Abstract: Objective To explore the mechanism of rapamycin -eluted stent in vascular endothelial injury. Meth⁃ ods （1）Rapamycin (rapamycin group) was injected to rabbit dorsum muscle to simulate rapamycin-eluted stent implanta⁃ tion into muscles. Control group and acetone control group were established at the same time. Morphological change in mus⁃ cle was observed and serum calcium levels were measured after rapamycin injection.（2）HUVECs were incubated with 0.1, 1, 10 and 100 μg/L rapamycin for 48 h respectively or with 1 μg/L rapamycin for 6, 12, 24 and 48 h respectively．Cell via⁃ bility was examined by MTT and its relationship with drug concentration and treatment time were analyzed.（3）HUVECs were divided into control group and 1 μg/L rapamycin group. After 48 h，morphological changes of HUVECs were assessed by HE staining，the production of nitric oxide was examined by Nitric Oxide Assay Kit and the intracellular calcium ion con⁃ centration was tagged with Fluo-3/AM. Results (1) Organizational morphology in local muscle with rapamycin injection represent stent implantation of rabbit，and calcium content in local muscle increased significantly in rapamycin group com⁃ pared with nomal control group and acetone control group（P < 0.05）. (2) Cell survival rate decreased significantly upon ad⁃ ministration of rapamycin in both concentration and time dependent manner（P < 0.01）. (3) In rapamycin group, cytoplasm vacuoles, nucleus pycnosis and nuclear fragmentation were observed；compared with control group，the levels of intracellular free Ca2+ increased while the levels of nitric oxide was reduced. Conclusion Rapamycin treatment lead of injury to vascular endothelial cells which might through up-regulating intracellular Ca2+ level.

Key words: Sirolimus, endothelium, vascular, drug-eluting stents, umbilical veins, calcium, disease models, animal