Hypertension drug, L-type calcium channel blockers, may increase risk of heart failure, shows study
According to the World Health Organisation, 113 crore people worldwide have hypertension. When blood flows through the arteries (the major blood vessels), it puts pressure against the walls of the arteries. This pressure is called the blood pressure, but when this pressure gets too high, it is called hypertension (or high blood pressure).
Hypertension is one of the most serious medical conditions which is considered to increase the risk of heart disease, brain disease and various other diseases. There are different medications that are used for the treatment of hypertension such as the angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), diuretics, beta-blockers and calcium channel blockers. In a recent research published in the journal PNAS on 21 July, 2020, a research team led by Penn State found that L-type calcium channel blockers prescribed to many hypertension patients, may pose a threat to the heart.
On examining the epidemiological data from the Penn State clinical database, the researchers found that the incidents of heart failure were significantly higher in those patients of hypertension who were treated with L-type calcium channel blockers than in those who were on other hypertension medications.
How do L-type calcium channel blockers work in the body?
The walls of the blood vessels are made up of vascular smooth muscle cells (VSMCs), which help the vessels control the blood flow by compressing and relaxing. This activity of the blood vessels is regulated with the help of calcium. The VSMCs contain a number of calcium-permeable channels which control the calcium concentration.
When there is high blood pressure, these channels let too much calcium enter VSMCs, which triggers the cells to undergo some structural changes called remodelling. This makes the VSMCs divide and proliferate, thus making the blood vessel walls thick and stiff, leading to further increase in the blood pressure.
The L-type calcium channel blockers prevent the remodelling of the cells and also control the increased blood pressure.
How do these L-type calcium channel blockers backfire?
However, the scientists in their examination found that while preventing remodelling, the L-type calcium channel blockers simultaneously promoted the multiplication of VSMCs. The scientists from Penn state used optical, electrophysiological and molecular tools to examine VSMCs in the test tube and also in rats.
The team found that calcium enters into VSMCs with the help of stromal-interaction molecule (STIM) proteins which activate the ORAI calcium channels (present in the outer membrane of the cells). STIM is a protein that senses and coordinates the calcium signals inside a cell. This allows the extra calcium to get in through the ORAI calcium channels.
Also, continuous intake of L-type calcium channel blockers causes these STIM proteins to become overactive, which further triggers the VSMCs to multiply, thus thickening the blood vessels.
This increases the risk of heart failure in people who are being prescribed L-type calcium channel blockers for their hypertension.
For more information, read our article on High blood pressure.
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