Hwang S B
Merck Sharp & Dohme Research Laboratories, Department of Biochemical Regulation, Rahway, NJ 07065-0900.
Eur J Pharmacol. 1991 Apr 17;196(2):169-75. doi: 10.1016/0014-2999(91)90424-o.
Rat peritoneal polymorphonuclear leukocytes (PMNs) showed a single class of high affinity binding sites for platelet-activating factor (PAF) with an equilibrium dissociation constant (KD) of 4.74 (+/- 2.59) nM. Each cell contained 2.79 (+/- 1.40) x 10(4) receptors. In the isolated membranes at pH 7.0 in 10 mM MgCl2, 10 mM Tris and 0.25% bovine serum albumin, the KD value was 0.61 (+/- 0.1) nM, which is roughly identical to the KD values reported previously for various membrane systems under identical ionic conditions. The receptors were highly specific for PAF. Several receptor antagonists that are reported to inhibit the binding of [3H]PAF and the PAF-induced function in platelets could fully displace the binding. The biologically inactive enantiomer (enantio-C16-PAF), a PAF analog, azido-PAF, and an indene derivative of the PAF receptor antagonist, L-651,142, had different potencies to inhibit [3H]PAF binding to rat and human PMN membranes. L-652,731, a tetrahydrofuran analog of the PAF receptor antagonist was about 10 times more potent to inhibit the binding in rat liver tissues than in rat PMNs. These results suggest that PAF receptors on human and rat PMNs are not identical and that PAF receptor subtypes may exist in rat liver and PMNs.
大鼠腹膜多形核白细胞（PMNs）显示出一类对血小板活化因子（PAF）具有高亲和力的结合位点，其平衡解离常数（KD）为4.74（±2.59）nM。每个细胞含有2.79（±1.40）×10⁴个受体。在10 mM MgCl₂、10 mM Tris和0.25%牛血清白蛋白存在下，pH 7.0的分离膜中，KD值为0.61（±0.1）nM，这与先前在相同离子条件下报道的各种膜系统的KD值大致相同。这些受体对PAF具有高度特异性。据报道，几种能抑制[³H]PAF结合及血小板中PAF诱导功能的受体拮抗剂可完全取代结合。生物活性无活性对映体（对映体-C16-PAF）、PAF类似物叠氮基-PAF以及PAF受体拮抗剂L-651,142的茚衍生物，在抑制[³H]PAF与大鼠和人PMN膜结合方面具有不同的效力。PAF受体拮抗剂的四氢呋喃类似物L-652,731在抑制大鼠肝组织中结合方面的效力比在大鼠PMN中约强10倍。这些结果表明，人和大鼠PMN上的PAF受体并不相同，并且PAF受体亚型可能存在于大鼠肝脏和PMN中。
