Savi P, Laplace M C, Herbert J M
Sanofi Recherche, Hemobiology Research Department, Toulouse, France.
Thromb Res. 1994 Oct 15;76(2):157-69. doi: 10.1016/0049-3848(94)90186-4.
[3H]-2-Methylthio-ADP ([3H]-2-MeS-ADP), a stable analogue of ADP bound to one type of specific binding sites on rat platelets (KD = 0.77 +/- 0.07 nM, Bmax = 160 +/- 11 fmol/10(8) cells). 2-MeS-ADP and ADP antagonized [3H]-2-MeS-ADP binding, showing respective Ki values of 1.4 +/- 0.1 nM and 486 +/- 78 nM. Clopidogrel, a potent and specific inhibitor of ADP-induced platelet aggregation partially inhibited (approximately 70% inhibition) the binding of [3H]-2-MeS-ADP at the same time it abrogated 2-MeS-ADP- and ADP-induced adenylyl cyclase inhibition and aggregation. A population of clopidogrel-resistant [3H]-2-MeS-ADP binding sites was detected on platelets from treated animals. These receptor sites (KD = 0.9 +/- 0.2 nM, Bmax = 47 +/- 5 fmol/10(8) platelets) which showed high affinity for both ADP and 2-MeS-ADP (Ki values in the nanomolar range) might be involved in the ADP-induced shape change, a clopidogrel-resistant ADP-induced event. Using clopidogrel which acts via a direct and irreversible inhibition of ADP binding to its adenylyl cyclase-coupled receptor sites on platelets, we were able to discriminate between two types of ADP receptor sites. The former which was clopidogrel-sensitive represented about 70% of the total [3H]-2-MeS-ADP receptors and was responsible for ADP-induced platelet aggregation and adenylyl cyclase inhibition. The latter which was not affected by clopidogrel might be involved in ADP-induced shape-change.
[3H]-2-甲硫基-ADP（[3H]-2-MeS-ADP）是一种与大鼠血小板上一种特定结合位点结合的ADP稳定类似物（解离常数KD = 0.77±0.07 nM，最大结合容量Bmax = 160±11 fmol/10⁸个细胞）。2-MeS-ADP和ADP拮抗[3H]-2-MeS-ADP的结合，其各自的抑制常数Ki值分别为1.4±0.1 nM和486±78 nM。氯吡格雷是一种强效且特异性的ADP诱导血小板聚集抑制剂，在消除2-MeS-ADP和ADP诱导的腺苷酸环化酶抑制及聚集的同时，部分抑制（约70%抑制）[3H]-2-MeS-ADP的结合。在经处理动物的血小板上检测到一群对氯吡格雷耐药的[3H]-2-MeS-ADP结合位点。这些受体位点（KD = 0.9±0.2 nM，Bmax = 47±5 fmol/10⁸个血小板）对ADP和2-MeS-ADP均表现出高亲和力（Ki值在纳摩尔范围内），可能参与ADP诱导的形态变化，这是一种对氯吡格雷耐药的ADP诱导事件。利用通过直接且不可逆抑制ADP与其血小板上腺苷酸环化酶偶联受体位点结合而起作用的氯吡格雷，我们能够区分两种类型的ADP受体位点。前者对氯吡格雷敏感，约占总[3H]-2-MeS-ADP受体的70%，负责ADP诱导的血小板聚集和腺苷酸环化酶抑制。后者不受氯吡格雷影响，可能参与ADP诱导的形态变化。
