title: Differences between sodium-dependent and desipramine-defined [3H]imipramine binding in intact human platelets.
abstract: Measurements of sodium-dependent [3H]imipramine binding to intact human platelets from 20 human volunteers were made and compared to desipramine-defined binding, a method commonly employed in population studies of platelet [3H]imipramine sites. The density (Bmax) of sodium-dependent [3H]imipramine sides in platelets was significantly lower (449 +/- 36 sites/platelet) and the affinity (Kd) significantly higher (1.15 +/- 0.12 nM) than those obtained when excess desipramine was used to define specific binding (Bmax 654 +/- 33 sites/platelet, p less than 0.001; Kd 1.52 +/- 0.11 nM, p less than 0.001). There was no significant correlation between the density (Bmax) of sodium-dependent and desipramine-defined binding in individual subjects, suggesting that a different proportion of sites are labeled under the two assay conditions. No age-dependent variation was found in either Kd or Bmax values of sodium-dependent or desipramine-defined [3H]imipramine binding. The results suggest determination of sodium-dependent [3H]imipramine binding to intact platelets may be a useful measure for the estimation of [3H]imipramine recognition sites relevant to the serotonin uptake in studies of patients with affective disorders.
authors.affiliation: Department of Pharmacology, School of Medicine, University of Ottawa, Canada.
authors.forename: P D
authors.initials: PD
authors.lastname: Hrdina
mesh_terms: D000328:Adult; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D002352:Carrier Proteins; D003891:Desipramine / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007099:Imipramine / Q000493:pharmacokinetics*; D008297:Male; D008875:Middle Aged; D011955:Receptors, Drug; D017981:Receptors, Neurotransmitter / Q000187:drug effects* / Q000378:metabolism; D012964:Sodium / Q000097:blood*
chemical_list: D002352:Carrier Proteins; D011955:Receptors, Drug; D017981:Receptors, Neurotransmitter; C027775:imipramine receptor; D012964:Sodium; D007099:Imipramine; D003891:Desipramine