Badr K F, Mong S, Hoover R L, Schwartzberg M, Ebert J, Jacobson H R, Harris R C
Department of Medicine, Vanderbilt University, Nashville, Tennesee 37232.
Am J Physiol. 1989 Aug;257(2 Pt 2):F280-7. doi: 10.1152/ajprenal.1989.257.2.F280.
We examined the characteristics of [3H]leukotriene D4 (LTD4) binding to mesangial cells in culture. Binding is stereoselective, specific, saturable, and rapidly reversible. Two binding sites are recognized with dissociation constants and binding site densities at equilibrium of 2.2 and 16.8 nM and 1.1 x 10(4) and 3 x 10(4) binding sites per cell. LTD4, LTE4, (5R,6S)LTD4, LTB4, and the LTD4-receptor antagonist, SKF 104353, competitively inhibit radioligand binding in the following rank order of potency: LTD4 greater than LTE4 = SKF 104353 greater than (5R,6S)LTD4 greater than LTB4. LTD4 also induces time- and concentration-dependent phosphoinositide hydrolysis in mesangial cells. Formation of inositol 1,4,5-trisphosphate (IP3) is maximal at 5 s, followed by a time-dependent increase in inositol monophosphate generation, and inhibited by 100-fold excess concentration of SKF 104353. Addition of LTD4 to mesangial cells is associated with an increase in intracellular pH and dose-dependent stimulation of [3H]thymidine incorporation and mitogenesis. Thus rat mesangial cells possess specific binding sites for LTD4, the activation of which stimulates IP3 formation and induces cellular alkalinization and mitogenic responses. These studies provide insight into the cellular basis for LTD4-mesangial cell interactions, which are of potential pathophysiological relevance during acute glomerular inflammatory injury.
我们研究了培养的系膜细胞中[3H]白三烯D4（LTD4）结合的特性。结合具有立体选择性、特异性、饱和性且快速可逆。识别出两个结合位点，其解离常数和平衡时的结合位点密度分别为2.2和16.8 nM，以及每个细胞1.1×10(4)和3×10(4)个结合位点。LTD4、LTE4、(5R,6S)LTD4、LTB4以及LTD4受体拮抗剂SKF 104353按以下效力等级顺序竞争性抑制放射性配体结合：LTD4＞LTE4 = SKF 104353＞(5R,6S)LTD4＞LTB4。LTD4还可诱导系膜细胞中时间和浓度依赖性的磷酸肌醇水解。肌醇1,4,5-三磷酸（IP3）的形成在5秒时达到最大值，随后肌醇单磷酸生成随时间增加，并受到100倍过量浓度的SKF 104353的抑制。向系膜细胞中添加LTD4与细胞内pH值升高以及[3H]胸苷掺入和有丝分裂的剂量依赖性刺激相关。因此，大鼠系膜细胞具有LTD4的特异性结合位点，其激活可刺激IP3形成并诱导细胞碱化和有丝分裂反应。这些研究为LTD4与系膜细胞相互作用的细胞基础提供了见解，这在急性肾小球炎性损伤期间可能具有病理生理学相关性。
