Westcott J Y, Henson J, McMurtry I F, O'Brien R F
Webb-Waring Lung Institute, University of Colorado Health Sciences Center, Denver 80262.
Exp Lung Res. 1990 Sep-Oct;16(5):521-32. doi: 10.3109/01902149009068824.
The uptake and metabolism of endothelin was studied in the isolated perfused rat lung. 125I-Labeled endothelin (4 x 10(-12) M) was rapidly removed from the lung perfusate. More than 90% of the label was removed by 5 min, and only 4-5% remained in the perfusate after 30 min. In the presence of 10(-9) or 5 x 10(-9) M unlabeled endothelin added 6 min before 125I-labeled endothelin, the radiolabel was more slowly removed, so that after 30 min 19 or 73% of the label, respectively, remained in the perfusate. Although a high level of unlabeled endothelin in the perfusate reduced the uptake of 125I-labeled endothelin, it did not displace radiolabel previously taken up by the lung. Analysis of radiolabel composition showed that endothelin metabolism was less than 15% in both the lung and the perfusate after 30 min of lung perfusion. Autoradiography of the lung indicated that the radiolabel was located primarily within the alveolar wall. These results suggest that circulating endothelin is readily but finitely taken up in the pulmonary microvasculature where it is avidly bound but slowly metabolized.
在离体灌注的大鼠肺中研究了内皮素的摄取和代谢。125I标记的内皮素（4×10⁻¹² M）从肺灌注液中迅速清除。5分钟内超过90%的标记物被清除，30分钟后灌注液中仅残留4 - 5%。在125I标记的内皮素加入前6分钟加入10⁻⁹或5×10⁻⁹ M未标记的内皮素时，放射性标记物清除较慢，30分钟后分别有19%或73%的标记物残留于灌注液中。尽管灌注液中高水平的未标记内皮素降低了125I标记内皮素的摄取，但它并未取代肺先前摄取的放射性标记物。放射性标记物组成分析表明，肺灌注30分钟后，肺和灌注液中的内皮素代谢均小于15%。肺的放射自显影显示放射性标记物主要位于肺泡壁内。这些结果表明，循环中的内皮素在肺微血管中易于但有限地被摄取，在那里它被 avidly 结合但代谢缓慢。 （注：avidly 在这里可能是拼写有误，推测可能是avidly，意为“贪婪地、热切地”，但按要求未作修改）
