Zhao Y D, Springall D R, Hamid Q, Yacoub M H, Levene M, Polak J M
Department of Histochemistry, Royal Postgraduate Medical School, London.
J Cardiovasc Pharmacol. 1995;26 Suppl 3:S336-40.
The localization and characterization of endothelin-1 (ET-1) binding in sections of transplanted and control human lung tissues was investigated by in vitro autoradiography. Binding of [25I]ET-1 was saturable and specific, and demonstrated a single class of binding sites. Scatchard analysis of the data revealed a Kd of 0.52 +/- 0.15 nM and a Bmax of 61.17 +/- 4.5 amol/mm2 to normal lung parenchyma, and a Kd of 0.48 +/- 0.29 nM and a Bmax of 123.9 +/- 18.5 amol/mm2 to normal bronchial smooth muscle. In transplanted human lung, the binding characterizations were similar to those of normal lung. Scatchard analysis indicated high-affinity sites having a Kd of 0.8 +/- 0.19 nM and a Bmax of 153.6 +/- 9.2 amol/mm2 to lung parenchyma and a Kd of 0.59 +/- 0.21 nM and a Bmax of 141.77 +/- 14.6 amol/mm2 to bronchial smooth muscle. Binding in transplanted and control tissues was similar and was inhibited by co-incubation with an excess of unlabeled ETs (ET-1 > ET-2 > ET-3) but not by other unlabeled peptides. Binding was mainly localized to lung parenchyma, small blood vessels [muscular pulmonary artery (100-500 mm) and bronchial blood vessels], pulmonary veins, and bronchial smooth muscle. The specific binding in small blood vessels was lower in transplanted lung than in control lung. Less specific binding was found in elastic pulmonary vessels than in small blood vessels in both transplanted and control lungs. No binding was found in the cellular perivascular infiltrates of the transplanted lung. These results suggest that ET-1 acts intrinsically and that high-affinity receptors for it exist in transplanted lung both in the parenchyma and bronchial smooth muscle.
通过体外放射自显影技术研究了内皮素 -1（ET-1）在移植的和对照的人肺组织切片中的结合定位及特性。[25I]ET-1 的结合具有饱和性和特异性，显示为单一类别的结合位点。对数据进行 Scatchard 分析表明，正常肺实质的解离常数（Kd）为 0.52±0.15 nM，最大结合容量（Bmax）为 61.17±4.5 amol/mm2；正常支气管平滑肌的 Kd 为 0.48±0.29 nM，Bmax 为 123.9±18.5 amol/mm2。在移植的人肺中，结合特性与正常肺相似。Scatchard 分析表明，肺实质的高亲和力位点的 Kd 为 0.8±0.19 nM，Bmax 为 153.6±9.2 amol/mm2；支气管平滑肌的 Kd 为 0.59±0.21 nM，Bmax 为 141.77±14.6 amol/mm2。移植组织和对照组织中的结合情况相似，与过量未标记的内皮素（ET-1＞ET-2＞ET-3）共同孵育可抑制结合，但其他未标记的肽则无此作用。结合主要定位于肺实质、小血管[肌性肺动脉（100 - 500μm）和支气管血管]、肺静脉和支气管平滑肌。移植肺中小血管的特异性结合低于对照肺。在移植肺和对照肺中，弹性肺血管中的特异性结合均少于小血管。在移植肺的血管周围细胞浸润中未发现结合。这些结果表明，ET-1 具有内在作用，并且在移植肺的实质和支气管平滑肌中均存在其高亲和力受体。
