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有效的血管收缩肽。我们的免疫电镜显示，在er -高尔基系统中合成和分离的ET-1储存在webel - palade （WP）体中，并且由于大ET-1的免疫定位优先在限制膜上发现，而ET-1的免疫定位在WP体的中心，因此大ET-1到ET-1的加工部分发生在WP体中。这意味着从高尔基复合体中分离出来并储存在WP体中的大ET-1向ET-1的转化可能部分发生在WP体的极限膜上。目前，双免疫标记技术的进一步研究正在进行中。大鼠硬脑膜横窦内皮细胞WP小体对ET-1有免疫反应。内皮下平滑肌细胞的肌膜和小泡也有免疫反应。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小体还是大鼠颈动脉体动脉衍生的血管舒张肽CGRP的储存位点。利用免疫电镜双免疫标记技术，两种肽的免疫标记在同一WP小体的单个切片中优先共定位。颈动脉体具有独特的动脉微循环系统，这可能与化学感受器功能的效率有关。内皮细胞WP小体中同时存在血管收缩肽和血管扩张肽，提示这些肽在颈动脉小体局部血流调节中发挥重要作用。

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.