Storage and Release of Endothelin in Vascular Endothelial Cells

内皮素-1（ET-1）是由血管内皮细胞产生的一种强缩血管肽。我们的免疫电镜显示，ET-1，合成和分离的rER-高尔基体，是储存在韦伯-帕拉德（WP）机构和大ET-1的加工ET-1发生在WP机构的一部分，因为大ET-1的免疫定位优先发现的限制膜和ET-1的是在WP机构的中心。这说明从高尔基复合体中分离出来并贮存在WP体中的大ET-1向ET-1的转化可能部分发生在WP体的界膜上。应用免疫双标记技术进行了进一步的研究，结果表明，大鼠硬脑膜横窦内皮细胞WP小体对ET-1呈免疫反应性。在内皮下平滑肌细胞的肌膜和肌膜小窝中也观察到免疫反应。这表明ET-1在颅内静脉循环中的血流动力学作用，除了ET-1外，WP小体也是大鼠颈动脉体中血管舒张肽CGRP的储存部位。通过使用双重免疫标记技术的免疫电子显微镜，两种肽的免疫标记优先共定位在单个切片中的相同WP体中。颈动脉体具有独特的动脉微循环系统，可能与化学感受器功能的效率有关。血管收缩肽和血管舒张肽在内皮细胞WP体中的存在表明这些肽在颈动脉体中的血流的局部调节中起重要作用。

Endothelin-1 (ET-1) is a potent vasoconstrictive peptide produced by vascular endothelial cells. Our immunoelectron microscopy reveals that ET-1, synthesized and segregated in the rER-Golgi system, is stored in Weibel-Palade (WP) bodies and that the processing of big ET-1 to ET-1 occurs in part in WP bodies since immunolocalizations of big ET-1 is preferentially found on the limiting membrane and those of ET-1 is in the center of WP bodies. This means that the conversion of big ET-1 segregated from the Golgi complex and stored in WP bodies to ET-1 may in part occur at the limiting membrane of WP bodies. Further studies using the double immunolabeling technique are now in progress.WP bodies of endothelial cells of the transverse sinus of the rat dura mater are immunoreactive for ET-1. The immunoreactivities are also observed in the sarcolemma and caveoles of smooth muscle cells under the endothelium. This indicates hemodynamic roles of ET-1 in the intracranial venous circulation.In addition to ET-1, WP bodies are a storage site of CGRP,a vasodilatative peptide in the rat carotid body artery derived. By the immunoelectron microscopy using the double immunolabeling technique, immunolabelings of both peptides are preferentially colocalized in the same WP bodies in a single section. The carotid body possesses the peculiar arterial microcirculatory system which may be related to efficiencies of chemoreceptor function. The existence of both vasoconstrictive and vasodilative peptides in WP bodies of the endothelial cells suggests that these peptides play important roles in local regulation of the blood flow in the carotid body.