Adenosine Triphosphate; D009638:Norepinephrine; D011224:Prazosin