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.
ABSTRACT
Objective To observe changes of expression level of HSP70 protein in rat hippocampus after exposure to +Gz of different magnitudes and to investigate the machanism of HSP70 protein induced by +Gz exposure.Method One hundred rats were divided into: control group,+2 Gz group,+6 Gz group and +10 Gz group.The experimental rats were exposed to +2 Gz,+6 Gz and +10 Gz for 3 min respectively.The rats were killed 6 h,1 d,2 d,4 d,6 d after exposure and brain specimens were made for examination under microscope.The changes of HSP70 protein expression level were determined with immunohistochemical technology.Result The HSP70 protein expression level in the 3 experimental groups were significantly higher than that in control group.It began to rise 6 h after exposure,reached the peak after 1 d,and resumed to normal 6 d after exposure.The expression level was the highest in +6 Gz group and the lowest in +10 Gz group.Conclusion +Gz exposure can induce obvious changes of HSP70 protein expression level and the most prominent changes are found in rats after exposure to +6 Gz group.
ABSTRACT
Objective To determine the effect of heat and noise on erythrocyte memb rane ATPase activities in pilots during flying. Method Twenty- four pilots per forming bombing for 3h (45～53℃, 122～97dB in the cabin) served as the su bjects . 21 ground personnel served as control (27℃ in the room). Blood samples were t aken from both groups before flying (6:00 a.m), and immediately (12:00 a.m.) and 8h (8:00 p.m.) after flying. Na+-K+ATPase, and Ca2+-Mg2+ATPase activities in erythrocyte membran e were determined with colorimetry. Result The Na+-K+ATPase activity in eryth rocyte membrane at 6:00 a.m.in pilots was higher than that in control group at the s ame time (P<0.01). The Ca2+-Mg2+ATPase activities in erythrocyte membrane at 12:00 a .m. and 8:00 p.m. in pilots were significantly higher, compared with those in co ntrol group at the same time (P<0.01). Conclusion The ATPase values obtained in our study were all within normal range, and the daytim e variation of both groups are the same. Exposure of human body to heat and noi se for long time may be harmful, the higher ATPase activity is, the more catabol ism of ATP will be. ATP exhaustion will lead to Ca2+ overload in erythrocy te thus stiffen the red cell membrane.