[A preliminary study of immuno-electron microscopy of endothelium in cardiovascular system]

The immunocytochemical localizations of the von Willebrand factor (vWF), endothelin-1 (ET-1) and the beta 2-adrenergic receptor (beta 2R) in cultured human umbilical vein endothelial cells (HUVEC) after thrombin treatment have been demonstrated. Competitive ELISA analysis of these treated cells indicate an increase in vWF deposition on the subendothelial matrix (1.5 folds vs control) and vWF release (3.8 folds vs control) in the culture medium. The vWF-peroxidase, immunogold labeling and in situ hybridization of ET-1 were demonstrated on HUVEC. Double labelling with different sized gold particles for the ET-1 and beta 2R locations were performed on the hearts of young adult WEY, SHR, and SHRsp rats. The results were as follows. (1) Positive vWF deposits were detected on the extracellular matrix, Weibel-Palade bodies and secreting vesicles in the cytoplasm. It is suggested that both the constituted and regulated pathways are involved in the secretion of vWF stimulated by thrombin. (2) The gene expression of ET-1 was detected by light microscopic in situ hybridization in HUVEC. (3) ET-1 was detected by immunoelectron microscopy in the lysosome, cell surface, and extracellular matrix, suggesting that lysosome possibly plays an important role in the processing of ET-1 in HUVEC. (4) The presence of both ET-1 and beta 2R have been successfully detected in adult heart tissues and the endothelial cells of rats. These observations suggest the functional importance of ET-1 and beta 2R.