DeMet E M, Chicz-DeMet A
Department of Psychiatry and Human Behavior, University of California, Irvine 92717.
Psychiatry Res. 1990 Dec;34(3):293-302. doi: 10.1016/0165-1781(90)90007-r.
The possible presence of multiple high affinity 3H-imipramine (3H-IMI) binding sites on blood platelets was studied using trypsin digestion and cyanoimipramine (CNIMI), a pseudo-irreversible inhibitor of 3H-IMI binding and serotonin uptake. Increasing concentrations of CNIMI resulted in a discontinuous curve with a plateau at intermediate concentrations (0.05-0.35 nM). CNIMI sensitive (0.25 nM) sites accounted for approximately half of total high affinity 3H-IMI binding as defined by displacement with 100 microM desipramine. Similar results were obtained when platelet membranes were pretreated with trypsin (0.21-0.84 mg/ml), and no additional inhibition was evident with a combination of both treatments. The present results suggest that 3H-IMI may bind to two separate types of high affinity sites. One subclass is apparently proteinaceous and sensitive to low concentrations of CNIMI, whereas the other is apparently nonproteinaceous and is CNIMI resistant.
利用胰蛋白酶消化法以及氰米帕明（CNIMI），一种3H-丙咪嗪（3H-IMI）结合和血清素摄取的拟不可逆抑制剂，研究了血小板上可能存在的多个高亲和力3H-IMI结合位点。CNIMI浓度的增加导致了一条不连续的曲线，在中间浓度（0.05 - 0.35 nM）处出现平台期。如用100 microM去甲丙咪嗪置换所定义的，对CNIMI敏感（0.25 nM）的位点约占总高亲和力3H-IMI结合的一半。当用胰蛋白酶（0.21 - 0.84 mg/ml）预处理血小板膜时，得到了相似的结果，并且两种处理联合使用时没有明显的额外抑制作用。目前的结果表明，3H-IMI可能与两种不同类型的高亲和力位点结合。一个亚类显然是蛋白质性质的，对低浓度的CNIMI敏感，而另一个显然是非蛋白质性质的，对CNIMI有抗性。
