An examination of 5-hydroxytryptamine receptors in human saphenous vein.
We have examined the effects of antagonists on the isometric contraction of the human saphenous vein produced by 5-hydroxytryptamine (5-HT). The 5-HT2-antagonist ketanserin (1 microM) had little effect on the lower part of the concentration-response curve to 5-HT, but markedly shifted the upper part of the curve. Yohimbine caused an approximately parallel shift of the concentration-response curve to 5-HT, with a pA2 of 5.48, much lower than its pA2 against noradrenaline in the absence (6.36) or presence (7.06) of cocaine. It is concluded that there are two components to the contractile response to 5-HT in human saphenous vein: at low concentrations 5-HT activates a yohimbine-sensitive receptor, and at higher concentrations 5-HT activates a 5-HT2-receptor.
D000328:Adult; D000368:Aged; D003042:Cocaine / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; 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 / Q000187:drug effects; D012701:Serotonin / Q000494:pharmacology; D015016:Yohimbine / Q000494:pharmacology
D011985:Receptors, Serotonin; D015016:Yohimbine; D012701:Serotonin; D003042:Cocaine; D009638:Norepinephrine