Different contributions of ATP and noradrenaline to neurotransmission in the isolated canine intermediate auricular artery.
Vasoconstrictor responses elicited by periarterial electrical nerve stimulation were analyzed pharmacologically in the canine isolated, perfused intermediate auricular artery. Phentolamine (10 microM) significantly inhibited the vasoconstrictor responses to stimulation at 5 Hz and over but not those to stimulation at frequencies below 5 Hz. Additionally administered alpha, beta-methylene ATP (1 microM) abolished the phentolamine-resistant vasoconstrictions at all frequencies used in this study. In contrast, suramin (100 microM) inhibited the vasoconstrictor responses to stimulation at 5 Hz and below but not those to stimulation at frequencies higher than 5 Hz. Phentolamine abolished the suramin-resistant vasoconstriction at all frequencies. Phentolamine and alpha, beta-methylene ATP selectively abolished the vasoconstrictor responses to exogenous noradrenaline and ATP, respectively. These results show that the co-transmission of noradrenaline and ATP exists at sympathetic nerve terminals in the canine intermediate auricular artery, and that purinergic transmission is mainly involved in the vasoconstrictor responses to low-frequency nerve stimulation.
Haniuda
K
K
Department of Pharmacology, School of Medicine, Shinshu University, Matsumoto, Japan.
Nakane
T
T
Chiba
S
S
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology*; D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000294:innervation*; D004285:Dogs; D004423:Ear / Q000098:blood supply* / Q000294:innervation; D004558:Electric Stimulation; D005260:Female; D006145:Guanethidine / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D010646:Phentolamine / Q000494:pharmacology; D058919:Purinergic P2 Receptor Antagonists; D013498:Suramin / Q000494:pharmacology; D013564:Sympathetic Nervous System / Q000187:drug effects; D013565:Sympatholytics / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects*; D013779:Tetrodotoxin / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D058919:Purinergic P2 Receptor Antagonists; D013565:Sympatholytics; D014662:Vasoconstrictor Agents; D013779:Tetrodotoxin; D013498:Suramin; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D009638:Norepinephrine; D010646:Phentolamine; D006145:Guanethidine