Correlating endothelin releasing function of vascular endothelial cells to tea polyphenols and angiotensin Ⅱ / 中国组织工程研究

ABSTRACT

BACKGROUND: Angiotensin Ⅱ (Ang-Ⅱ) can stimulate vascular endothelial cells to excrete endothelin, a kind of potent vasoconstrictor. The content of endothelin in blood or cell culture media directly reflects the function and injured status of vascular endothelial cells. Therefore, it is significant for strengthening vascular endothelial cells to resist the injured factors. Tea polyphenols is a mainly active component of tea, and it is considered as a reagent for anti-atherosclerosis, protecting injuries of vascular endothelial cells and preventing cardiovascular diseases. OBJECTIVE: To observe the effects of tea polyphenols in different concentrations on endothelin content in vascular endothelial cells induced by Ang-Ⅱ at various time points through establishing Ang-Ⅱ-induced vascular endothelial cell injury models and further to investigate the protective effect of tea polyphenols on vascular endothelial cells. DESIGN: Observational study.SETTING: Aerospace and Diving Medical Center, Navy General Hospital of Chinese PLA.MATERIALS The experiment was carried out in Laboratory of Aerospace and Diving Medical Center, Navy General Hospital of Chinese PLA from March to September 2005. Main materials were detailed as follows Ang-Ⅱ (Sigma Company), tea polyphenols (Department of Tea Science, Zhejiang University) and vascular endothelial cells (human large artery vascular endothelial cell system, CBI Company, USA).METHODS: Cultured vascular endothelial cells were divided into 4 groups ① Control group The normal culture media was added in the isopyknic vascular endothelial cells, and 100 μL supernatant was extracted before and at 0.5, 6 and 24 hours after filling moisturized liquid. ② Ang-Ⅱ group Cell culture media containing 10-7 mol/L Ang-Ⅱ was added in the vascular endothelial cells, and other operations were as the same as those in the control group. ③ High-concentration tea polyphenols + Ang-Ⅱ group Cell culture media containing 50 mg/L tea polyphenols was added in the vascular endothelial cells, and other operations were as the same as those in the Ang-Ⅱ group. ④ Low-concentration tea polyphenols + Ang-Ⅱ group Cell culture media containing 25 mg/L tea polyphenols. 100 μL supernatant was extracted before and after 0.5, 6 and 24 hours treatment in each group. Thereafter, radioimmunoassay was used to measure the content of endothelin. MAIN OUTCOME MEASURES: Content of endothelin.RESULTS: ① Content of endothelin in Ang-Ⅱ group was higher than that in the control group (P ＜ 0.01). ② At 6 and 24 hours after high-concentration tea polyphenols incubation, content of endothelin in high-concentration tea polyphenols + Ang-Ⅱ group was lower than that in Ang-Ⅱ group (P ＜ 0.01). Moreover, the content of endothelin in low-concentration tea polyphenols + Ang-Ⅱ group was lower than that in both high-concentration tea polyphenols + Ang-Ⅱ group and angiotensin Ⅱ group (P ＜ 0.01). CONCLUSION: Tea polyphenols has inhibitory effects on endothelin releasing function of vascular endothelial cells induced by Ang-Ⅱ, suggesting that tea polyphenols has protective effect on vascular endothelial cells, and the effect of low-concentration tea polyphenols is superior to that of the high-concentration one.