PHILADELPHIA — Omega-3 fatty acids found in oily fish may have diverse health-promoting effects, potentially protecting the immune, nervous, and cardiovascular systems.
But how the health effects of one such fatty acid -- docosahexaenoic acid (DHA) -- works remains unclear, in part because its molecular signaling pathways are only now being understood.
Toshinori Hoshi, PhD, professor of Physiology, at the Perelman School of Medicine, University of Pennsylvania, and colleagues showed, in two papers out this week in the Proceedings of the National Academy of Sciences, how fish oils help lower blood pressure via vasodilation at ion channels. In vascular smooth muscle cells, such as those that line blood vessels, ion channels that span the outer membrane of a cell to let such ions as sodium, calcium, and potassium in and out, are critical to maintaining proper vessel pressure.
The researchers found that DHA rapidly and reversibly activates these channels by increasing currents by up to 20 fold. DHA lowers blood pressure in anesthetized wild type mice but not in mice genetically engineered without a specific ion channel subunit.
In comparison, the team found that a dietary supplement, DHA ethyl ester, found in most fish oil pills fails to activate the same channels, and even antagonizes the positive effect of DHA from natural sources, on the cells. The DHA ethyl ester seems to compete with the natural form of DHA for binding sites on the ion channel.
The team concluded that these channels have receptors for long-chain omega-3 fatty acids, and that DHA -- unlike its ethyl ester cousin -- activate the channels and lower blood pressure.
The findings have practical implications for the use of omega-3 fatty acids as nutraceuticals for the general public and also for critically ill patients who may receive omega-3–enriched formulas as part of their nutrition.
Coauthor Michael Bauer from Jena University Hospital in Germany, who studies sepsis in a clinical setting, says the findings may encourage physicians to have a closer look at the specific formulations given to sepsis patients as they may contain either the free omega-3 acid or the ester.
The findings also underscore the importance of obtaining omega-3 fatty acids from natural food sources such as oily fish.
The study was supported, in part, by the National Institutes of Health (R01GM057654), the German Research Foundation, and Natural Science Foundation of China.
Penn Medicine is one of the world’s leading academic medical centers, dedicated to the related missions of medical education, biomedical research, excellence in patient care, and community service. The organization consists of the University of Pennsylvania Health System and Penn’s Raymond and Ruth Perelman School of Medicine, founded in 1765 as the nation’s first medical school.
The Perelman School of Medicine is consistently among the nation's top recipients of funding from the National Institutes of Health, with $550 million awarded in the 2022 fiscal year. Home to a proud history of “firsts” in medicine, Penn Medicine teams have pioneered discoveries and innovations that have shaped modern medicine, including recent breakthroughs such as CAR T cell therapy for cancer and the mRNA technology used in COVID-19 vaccines.
The University of Pennsylvania Health System’s patient care facilities stretch from the Susquehanna River in Pennsylvania to the New Jersey shore. These include the Hospital of the University of Pennsylvania, Penn Presbyterian Medical Center, Chester County Hospital, Lancaster General Health, Penn Medicine Princeton Health, and Pennsylvania Hospital—the nation’s first hospital, founded in 1751. Additional facilities and enterprises include Good Shepherd Penn Partners, Penn Medicine at Home, Lancaster Behavioral Health Hospital, and Princeton House Behavioral Health, among others.
Penn Medicine is an $11.1 billion enterprise powered by more than 49,000 talented faculty and staff.