[ScienceDaily] New discovery explains green and black tea’s blood pressure lowering properties

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(Research results may lead to new antihypertensive drugs)

A new study from the University of California, Irvine shows that compounds in both green and black tea dilate blood vessels by activating ion channel proteins in the blood vessel walls. This discovery helps to explain the antihypertensive properties of tea and may lead to the design of new antihypertensive drugs.

Published in the Journal of Cellular Physiology and Biochemistry, the finding was made by the lab of Geoffrey Abbott, PhD, professor in the Department of Physiology and Biophysics at UCI School of Medicine. Kaitlyn Redford, a doctoral student at Abbott Lab, is the first author of the study titled “Activation of the KCNQ5 potassium channel underlies tea-induced vasodilation.”

Results from the study show that two catechin-type flavonoid compounds (epicatechin gallate and epigallocatechin-3-gallate) found in tea, each activate a specific ion channel protein called KCNQ5, which allows potassium ions diffuse out of the cell to reduce cell excitability. Since KCNQ5 is found in the smooth muscle that forms blood vessels, the activation of catechins in tea is also predicted to dilate blood vessels – a prediction confirmed by collaborators at the University of Copenhagen.

“We discovered using computer modeling and mutagenesis studies that specific catechins bind to the pin of the voltage sensor, which is part of KCNQ5 that allows the channel to open in response to with cellular stimulation. This association allows the channel to open much more easily and earlier in cell stimulation,” explains Abbott.

Because up to a third of the world’s adult population has hypertension, and the condition is considered the number one modifiable risk factor for global cardiovascular disease and premature death, New treatments for hypertension have great potential to improve global public health. Previous studies have demonstrated that consuming green or black tea can lower blood pressure by a small but consistent amount, and catechins have previously been found to contribute to this property. The identification of KCNQ5 as a novel target for the antihypertensive properties of tea catechins may facilitate the optimization of pharmacokinetics to improve potency or efficacy.

In addition to its role in controlling vascular tone, KCNQ5 is expressed in different parts of the brain, where it regulates electrical activity and signaling between neurons. Pathogenic KCNQ5 gene variants exist that impair its channel function and thus cause epileptic encephalopathy, a developmental disorder that is severely debilitating and causes frequent seizures. As catechins are able to cross the blood-brain barrier, the discovery of their ability to activate KCNQ5 may suggest a future mechanism for repairing damaged KCNQ5 channels to ameliorate disturbances of cerebral excitability due to dysregulation of the brain. their dysfunction.

Tea has been produced and consumed for more than 4,000 years, and more than 2 billion cups of tea are now consumed every day worldwide, second only to water in terms of the amount consumed by people globally. The three commonly consumed caffeinated teas (green, oolong and black) are all produced from the leaves of the evergreen species Camellia sinensis, the difference arising from different degrees of fermentation during tea production. .

Black tea is often mixed with milk before drinking in countries including the United Kingdom and the United States. The researchers in this study found that when black tea was applied directly to the cells containing the KCNQ5 channel, the addition of milk blocked the beneficial KCNQ5 activation effects of the tea. However, according to Abbott, “We do not believe this means that one needs to avoid milk when drinking tea to take advantage of the beneficial properties of tea. We believe that the environment in the human stomach that separates catechins from proteins and other molecules in milk may block the beneficial effects of catechins. “

This hypothesis was supported by other studies showing that the blood pressure-lowering benefits of tea were independent of milk intake. The team also found that, using mass spectrometry, heating green tea to 35 degrees Celsius changes its chemical composition in a way that makes it more effective in activating KCNQ5.

“Whether drinking iced tea or hot tea, this temperature is reached after drinking tea, because the human body temperature is about 37 degrees Celsius,” Abbott explains. “So simply by drinking the tea, we activate its beneficial, blood-pressure-lowering properties.”

This study was supported in part by the National Institutes of Health, the National Institute of General Health Sciences, the National Institute of Neurological Disorders and Stroke, the Lundbeck Foundation, and the Danmarks Frie Forskningsfond.

References:

  1. Kaitlyn E. Redford, Salomé Rogrant, Thomas A. Jepps, Geoffrey W. Abbott. KCNQ5 Potassium Channel Activation Underlies Vasodilation by Tea. Cellular Physiology and Biochemistry, 2021 DOI: 10.33594/000000337

Source: Science Daily

Link: https://www.sciencedaily.com/releases/2021/03/210308131703.htm

Author: Ngoc Khanh.

The article is translated and edited by ykhoa.org – please do not reup without permission!

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