Ergul A, Glassberg M K, Wanner A, Puett D
Department of Biochemistry and Molecular Biology, University of Georgia, Athens 30602, USA.
Exp Lung Res. 1995 May-Jun;21(3):453-68. doi: 10.3109/01902149509023719.
Endothelin-1 (ET-1) has constrictor and mitogenic effects on airway smooth muscle strips and cultured cells, respectively. This study addresses the type of the ET receptor subtype(s) present on ovine airway smooth muscle cells and the possibility of autocrine effects. The expression of the preproendothelin-1 gene was demonstrated by Northern analysis, and the medium obtained from these cells contained immunoreactive-ET-1. Competitive binding experiments between [125I]ET-1 and ET-1, ET-3, and two ET-receptor subtype selective-ligands, BQ-123 (ETA) and sarafotoxin S6c (ETB), yielded IC50 values of 1.1 +/- 0.1, 227 +/- 13, 12 +/- 1, and 194 +/- 21 nM, respectively. ET-3 also gave a limited number of higher affinity sites. In the presence of BQ-123 (1 microM), the binding of [125I]ET-1 was decreased by 80-85%, and the IC50 values with ET-1, ET-3, and S6c were 2.0 +/- 0.4, 3.6 +/- 0.6, and 1.1 +/- 0.9 nM, respectively. In similar experiments with 0.1 microM sarafotoxin S6c, the respective IC50 values for ET-1 and ET-3 were 2.4 +/- 0.4 and 300 +/- 20 nM. These results demonstrate that about 85 +/- 5% of ET-1 binding to airway smooth muscle cells is to ETA receptors and that these cells produce ET-1 in vitro.
内皮素 -1（ET -1）对气道平滑肌条和培养细胞分别具有收缩和促有丝分裂作用。本研究探讨了绵羊气道平滑肌细胞上存在的ET受体亚型类型以及自分泌效应的可能性。通过Northern分析证实了前内皮素 -1基因的表达，并且从这些细胞获得的培养基中含有免疫反应性ET -1。[125I]ET -1与ET -1、ET -3以及两种ET受体亚型选择性配体BQ -123（ETA）和毒蜘蛛毒素S6c（ETB）之间的竞争性结合实验，得到的IC50值分别为1.1±0.1、227±13、12±1和194±21 nM。ET -3也给出了数量有限的高亲和力位点。在存在BQ -123（1μM）的情况下，[125I]ET -1的结合减少了80 - 85％，并且与ET -1、ET -3和S6c的IC50值分别为2.0±0.4、3.6±0.6和1.1±0.9 nM。在使用0.1μM毒蜘蛛毒素S6c的类似实验中，ET -1和ET -3的各自IC50值分别为2.4±0.4和300±20 nM。这些结果表明，与气道平滑肌细胞结合的ET -1中约85±5％是与ETA受体结合，并且这些细胞在体外产生ET -1。
