title: Inhibitory presynaptic 5-hydroxytryptamine (5-HT) receptors on the sympathetic nerves of the human saphenous vein.
abstract: Superfused strips of the human saphenous vein preincubated with 3H-noradrenaline were used to investigate the influences of serotonin (5-HT) receptor agonists and antagonists on the electrically evoked tritium overflow. 5-HT and the preferential 5-HT1A receptor agonist 8-OH-DPAT [8-hydroxy-2-(di-n-propylamino)tetralin] concentration-dependently inhibited the evoked 3H overflow. The evoked 3H overflow was not affected by 0.1 or 1 mumol/l TVX Q 7821 (2-(4-[4-(2-pyrimidinyl)-1-piperazinyl]-butyl)-1,2-benzoisothiazol -3(2H)one-1,1-dioxide), which selectively binds to 5-HT1A sites; TVX Q 7821 10 mumol/l produced an increase in overflow. The inhibitory effect of 5-HT on the impulse-evoked 3H overflow was abolished by the nonselective 5-HT receptor antagonist metitepin, but was not attenuated by propranolol. Metitepin also abolished the inhibitory effect of 8-OH-DPAT on evoked 3H overflow, whereas the 5-HT2 receptor antagonist ketanserin was inactive in this respect. There was also no antagonism of the effect of 8-OH-DPAT by the alpha 2-adrenoceptor antagonist rauwolscine or the dopamine receptor antagonist flupenthixol. These results suggest that both 5-HT and 8-OH-DPAT inhibit noradrenaline release by activating inhibitory 5-HT receptors on the sympathetic nerves of the human saphenous vein. These receptors possess similarities to 5-HT1 recognition sites, but a further subclassification is not yet possible on the basis of the available data.
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000328:Adult; D000368:Aged; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology; D011985:Receptors, Serotonin / Q000502:physiology*; D012501:Saphenous Vein / Q000294:innervation*; D012701:Serotonin / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology; D013564:Sympathetic Nervous System / Q000378:metabolism; D013764:Tetrahydronaphthalenes / Q000494:pharmacology
chemical_list: D011743:Pyrimidines; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D013764:Tetrahydronaphthalenes; D012701:Serotonin; C043077:ipsapirone; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D009638:Norepinephrine