LONDON – Several studies have shown that potentially fatal heart rhythm disturbances (ventricular arrhythmias) are more likely to occur in the morning upon waking.
The trigger mechanism is not yet fully understood, but a recent study conducted by researchers from Imperial College London revealed that these heart disorders are linked to the natural rise of the stress hormone, cortisol, which reaches its peak in our blood in the morning.
In the study conducted on mice, they found that cortisol binds to a specific receptor in heart cells. The receptor travels to the nucleus, where it affects genes that regulate ion channels in the cell membrane, which control the heartbeat.
As the activity of ion channels changes, the heart becomes more vulnerable because it is easier for the regular electrical impulses that cause a regular heartbeat to degrade into more chaotic activity, or arrhythmia.
The circadian, or nocturnal, cortisol rhythm is influenced by sleep, with an increase in cortisol just minutes before an individual wakes up.
The discovery of the link also raises the possibility of finding new treatments in this field.
Dr. Alicia D’Souza of the National Heart and Lung Institute (HNLI) and her colleagues sought to show that injecting a drug that blocks cortisol receptors into mice prevents morning changes in ion channels, and thus also prevents morning susceptibility to heart rhythm disturbances.
“Our hearts are literally different organs at different times of the day,” D’Souza said. They are most vulnerable in the early morning due to ancient circadian rhythms, which evolved over millions of years. “And all species have these in common, so although our study was conducted in mice, we believe this applies directly to human and mammalian hearts.”
Professor James Leeper, Associate Medical Director at the British Heart Foundation, explained: “Ventricular arrhythmia can occur at any time and, if left untreated, can lead to loss of consciousness, sudden cardiac arrest, and death. “It is important that we continue to investigate the causes of arrhythmias so that we can take action to prevent them.”
He continued: “This interesting study on mice reveals a potential solution to the mystery that makes ventricular arrhythmias more common in the morning. Identifying high cortisol as the culprit might allow us to explore new treatment options that might reduce arrhythmia in people most at risk. “More research will be necessary to determine whether these results also appear in humans.”
The study was published in the journal Circulation Research.
Source: Medical Express
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2024-04-05 22:42:06
