豚鼠肺膜LTD_4受体结合特征及二苯乙烯低聚体(Gn-3)的LTD_4受体拮抗作用

Studies on the characteristics of LTD_4 receptor with radio-ligand binding assay and the effect of Gn-3

目的 采用LTD4 放射受体结合实验方法 ,在分析LTD4 受体的有关特征的基础上 ,观察比较二苯乙烯低聚体 (Gn 3)对LTD4 受体的拮抗作用。方法 以豚鼠肺膜为实验材料 ,采用3 H LTD4 为放射配体 ,以FPL55712 作阳性对照药物 ,Gn 3为实验药物 ,进行药物竞争结合实验。采用离体器官生物检测法鉴定Gn 3对LTD4 受体的拮抗作用。结果 3 H LTD4 与其相应受体呈现单一结合位点 ,其Kd 和Bmax值分别为 19.9× 10 -11mol·L-1和 2 32 .9fmol·mg-1蛋白。Gn 3可明显取代3 H LTD4 与其受体结合 ,IC50 值为 5 .71× 10 -7mol·L-1,Ki值为 2 .5 4× 10 -7mol·L-1。生物学鉴定法证实Gn 3可抑制LTD4 引起的生物学效应。结论 豚鼠肺膜LTD4 受体为单一结合位点受体 ,Gn 3为高活性的LTD4 受体拮抗剂。

OBJECTIVE To study the effect of Gn 3 on the LTD 4 receptor by using a radio ligand binding assay of LTD 4.METHODS Lung membrane of guinea pig was used as experimental materials, 3H LTD was used as radio ligand,FPL 55712 was chosen as the positive control drug,Gn 3 was used as the tested drug and bioassay in vitro was used to determine the biological function of Gn 3.RESULTS The binding of 3H LTD 4 to its receptor was specific,saturable and reversible.The K d and B max values were 19.9×10 -11 mol·L -1 and 232.9 fmol·mg -1 protein respectively at 30℃.Gn 3 inhibited 3H LTD 4 in competing against LTD 4 receptor.The IC 50 and K i value were 5.71×10 -7 mol·L -1 and 2.54×10 -7 mol·L -1 respectively.It was also determined that Gn 3 was LTD 4 receptor antagonist by the bioassay in vitro.CONCLUSION The binding of 3H LTD 4 on guinea pig lung membrane showed a single binding site.Gn 3 appeared to be an effective LTD 4 receptor antagonist.