Regulating effect of tea polyphenols on endothelin, intracellular calcium concentration, and mitochondrial membrane potential in vascular endothelial cells injured by Angiotensin II.

BACKGROUND

Polyphenols are the main active component of tea and are considered an antiatherosclerosis agent, protecting vascular endothelial cells (VECs) from injury and preventing cardiovascular diseases. Endothelin level, intracellular calcium concentration, and mitochondrial membrane potential in VECs directly reflect the function and injury status of cells. The objective of this study was to study the regulating effects of tea polyphenols on these factors in VECs injured by angiotensin II (Ang-II) and explore the protective effect of tea polyphenols on human VECs.

METHODS

In this study, human aortic vascular endothelial cells were divided into 4 groups: (1) a control group; (2) Ang-II group: Ang-II at a concentration of 10(-7) mol/L was added to the cells; (3) low-concentration tea polyphenols + Ang-II group: tea polyphenols at a concentration of 5 mg/L was added in addition to Ang-II; (4) high-concentration tea polyphenols + Ang-II group: tea polyphenols at a concentration of 25 mg/L was added in addition to Ang-II. One hundred microliters of supernatant was extracted before treatment and at 0.5, 6, and 24 hours after treatment in each group to establish the content of endothelin.

RESULTS

The results showed the following: (1) tea polyphenols decreased the expression of endothelin-1 messenger RNA, which was increased by Ang-II (P < 0.01). (2) Tea polyphenols inhibited endothelin secretion induced by Ang-II (P < 0.01), and the inhibition of low-concentration tea polyphenols was superior to that of high concentration tea polyphenols (P < 0.01). (3) Tea polyphenols ameliorated the changes in intracellular calcium concentration and mitochondrial membrane potential induced by Ang-II (P < 0.01).

CONCLUSIONS

This study suggests that tea polyphenols may effectively protect VECs against injury by regulating endothelin, intracellular calcium concentration, and mitochondrial membrane potential in VECs injured by Ang-II. Additionally, lower dose would be used clinically rather than the higher dose for obtaining better results.