title: Effects of 5-hydroxytryptamine on neuroeffector junction in human pulmonary artery.
abstract: The effects of 5-hydroxytryptamine on release of norepinephrine and on contraction of smooth muscle in human pulmonary artery were studied. Helical strips were prepared from intra-parenchymal arteries removed 3-18 h after death. The strips were labeled with L-[7-3H]norepinephrine and mounted for superfusion and isometric tension recording. Electrical stimulation (10 V, 2 ms, 2 Hz) of the strips increased the release of total radioactivity; this release was blocked by tetrodotoxin. 5-Hydroxytryptamine (10(-5) M) exerted a cocaine-sensitive, indirect sympathomimetic effect on the overflow of norepinephrine from resting strips. This action was not blocked by methysergide. No effect of 5-hydroxytryptamine on release of norepinephrine from electrically stimulated tissue could be demonstrated. 5-Hydroxytryptamine (10(-5) M) also caused contractions of pulmonary smooth muscle, not blocked by phentolamine (10(-5) M) but mediated in part through methysergide-sensitive 5-hydroxytryptamine receptors.
mesh_terms: D000293:Adolescent; D000328:Adult; D004558:Electric Stimulation; D006801:Humans; D008784:Methysergide / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009451:Neuroeffector Junction / Q000187:drug effects*; D009638:Norepinephrine / Q000378:metabolism; D011651:Pulmonary Artery / Q000187:drug effects* / Q000378:metabolism; D012701:Serotonin / Q000494:pharmacology*; D014316:Tritium
chemical_list: D014316:Tritium; D012701:Serotonin; D009638:Norepinephrine; D008784:Methysergide