Sung C P, Arleth A J, Shikano K, Berkowitz B A
Department of Pharmacology, Smith Kline and French Laboratories, Philadelphia, Pennsylvania.
J Pharmacol Exp Ther. 1988 Oct;247(1):8-13.
One of many important roles of the naturally occurring nonapeptide bradykinin (BK) is the modulation of vascular tone. As endothelial cells may play vital roles in the physiology of vascular tissues, it is important to understand the interaction of this peptide with endothelial cells. By using radiolabeled BK we have demonstrated for the first time BK specific binding sites in membranes of bovine pulmonary artery endothelial cells. There are two types of receptors shown in binding assay: one with a saturable, high-affinity binding (Kd = 1.28 +/- 0.21 nM, maximum binding = 111.4 +/- 12.0 fmol/mg) and the other with not readily saturable, low-affinity binding. The activation of BK receptors on bovine pulmonary artery endothelial cells is assessed by two functional assays, namely, the release of endothelium-derived relaxing factor and the elevation of cytosolic calcium. The characteristics of the BK receptors in both binding and functional assays indicate that the high-affinity binding is to B2 receptors and the low-affinity binding is to B1 receptors on the cells. Thus, high-affinity binding is blocked by B2 antagonists, D-Arg[Hyp3, thienylalanine5,8,D-Phe7]-BK and [thienylalanine5,8, D-Phe7]-BK and low-affinity binding is blocked by B1 antagonist des-Arg9[Leu8]-BK. The elevation of intracellular calcium and the release of endothelium-derived relaxing factor in response to BK in endothelial cells is predominately through B2 receptor activation. The ability to subtype BK receptors in endothelial cells may facilitate the understanding of the vascular functions of BK and the potential design of drugs to regulate these functions.
天然存在的九肽缓激肽（BK）的众多重要作用之一是调节血管张力。由于内皮细胞可能在血管组织的生理学中发挥至关重要的作用，因此了解这种肽与内皮细胞的相互作用很重要。通过使用放射性标记的BK，我们首次在牛肺动脉内皮细胞膜中证明了BK特异性结合位点。结合试验显示有两种类型的受体：一种具有可饱和的高亲和力结合（Kd = 1.28 +/- 0.21 nM，最大结合 = 111.4 +/- 12.0 fmol/mg），另一种具有不易饱和的低亲和力结合。通过两种功能试验评估牛肺动脉内皮细胞上BK受体的激活，即内皮源性舒张因子的释放和细胞溶质钙的升高。结合试验和功能试验中BK受体的特征表明，高亲和力结合是细胞上的B2受体，低亲和力结合是细胞上的B1受体。因此，高亲和力结合被B2拮抗剂D-Arg[Hyp3,噻吩丙氨酸5,8,D-苯丙氨酸7]-BK和[噻吩丙氨酸5,8,D-苯丙氨酸7]-BK阻断，低亲和力结合被B1拮抗剂去-Arg9[亮氨酸8]-BK阻断。内皮细胞中BK引起的细胞内钙升高和内皮源性舒张因子的释放主要是通过B2受体激活。在内皮细胞中对BK受体进行亚型分类的能力可能有助于理解BK的血管功能以及调节这些功能的潜在药物设计。
