title: Agonist potencies of tryptamine derivatives at pre- and postjunctional receptors in canine saphenous vein.
abstract: Strips form canine saphenous veins were incubated with (3H)-noradrenaline and mounted for superfusion. 5-Hydroxytryptamine (5-HT inhibited the release of tritium caused by sustained electrical stimulation (2 Hz, 150 mA, 0.1 msec) being about 10 times more potent than noradrenaline. 5-HT inhibited contractions induced by intermittent electrical stimulation at 2 Hz but increased the tone of the preparations in the absence of stimulation. Agonist potencies of tryptamine derivatives at prejunctional 5-HT receptors were determined by calculating those concentrations which would reduce the contractile effect of 2 Hz to that of 1 Hz, agonist potencies at postjunctional 5-HT receptors were determined by estimating the concentration which produces 50% of maximum response (pD2 values). Comparison of the agonist potencies at pre- and postjunctional receptors of various tryptamine derivatives suggest that in canine saphenous vein the two types of 5-HT receptor are structurally similar.
mesh_terms: D000818:Animals; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D011985:Receptors, Serotonin / Q000187:drug effects*; D012501:Saphenous Vein / Q000294:innervation*; D012701:Serotonin / Q000494:pharmacology; D013329:Structure-Activity Relationship; D014316:Tritium; D014363:Tryptamines / Q000494:pharmacology*
chemical_list: D011985:Receptors, Serotonin; D014363:Tryptamines; D014316:Tritium; D012701:Serotonin; D009638:Norepinephrine