title: Binding of [3H]imipramine to human platelet membranes with compensation for saturable binding to filters and its implication for binding studies with brain membranes.
abstract: Apparent specific binding of [3H]imipramine to human platelet membranes at high concentrations of imipramine showed deviation from that expected of a single binding site, a result consistent with a low-affinity binding site. The deviation was due to displaceable, saturable binding to the glass fibre filters used in the assays. Imipramine, chloripramine, desipramine, and fluoxetine inhibited binding to filters whereas 5-hydroxytryptamine and ethanol were ineffective. Experimental conditions were developed that eliminated filter binding, allowing assay of high- and low-affinity binding to membranes. Failure to correct for filter binding may lead to overestimation of binding parameters, Bmax and KD for high-affinity binding to membranes, and may also be misinterpreted as indicating a low-affinity binding component in both platelet and brain membranes. Low-affinity binding (KD less than 2 microM) of imipramine to human platelet membranes was demonstrated and its significance discussed.
mesh_terms: D001667:Binding, Competitive; D001792:Blood Platelets / Q000378:metabolism*; D002352:Carrier Proteins; D002462:Cell Membrane / Q000378:metabolism; D006801:Humans; D007099:Imipramine / Q000097:blood*; D007700:Kinetics; D011955:Receptors, Drug; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D014316:Tritium
chemical_list: D002352:Carrier Proteins; D011955:Receptors, Drug; D017981:Receptors, Neurotransmitter; C027775:imipramine receptor; D014316:Tritium; D007099:Imipramine