Tetrahydroisoquinolines and beta-carbolines: specific binding to human platelet alpha 2-receptors in vitro.
Previous human platelet aggregation studies indicated that tetrahydroisoquinoline (TIQ) and beta-carboline (BC) compounds act as competitive antagonists for epinephrine for the platelet alpha 2-adrenergic receptor. In this study, the relative binding affinities of 1,2,3,4-TIQ (THIQ), salsolinol (SAL), norharman (NH), harmaline (HAR) and tetrahydronorharman (THN) for the platelet alpha 2-receptor were determined using the selective antagonist [3H]-yohimbine. The order of potency in yohimbine-displacing ability was THIQ = THN greater than HAR greater than NH greater than SAL, with IC50's ranging from 10 microM to 170 microM. A structure-activity relationship could also be identified for the condensation products examined.
D001667:Binding, Competitive; D001792:Blood Platelets / Q000378:metabolism*; D002243:Carbolines / Q000097:blood*; D002462:Cell Membrane / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007211:Indoles / Q000097:blood*; D007546:Isoquinolines / Q000097:blood*; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D044005:Tetrahydroisoquinolines; D015016:Yohimbine / Q000097:blood
D002243:Carbolines; D007211:Indoles; D007546:Isoquinolines; D011942:Receptors, Adrenergic, alpha; D044005:Tetrahydroisoquinolines; D015016:Yohimbine; C014843:1,2,3,4-tetrahydroisoquinoline