title: Release of [3H]noradrenaline induced by 5-hydroxytryptamine from cat pial arteries.
abstract: Pial arteries of cats were used to analyse the effects of 5-hydroxytryptamine (5-HT) on the release of [3H]noradrenaline. To achieve this the vessels were preincubated with [3H]noradrenaline and the effect of different concentrations of 5-HT (10(-6), 10(-5), 10(-4) M) on the release of tritium was studied. 5-HT elicited release of radioactivity in a dose-dependent manner. Removal of both superior cervical sympathetic ganglia 15 days before the experiment of pretreatment of the animals with reserpine (3 mg kg-1, total dose) produced a significant decrease in the outflow of tritium induced by 5-HT. In these arteries, the amount of radioactivity retained at the end of the experiment was much diminished. Cocaine (10(-6) M) caused a significant decrease in the tritium efflux induced by 5-HT (1"0(-5) M). These results show that 5-HT has an indirect adrenergic effect in the pial arteries of the cat only at high doses of 5-HT, and confirm that sympathetic innervation of these vessels mainly comes from the superior cervical ganglia.
mesh_terms: D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000294:innervation / Q000378:metabolism; D001285:Atropine / Q000494:pharmacology; D002415:Cats; D003714:Denervation; D005260:Female; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D010424:Pentobarbital / Q000494:pharmacology; D010841:Pia Mater / Q000098:blood supply*; D012110:Reserpine / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D012701:Serotonin; D001285:Atropine; D012110:Reserpine; D010424:Pentobarbital; D009638:Norepinephrine