Pu-Erh Tea Relaxes the Thoracic Aorta of Rats by Reducing Intracellular Calcium
Luo Dan, Chen Xuejiao, Zhu Xu, Liu Shuang, Li Jie, Xu Jianping, Zhao Jinhua, Ji Xu · Frontiers in Pharmacology · 2019 November 28
DOI 10.3389/fphar.2019.01430
Objective
In this work, the direct effects of pu-erh tea on vessels and cells were investigated by detecting isometric tension and intracellular calcium ([Ca2+]i), respectively.
Conclusions
In conclusion, theabrownins and caffeine should be the two main active components in pu-erh tea. Pu-erh aqueous extract vasodilated arteries in an endothelium-independent manner, which might partly be attributed to the decrease in extracellular Ca2+ influx. Moreover, our study provided data on the potential mechanism of the hypotensive actions of pu-erh tea, which might improve our understanding of the effect of pu-erh tea on the prevention and treatment of hypertension.
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Insights
Pu-erh tea's ability to lower blood pressure is primarily due to theabrownins and caffeine, which cause vasodilation irrespective of the endothelium.
For the research methodology, researchers used pu-erh tea aqueous extract to analyze its effects on rat thoracic aortas previously tightened by Phenylephrine or KCl. They observed the isometric tension and intracellular calcium to gauge the direct effects of the tea. The aqueous tea extract was separated into different fractions using organic solvents to identify the specific active components. They assessed the impact these had on the arteries.
The results demonstrated that the vessels relaxed in response to the pu-erh tea extract, irrespective of whether the endothelium was removed or preincubated with potassium channel blockers. Furthermore, the contractibility of the vessels induced by Phenylephrine or CaCl under different conditions was reduced. There was also a decrease in the KCl-induced increase of intracellular calcium in rat aortic smooth muscle cells. Among the different components, researchers found that the chloroform precipitate of the pu-erh tea extract resulted in the strongest vasodilation. Theabrownins, a major part of this precipitate, and caffeine were identified as the active components causing vasodilation in an endothelium-independent manner.
