(Press-News.org)
New research explains how low levels of the electrolyte sodium in the blood can disrupt the timing of the heartbeat in patients taking widely used rhythm-control medications such as flecainide, which is commonly prescribed for atrial fibrillation and other fast or irregular heart rhythms.
The study, by Virginia Tech researchers at the Fralin Biomedical Research Institute in the journal Heart Rhythm, was conducted using guinea pig hearts and showed that blocking cardiac sodium channels with commonly prescribed medicine such as flecainide can make the heart’s electrical conduction unusually sensitive to even modest reductions in blood sodium levels.
Although sodium is often associated with dietary salt, when measured in medical settings it refers to the concentration of sodium ions in the blood — a factor for nerve and muscle function. When those levels drop below a critical level, a condition known as hyponatremia, electrical signaling in the heart can become unstable, especially in patients on sodium channel blockers.
“Doctors have long known that sodium channel blockers can slow cardiac conduction, and that low sodium levels are risky,” said Steven Poelzing, the study’s senior author and the James and Deborah Petrine Professor with the Fralin Biomedical Research Institute at VTC. “But what wasn’t clear is why the combination of the two is so problematic. This study helps explain the mechanism.”
The researchers found that when sodium channels are impaired, the heart relies more heavily on backup pathways to keep electrical signals moving. One of those pathways involves electrical interactions between neighboring heart cells in very narrow spaces — a process known as ephaptic coupling.
Another pathway involves the flow of potassium ions through channels that helps reset the heart’s electrical state. When sodium levels fall, these mechanisms don’t compensate as they normally would, causing conduction to slow more than expected.
“If you have the right amount of sodium in your blood, electrical activity will still move through the heart at the right speed — even when sodium channels are blocked,” Poelzing said. “But if you drop too low — because of vomiting, diarrhea, certain medications, or a medical condition — the drug may suddenly become detrimental.”
Importantly, the study shows that interfering with either ephaptic coupling or the net outward flow of potassium ions reduces the heart's sensitivity to low sodium when sodium channels are blocked. That insight opens the door to more targeted strategies for managing conduction risks in patients who rely on sodium channel blockers.
“This doesn’t mean every patient needs to worry but it is directly relevant to the clinical management of arrhythmias,” said Poelzing, who is with the Fralin Biomedical Research Institute’s Center for Vascular and Heart Research. “For some patients on drugs like flecainide, careful monitoring of sodium levels may be just as important as managing the arrhythmia itself.”
The findings also underscore the need for physicians to be aware of hidden interactions between drug therapy and electrolyte imbalances — particularly low sodium levels — especially in older adults or hospitalized patients, who may be more prone to hyponatremia.
“The study indicates that mean sodium levels shouldn’t be an afterthought — especially for those on heart rhythm medications,” Poelzing said. “A quick conversation with your doctor might help prevent a more serious problem down the line.”
Poelzing is also a professor of Biomedical Engineering and Mechanics in the Virginia Tech College of Engineering.
The study was led by Poelzing and William Adams, who was a student in the Translational Biology, Medicine, and Health graduate program working in Poelzing’s lab when the research took place. Research Assistant Professor Hoeker was among the co-authors. The research was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health.
END
CORVALLIS, Ore. – Following a large-scale wildfire, more jaguars migrated to a study site in the Brazilian wetlands that already had the largest population density of jaguars in the world, a new study found.
“Finding even more jaguars and other mammals in the study area following the 2020 wildfire and extreme drought suggests that it may serve as a climate refuge, buffering the effects of extreme climate events,” said Charlotte Eriksson, a post-doctoral scholar at Oregon State University.
The 36,700-acre site is a seasonally ...
Can you imagine a life-saving molecule whose “twin” is a deadly poison? As surprising as it may seem, this chemical reality is known as “chirality”. Like a right hand and a left hand, two molecules can have the same composition, but a different shape and arrangement in space. And this difference can change everything. Understanding and controlling this phenomenon is crucial to drug design. A team from the University of Geneva (UNIGE), in collaboration with the University of Pisa, has developed a new family of remarkably stable chiral molecules. This work opens up new prospects ...
A new paper in Environmental Toxicology and Chemistry, published by Oxford University Press, finds that efforts to eradicate invasive molluscs in Idaho’s Snake River may kill off valuable freshwater species.
Dreissenid mussels such as zebra and quagga mussels are invasive aquatic species that disrupt freshwater ecosystems and cause major economic and social damage. In the United States, observers first found Dreissenid mussels in the Great Lakes, likely introduced via international shipping vessels, in 1988. In subsequent decades Dreissenid mussels spread to lakes and rivers throughout the eastern and central United States, causing dramatic shifts in food chains, collapsed fisheries, ...
Every day, your body replaces billions of cells—and yet, your tissues stay perfectly organized. How is that possible?
A team of researchers at ChristianaCare’s Helen F. Graham Cancer Center & Research Institute and the University of Delaware believe they’ve found an answer. In a new study published today in the scientific journal Biology of the Cell, they show that just five basic rules may explain how the body maintains the complex structure of tissues like those in the colon, for example, even as its cells are constantly dying and being replaced.
This research is the product of more than 15 years of collaboration between mathematicians and cancer biologists ...
NIJMEGEN, The Netherlands, 15 July 2025 – In a comprehensive Genomic Press perspective (peer-reviewed review) article, an international team of neuroscientists has outlined crucial validity standards that could transform how researchers use stem cell technology to study devastating brain disorders. The framework addresses a critical gap in translating laboratory discoveries into effective treatments for neuropsychiatric conditions that affect billions globally.
Addressing the Translation Crisis
Neuropsychiatric ...
Stroke is said to be the second leading cause of death worldwide after heart disease. To prevent the death of neurons in the brain, a research group led by Osaka Metropolitan University Associate Professor Hidemitsu Nakajima of the Graduate School of Veterinary Science has developed a drug that inhibits a protein involved in cell death.
The multifunctional protein GAPDH (glyceraldehyde-3-phosphate dehydrogenase) is linked to pathogenesis in many intractable brain and nervous system diseases. The team developed GAI-17, a GAPDH aggregation inhibitor. When this inhibitor was administered to model ...
by Rachael Frost
Most people have heard of St John’s Wort and omega-3s. But did you know there are a lot more over-the-counter herbal products and supplements out there targeting depression? In our review of clinical trials of these products, we found 64 different over-the-counter (OTC) products that have been evaluated for depression – but with differing levels of evidence for each.
Why look at this topic?
Depression is increasingly common, to the extent that it is sometimes described as an ...
EMBARGOED UNTIL THURSDAY, JULY 15, 2025 AT 12:01 AM ET
Survey Finds Americans Choose Short Term Relief for Neck and Back Pain
Doctors say treatment should be individualized
ORLANDO, FL — New survey data from the Orlando Health Spine Center reveals a significant difference among Americans on how to manage neck and back pain. Respondents were split between relying on rest and reduced activity (44%), turning to over-the-counter pain relievers (42%), and hot/cold therapies (29%) — an uncertainty that may be discouraging some from seeking medical guidance.
“We ...
A cancer diagnosis is a life-changing event for patients that can cause short- and long-term mental health concerns as they shift to living within a new timeline driven by weeks or months between medical follow-up appointments. A new survey conducted on behalf of The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute (OSUCCC – James) highlights the widespread emotional impact of cancer, revealing what weighs heavy on the minds of adults when a loved one is diagnosed.
Kevin Johns, MD, director ...
Scientists from the Centenary Institute and the University of Sydney have made a landmark discovery that could lead to safer and more effective gene therapies for a range of serious genetic disorders including Duchenne muscular dystrophy, Pompe disease and haemophilia.
Published in the leading journal Cell, the study identifies a previously unknown gateway into human cells, a receptor called AAVR2, that gene therapy viruses use to deliver therapeutic genes. This newly uncovered pathway could allow lower ...