Roubert P, Gillard V, Plas P, Guillon J M, Chabrier P E, Braquet P
Institut Henri Beaufour Les Ulis, France.
Biochem Biophys Res Commun. 1989 Oct 31;164(2):809-15. doi: 10.1016/0006-291x(89)91531-3.
[125I]ET-1 binding to vascular smooth muscle cells showed an apparent single class of high affinity recognition sites with a Kd of 2.12 +/- 0.46 nM and a Bmax of 81.2 +/- 5.2 fmol/10(6) cells. The specific binding was equally and totally displaced by ET-1 and ET-2 whereas ET-3 presented a different pattern. We investigated heterologous regulation of ET-1 binding sites by preincubating the cells with angiotensin II (AII), Arg-vasopressin, bradykinin, enkephalins, serotonin, norepinephrine and carbachol, for 18 h at 37 degrees C. Only AII pretreatment resulted in an important and dose-dependent decrease of ET-1 binding capacity. Sar1-Ile8-AII inhibited the regulatory effect of AII. Furthermore, preexposure of the cells with phorbol-12,13 dibutyrate but not with phorbol-12,13 didecanoate also resulted in a concentration-dependent diminution of ET-1 binding sites. These findings suggest that AII may selectively down-regulate ET-1 binding sites in vascular smooth muscle cells by a mechanism involving protein kinase C.
[125I]内皮素-1与血管平滑肌细胞的结合显示出一类明显的高亲和力识别位点，解离常数（Kd）为2.12±0.46纳摩尔，最大结合容量（Bmax）为81.2±5.2飞摩尔/10⁶个细胞。内皮素-1和内皮素-2能同等程度地完全取代特异性结合，而内皮素-3呈现出不同的模式。我们通过在37℃下将细胞与血管紧张素II（AII）、精氨酸加压素、缓激肽、脑啡肽、血清素、去甲肾上腺素和卡巴胆碱预孵育18小时，研究了内皮素-1结合位点的异源调节。只有AII预处理导致内皮素-1结合能力出现重要的剂量依赖性下降。Sar1-Ile8-AII抑制了AII的调节作用。此外，用佛波醇-12,13-二丁酸酯而非佛波醇-12,13-二十二酸酯预先处理细胞，也导致内皮素-1结合位点浓度依赖性减少。这些发现表明，AII可能通过涉及蛋白激酶C的机制选择性下调血管平滑肌细胞中的内皮素-1结合位点。
